Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Thursday 18 June 2015 19:32:34 MC Cason wrote:
> Gene,
>
>I just did a teardown of my HF 12x36, and replaced the spindle
> bearings.  What I found sickening, was that there was NO oiler hole
> for the rear bearing, and the front bearing's oiler hole was drilled
> to the wrong side of the bearing, and was mostly covered by the
> bearing cup.

Why am I not surprised.  Note: statement, not question. :)

In my 7x12, there is not a single provision to lube the spindle bearings.  
The bottom of the head casting is wide open with no intended way to lube 
the bearings at all. So I bought a new head, will remove the backgears 
completely, and make up a floor inside the casting so that I can fill it 
up enough with vactra that the remaining gears will throw a bit of it 
around, hopefully getting some into the bearings.  Drive will then be 
direct from the motor, to about a 6" wheel taperlocked to the back of 
the shaft where the change gear driver gear is now.

Everytime I have decided to rebuild some part of it better, I am blown 
away by just how crappy the 7x12 design was in 1975 when it first 
shipped stateside, but more amazed, that despite its shortcomings 
becoming world wide known, not a single thing has been done to address 
the real problem, a crappy design.  No fine tuning, nothing.

>I uploaded pictures to Flickr if anybody is interested.
> https://www.flickr.com/photos/46689581@N03/18128737943/in/album-721576
>52150681293/
>
> On 06/13/2015 08:38 PM, Gene Heskett wrote:
> >> I would not trust the Grizzly spindle bearings @ 6000 rpm unless I
> >> had removed, checked fit, regreased and set the bearing preload.
> >
> > And TBT, these are horrible, 15 minutes no load at 1600 revs raised
> > the quill temp 25F on my IR thermometer.  I am repeating the breakin
> > procedure, but I doubt if it will do much good, I believe them to be
> > seriously preloaded way too high.
> >
> > IMO, decent bearings are a must, but you do not get those in a $850
> > machine. So no complaints to Grizzly unless I can't find decent
> > bearings a year down the log.

Cheers, Gene Heskett
-- 
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[andy pugh]

On 19 June 2015 at 00:32, MC Cason  wrote:
>  I just did a teardown of my HF 12x36, and replaced the spindle
> bearings.  What I found sickening, was that there was NO oiler hole for
> the rear bearing, and the front bearing's oiler hole was drilled to the
> wrong side of the bearing,

My 9x20 lathe had oil holes drilled just far enough to insert the
oilers, but not all the way through to the bearings.

That's why I now always buy old machines made in the UK.

-- 
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[MC Cason]

Gene,

   I just did a teardown of my HF 12x36, and replaced the spindle 
bearings.  What I found sickening, was that there was NO oiler hole for 
the rear bearing, and the front bearing's oiler hole was drilled to the 
wrong side of the bearing, and was mostly covered by the bearing cup.

   I uploaded pictures to Flickr if anybody is interested.
https://www.flickr.com/photos/46689581@N03/18128737943/in/album-72157652150681293/


On 06/13/2015 08:38 PM, Gene Heskett wrote:
>> I would not trust the Grizzly spindle bearings @ 6000 rpm unless I had
>> removed, checked fit, regreased and set the bearing preload.
> And TBT, these are horrible, 15 minutes no load at 1600 revs raised the
> quill temp 25F on my IR thermometer.  I am repeating the breakin
> procedure, but I doubt if it will do much good, I believe them to be
> seriously preloaded way too high.
>
> IMO, decent bearings are a must, but you do not get those in a $850
> machine. So no complaints to Grizzly unless I can't find decent bearings
> a year down the log.
>
>

-- 
MC Cason
Eagle3D - Created by Matthias Weißer
github.com/mcason/Eagle3D



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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[andy pugh]

On 15 June 2015 at 17:44, Gene Heskett  wrote:
>> It is possible to bore a taper on a CNC milling machine but you need a
>> boring and facing head.
>
> Why? Is it not possible to write a G2 or G3 that in addition to spiraling
> down, tapers as it spirals?

You need a facing head to bore the hole. But there is absolutely no
reason that you can't circularly-interpolate a tapered hole.
You could even use a tapered milling cutter if you wanted a better finish.


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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Monday 15 June 2015 12:44:08 Gene Heskett wrote:
> On Monday 15 June 2015 06:35:17 andy pugh wrote:
> > On 15 June 2015 at 03:05, Gene Heskett  wrote:
> > > There is not room on the spindle for a taperlock,
> >
> > My servo motors have a tapped hole in the end of the spindle, and I
> > used this to make my own taperlock.
> > I bored out the pulley with a tapered bore (on my lathe, which might
> > be a bit of a catch-22 for you) and then made a thin sleeve with a
> > matching taper that was split and then fitted to the motor spindle/
> > A bolt then pulls the pulley down on to the taper, squeezing it down
> > onto the servo shaft and locking the pulley to it. It has worked
> > well so far.
>
> Hum, this might be possible.  If the insert was pushed against the
> plastic sleeve that holds the nut tension against the end bearing, and
> the split was wide enough to make room for the 5x5x10mm key, and the
> adjusting nut was used to push it onto the sleeve, a fit could be
> achieved that might work. If the taper was similar to the steep part
> of an R8 collet, it shouldn't be too hard to knock loose, steeper
> taper IOW than the 7 degrees of a taperlock.  How steep should it be
> in order to be more or less self releasing when the nut is loosened? 
> I know, look it up in #27. :)  Steel sleeve, 100 

Damn ancent fingers, that s/b 10mm
> thick hub at the bore 
> location, its 1/2" thick now.  There are finer grooved belts than the
> motor pulley has, but since the pulley is also the cooling fan, I'd
> druther not change, meaning I'll have to make a rim thats wider to use
> the existing poly belt, which IIRC is 9 of the more or less std groove
> size, or about an inch wide. If I put the 10mm that sits on the
> sleeve/shaft, dead center to the pulley face, there shouldn't be
> enough sideways force to waller it out if it does work loose.  I am
> thinking of a sheet of 1/8" screwed to the end of the head, bigger
> than the pulley, from which I can set some pillars, the ends of which
> will then be where the encoders mount will be.  The OD of the pillars
> would then support a swarf shield of sorts.  I like it.
>
> If I can find some slot interrupters that mount from the side, I
> should be able to make a disk, a bit smaller that the pulley rim with
> the slots in the ID.
>
> You are always the source of a way to do it even when I am burned out,
> thanks Andy.
>
> You were the source of the Wohlhaupter idea that I have used twice
> now, to extend a too short screw into the machining that should have
> been done to the screw were it long enough and extend it into the end
> thrust bearing and motor coupling in one case, on the lathe, the
> anchoring bearing for X is the front of the slider, but the motor is
> off the back of the screw.  Swarf shielding however has been a problem
> as its too easy to drive it past 0.00 and crush the shielding. On the
> lathe the limit/home switch is about .05mm from the end of outward
> travel, so if the switch doesn't trip, neither is it crushed. Biggest
> problem has been remembering to clean off the swarf on top of the
> carraige before hitting ctrl+home.
>
> > It is possible to bore a taper on a CNC milling machine but you need
> > a boring and facing head.
>
> Why? Is it not possible to write a G2 or G3 that in addition to
> spiraling down, tapers as it spirals?  Maybe with the canned
> threading, I know I have cut pipe tapered threads that way several
> times.  Just checking, I wrapped a G33 in quite a bit of math on the
> lathe, and I don't see why I could change the bit to scrape a smooth
> taper and run it at .002 tpmm. Cobble job, but should work. Drive as
> an outside taper to 27.95mm od at small end of cut,  then bore to
> 28.00mm should crack/part it off.  On the lathe, but could be done on
> the mill if it had an encoder. The GO704 WILL have one.  So will the
> little mill, if I ever get the damned pulleys made to make it a belt
> drive. :(  This one idea has started a chain of events it may take me
> a year to get it all done. I hope I have that year.  The medics are
> screwing around with a pulled muscle or something thats pissing me off
> with the amount of time being killed just to do a damned MRI. I've
> been laid up in excruciating pain for 3 weeks last Saturday & the MRI
> isn't scheduled till the 23rd.  Thats bull shit, enough of which will
> grow 200 bu/acre.  :(
>
> > http://www.cnczone.com/forums/vertical-mill-lathe-project-log/109301
> >-c nc-post1357394.html#post1357394
>
> Cheers, Gene Heskett

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Monday 15 June 2015 06:35:17 andy pugh wrote:
> On 15 June 2015 at 03:05, Gene Heskett  wrote:
> > There is not room on the spindle for a taperlock,
>
> My servo motors have a tapped hole in the end of the spindle, and I
> used this to make my own taperlock.
> I bored out the pulley with a tapered bore (on my lathe, which might
> be a bit of a catch-22 for you) and then made a thin sleeve with a
> matching taper that was split and then fitted to the motor spindle/ A
> bolt then pulls the pulley down on to the taper, squeezing it down
> onto the servo shaft and locking the pulley to it. It has worked well
> so far.
Hum, this might be possible.  If the insert was pushed against the 
plastic sleeve that holds the nut tension against the end bearing, and 
the split was wide enough to make room for the 5x5x10mm key, and the 
adjusting nut was used to push it onto the sleeve, a fit could be 
achieved that might work. If the taper was similar to the steep part of 
an R8 collet, it shouldn't be too hard to knock loose, steeper taper IOW 
than the 7 degrees of a taperlock.  How steep should it be in order to 
be more or less self releasing when the nut is loosened?  I know, look 
it up in #27. :)  Steel sleeve, 100 thick hub at the bore location, its 
1/2" thick now.  There are finer grooved belts than the motor pulley 
has, but since the pulley is also the cooling fan, I'd druther not 
change, meaning I'll have to make a rim thats wider to use the existing 
poly belt, which IIRC is 9 of the more or less std groove size, or about 
an inch wide. If I put the 10mm that sits on the sleeve/shaft, dead 
center to the pulley face, there shouldn't be enough sideways force to 
waller it out if it does work loose.  I am thinking of a sheet of 1/8" 
screwed to the end of the head, bigger than the pulley, from which I can 
set some pillars, the ends of which will then be where the encoders 
mount will be.  The OD of the pillars would then support a swarf shield 
of sorts.  I like it.

If I can find some slot interrupters that mount from the side, I should 
be able to make a disk, a bit smaller that the pulley rim with the slots 
in the ID.

You are always the source of a way to do it even when I am burned out, 
thanks Andy.

You were the source of the Wohlhaupter idea that I have used twice now, 
to extend a too short screw into the machining that should have been 
done to the screw were it long enough and extend it into the end thrust 
bearing and motor coupling in one case, on the lathe, the anchoring 
bearing for X is the front of the slider, but the motor is off the back 
of the screw.  Swarf shielding however has been a problem as its too 
easy to drive it past 0.00 and crush the shielding. On the lathe the 
limit/home switch is about .05mm from the end of outward travel, so if 
the switch doesn't trip, neither is it crushed. Biggest problem has been 
remembering to clean off the swarf on top of the carraige before hitting 
ctrl+home.

> It is possible to bore a taper on a CNC milling machine but you need a
> boring and facing head.

Why? Is it not possible to write a G2 or G3 that in addition to spiraling 
down, tapers as it spirals?  Maybe with the canned threading, I know I 
have cut pipe tapered threads that way several times.  Just checking, I 
wrapped a G33 in quite a bit of math on the lathe, and I don't see why I 
could change the bit to scrape a smooth taper and run it at .002 tpmm.  
Cobble job, but should work. Drive as an outside taper to 27.95mm od at 
small end of cut,  then bore to 28.00mm should crack/part it off.  On 
the lathe, but could be done on the mill if it had an encoder. The GO704 
WILL have one.  So will the little mill, if I ever get the damned 
pulleys made to make it a belt drive. :(  This one idea has started a 
chain of events it may take me a year to get it all done. I hope I have 
that year.  The medics are screwing around with a pulled muscle or 
something thats pissing me off with the amount of time being killed just 
to do a damned MRI. I've been laid up in excruciating pain for 3 weeks 
last Saturday & the MRI isn't scheduled till the 23rd.  Thats bull shit, 
enough of which will grow 200 bu/acre.  :(

> http://www.cnczone.com/forums/vertical-mill-lathe-project-log/109301-c
>nc-post1357394.html#post1357394

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[andy pugh]

On 15 June 2015 at 03:05, Gene Heskett  wrote:
> There is not room on the spindle for a taperlock,

My servo motors have a tapped hole in the end of the spindle, and I
used this to make my own taperlock.
I bored out the pulley with a tapered bore (on my lathe, which might
be a bit of a catch-22 for you) and then made a thin sleeve with a
matching taper that was split and then fitted to the motor spindle/ A
bolt then pulls the pulley down on to the taper, squeezing it down
onto the servo shaft and locking the pulley to it. It has worked well
so far.

It is possible to bore a taper on a CNC milling machine but you need a
boring and facing head.
http://www.cnczone.com/forums/vertical-mill-lathe-project-log/109301-cnc-post1357394.html#post1357394

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Sunday 14 June 2015 21:03:40 Dave Cole wrote:
> Squirrel cage motors driven by VFDs slip.  The motors have to slip to
> magnetize the rotor. If you want tight control of a Squirrel cage
> motor (as tight as possible) they put a encoder on the motor then run
> the motor in vector control mode, where the slip is compensated for by
> the drive. But there is still slip.  The motor doesn't operate in a
> synchronous way.
>
> There are of course motors designed to be controlled by VFDs and more
> particularly Vector VFDs with Encoders mounted on the tail end of the
> motor.   The motors have better insulation and are designed so they
> can be run with high torque at low speeds.
>
> Marathon Black Max motors are a good example of a motor designed for
> VFD vector control that can have an attached encoder.
>
> Warning:  Not cheap!

When you are buying cutting edge, expect to pay for the time spent 
sharpening the tech. :-)

> http://www.automationdirect.com/adc/Shopping/Catalog/Motors/AC_Motors_
>-_General_Purpose_and_Inverter_Duty_%280.25_-_300HP%29/AC_Motors_-_Inve
>rter_Duty,_Marathon_%280.25_-_100HP%29/Marathon_Black_Max_w-z-_Encoder_
>%280.25HP_to_30HP%29
>
> But they still don't operate in a synchronous mode.The only way to
> get synchronous operation (to my knowledge)  is to have a wound rotor
> or a permanent magnet rotor but then those motors aren't typically
> designed for inexpensive VFDs.
>
> >>That in either event does not seem to be a viable way to spin a
> >> 1/2-13
>
> USS tap at say 300 rpms. <<
>
> I believe that most rigid tapping setups with LinuxCNC are done with
> VFD driven spindle motors with some type of encoder attached.

Gee, I broke the mold, doing it with a treadmill motor.  My problem in 
doing it reliably is in this case, the basic fault of a poor, made out 
of plastic, drive train.  The motor can do it, but not w/o demolishing 
the plastic drive train parts.

So once I get the screws working ok in the GO704, next is making a 
sturdier drive for the lathe.  But once I get up to about 5 inches and 
beyond for the spindle drive pulley, they turn into auto parts with huge 
offsets between the pulley face and the shaft they turn, 2" or more in 
may cases.  So, since my lathe isn't big enough to pull a cutting tool 
at 3" radius w/o breaking or burning up plastic parts, I expect I'll 
have to cut those circles out of 1/2" alu plate, on the new mill.

There is not room on the spindle for a taperlock, so it will have to be 
bored to 28mm on the mill.  And a hand fitted 5x5mmx10mm keyway cut in 
the hub.  S/B fun.  Then I can drive that spindle direct with its own 
serpentine belt.  No breakable stepdowns along the way.  But because the 
28mm bearing surface is only 10mm wide, its got to be precisely done.  
Or trim things a bit to make room for the pulley between the adjusting 
lock nuts.  There is not a lot of room for that in the present 
configuration.  Sigh.  Compromise and every one made weakens it.

> Dave
>
> On 6/14/2015 8:17 PM, Gene Heskett wrote:
> > On Sunday 14 June 2015 17:32:07 andy pugh wrote:
> >> On 14 June 2015 at 17:14, Gene Heskett  wrote:
> >>> So how do we discern the induction motor,totally unsuitable for
> >>> vfd drive except near is design rpms, from the synchronous motor
> >>> at home on a vfd drive?
> >>
> >> I think there is a false assumption here. VFDs are _intended_ for
> >> driving induction motors. All my machines have squirrel-cage
> >> induction motors driven by VFDs on the spindles. The Harrison still
> >> has the original motor from 1970.
> >
> > Humm, that does not grok with what I understand is the actual motive
> > force that turns the induction motor armature.
> >
> > 1.  The slip angle that causes the current in the armatiure is
> > basically a velocity effect.  Reduce the driving frequency from 60
> > hz to 6hz, and one or both of 2 things are going to happen.
> >
> > 1a: The currents, because the inductance is still the same, now have
> > time to rise to destructive, fusing of the wire in the windings
> > levels.  This will likely saturate the iron at the same time.
> >
> > 1b: If the currents are controlled so that they remain the same,
> > then the rate of change of the magnetic field is reduced to 10%,
> > inducing only 10% of the currents in the squirrel caged armature,
> > with resulting severe loss of torque.  Not to 10%, but because the
> > effects are additive, but closer to 1% of the torque it can deliver
> > when drven at 60 HZ.
> >
> > That in either event does not seem to be a viable way to spin a
> > 1/2-13 USS tap at say 300 rpms.
> >
> > 2.  So, do I not understand what I have learned from 65 or 70 years
> > ago, or has a new way to drive such an induction motor that cancels
> > or defeats the low speed power/torque losses?
> >
> > Educate me please.
> >
> > Thanks.
> >
> > Cheers, Gene Heskett
>
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[John Figie]

Gene,

I don't think the torque falls that quickly with a V/Hz VFD.  There are
some curves in the pdf below.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/drives-wp002_-en-p.pdf&ved=0CC8QFjAFahUKEwjo7qHsxJDGAhUGWJIKHWywAFw&usg=AFQjCNH-R_jdyKKXf2kP8LYReeJPgc7Bzw&sig2=MvtG-z3sDNpwecVh7-oxhg

John Figie
Squirrel cage motors driven by VFDs slip.  The motors have to slip to
magnetize the rotor. If you want tight control of a Squirrel cage
motor (as tight as possible) they put a encoder on the motor then run
the motor in vector control mode, where the slip is compensated for by
the drive. But there is still slip.  The motor doesn't operate in a
synchronous way.

There are of course motors designed to be controlled by VFDs and more
particularly Vector VFDs with Encoders mounted on the tail end of the
motor.   The motors have better insulation and are designed so they can
be run with high torque at low speeds.

Marathon Black Max motors are a good example of a motor designed for VFD
vector control that can have an attached encoder.

Warning:  Not cheap!

http://www.automationdirect.com/adc/Shopping/Catalog/Motors/AC_Motors_-_General_Purpose_and_Inverter_Duty_%280.25_-_300HP%29/AC_Motors_-_Inverter_Duty,_Marathon_%280.25_-_100HP%29/Marathon_Black_Max_w-z-_Encoder_%280.25HP_to_30HP%29

But they still don't operate in a synchronous mode.The only way to
get synchronous operation (to my knowledge)  is to have a wound rotor or
a permanent magnet rotor but then those motors aren't typically designed
for inexpensive VFDs.

>>That in either event does not seem to be a viable way to spin a 1/2-13
USS tap at say 300 rpms. <<

I believe that most rigid tapping setups with LinuxCNC are done with VFD
driven spindle motors with some type of encoder attached.

Dave



On 6/14/2015 8:17 PM, Gene Heskett wrote:
> On Sunday 14 June 2015 17:32:07 andy pugh wrote:
>> On 14 June 2015 at 17:14, Gene Heskett  wrote:
>>> So how do we discern the induction motor,totally unsuitable for vfd
>>> drive except near is design rpms, from the synchronous motor at home
>>> on a vfd drive?
>> I think there is a false assumption here. VFDs are _intended_ for
>> driving induction motors. All my machines have squirrel-cage induction
>> motors driven by VFDs on the spindles. The Harrison still has the
>> original motor from 1970.
> Humm, that does not grok with what I understand is the actual motive
> force that turns the induction motor armature.
>
> 1.  The slip angle that causes the current in the armatiure is basically
> a velocity effect.  Reduce the driving frequency from 60 hz to 6hz, and
> one or both of 2 things are going to happen.
>
> 1a: The currents, because the inductance is still the same, now have time
> to rise to destructive, fusing of the wire in the windings levels.  This
> will likely saturate the iron at the same time.
>
> 1b: If the currents are controlled so that they remain the same, then the
> rate of change of the magnetic field is reduced to 10%, inducing only
> 10% of the currents in the squirrel caged armature, with resulting
> severe loss of torque.  Not to 10%, but because the effects are
> additive, but closer to 1% of the torque it can deliver when drven at 60
> HZ.
>
> That in either event does not seem to be a viable way to spin a 1/2-13
> USS tap at say 300 rpms.
>
> 2.  So, do I not understand what I have learned from 65 or 70 years ago,
> or has a new way to drive such an induction motor that cancels or
> defeats the low speed power/torque losses?
>
> Educate me please.
>
> Thanks.
>
> Cheers, Gene Heskett

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Dave Cole]

Squirrel cage motors driven by VFDs slip.  The motors have to slip to 
magnetize the rotor. If you want tight control of a Squirrel cage 
motor (as tight as possible) they put a encoder on the motor then run 
the motor in vector control mode, where the slip is compensated for by 
the drive. But there is still slip.  The motor doesn't operate in a 
synchronous way.

There are of course motors designed to be controlled by VFDs and more 
particularly Vector VFDs with Encoders mounted on the tail end of the 
motor.   The motors have better insulation and are designed so they can 
be run with high torque at low speeds.

Marathon Black Max motors are a good example of a motor designed for VFD 
vector control that can have an attached encoder.

Warning:  Not cheap!

http://www.automationdirect.com/adc/Shopping/Catalog/Motors/AC_Motors_-_General_Purpose_and_Inverter_Duty_%280.25_-_300HP%29/AC_Motors_-_Inverter_Duty,_Marathon_%280.25_-_100HP%29/Marathon_Black_Max_w-z-_Encoder_%280.25HP_to_30HP%29

But they still don't operate in a synchronous mode.The only way to 
get synchronous operation (to my knowledge)  is to have a wound rotor or 
a permanent magnet rotor but then those motors aren't typically designed 
for inexpensive VFDs.

>>That in either event does not seem to be a viable way to spin a 1/2-13
USS tap at say 300 rpms. <<

I believe that most rigid tapping setups with LinuxCNC are done with VFD driven 
spindle motors with some type of encoder attached.

Dave



On 6/14/2015 8:17 PM, Gene Heskett wrote:
> On Sunday 14 June 2015 17:32:07 andy pugh wrote:
>> On 14 June 2015 at 17:14, Gene Heskett  wrote:
>>> So how do we discern the induction motor,totally unsuitable for vfd
>>> drive except near is design rpms, from the synchronous motor at home
>>> on a vfd drive?
>> I think there is a false assumption here. VFDs are _intended_ for
>> driving induction motors. All my machines have squirrel-cage induction
>> motors driven by VFDs on the spindles. The Harrison still has the
>> original motor from 1970.
> Humm, that does not grok with what I understand is the actual motive
> force that turns the induction motor armature.
>
> 1.  The slip angle that causes the current in the armatiure is basically
> a velocity effect.  Reduce the driving frequency from 60 hz to 6hz, and
> one or both of 2 things are going to happen.
>
> 1a: The currents, because the inductance is still the same, now have time
> to rise to destructive, fusing of the wire in the windings levels.  This
> will likely saturate the iron at the same time.
>
> 1b: If the currents are controlled so that they remain the same, then the
> rate of change of the magnetic field is reduced to 10%, inducing only
> 10% of the currents in the squirrel caged armature, with resulting
> severe loss of torque.  Not to 10%, but because the effects are
> additive, but closer to 1% of the torque it can deliver when drven at 60
> HZ.
>
> That in either event does not seem to be a viable way to spin a 1/2-13
> USS tap at say 300 rpms.
>
> 2.  So, do I not understand what I have learned from 65 or 70 years ago,
> or has a new way to drive such an induction motor that cancels or
> defeats the low speed power/torque losses?
>
> Educate me please.
>
> Thanks.
>
> Cheers, Gene Heskett

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Sunday 14 June 2015 17:32:07 andy pugh wrote:
> On 14 June 2015 at 17:14, Gene Heskett  wrote:
> > So how do we discern the induction motor,totally unsuitable for vfd
> > drive except near is design rpms, from the synchronous motor at home
> > on a vfd drive?
>
> I think there is a false assumption here. VFDs are _intended_ for
> driving induction motors. All my machines have squirrel-cage induction
> motors driven by VFDs on the spindles. The Harrison still has the
> original motor from 1970.

Humm, that does not grok with what I understand is the actual motive 
force that turns the induction motor armature.

1.  The slip angle that causes the current in the armatiure is basically 
a velocity effect.  Reduce the driving frequency from 60 hz to 6hz, and 
one or both of 2 things are going to happen.

1a: The currents, because the inductance is still the same, now have time 
to rise to destructive, fusing of the wire in the windings levels.  This 
will likely saturate the iron at the same time.

1b: If the currents are controlled so that they remain the same, then the 
rate of change of the magnetic field is reduced to 10%, inducing only 
10% of the currents in the squirrel caged armature, with resulting 
severe loss of torque.  Not to 10%, but because the effects are 
additive, but closer to 1% of the torque it can deliver when drven at 60 
HZ.

That in either event does not seem to be a viable way to spin a 1/2-13 
USS tap at say 300 rpms.

2.  So, do I not understand what I have learned from 65 or 70 years ago, 
or has a new way to drive such an induction motor that cancels or 
defeats the low speed power/torque losses?

Educate me please.

Thanks.

Cheers, Gene Heskett
-- 
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[andy pugh]

On 14 June 2015 at 17:14, Gene Heskett  wrote:
> So how do we discern the induction motor,totally unsuitable for vfd drive
> except near is design rpms, from the synchronous motor at home on a vfd
> drive?

I think there is a false assumption here. VFDs are _intended_ for
driving induction motors. All my machines have squirrel-cage induction
motors driven by VFDs on the spindles. The Harrison still has the
original motor from 1970.

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[andy pugh]

On 14 June 2015 at 12:55, Steve Stallings  wrote:
> Andy, that is a nice looking setup. I see what I think
> is a rotary joint in the head block. Is that factory
> or shop made?

It's home-made (on the machine itself). It was required for the hobbing setup.

> Is it essential to the clearance needed to mount the motor?

I don't think it was strictly necessary for clearance.

>  What frame size is that motor?

It's a 71 frame on a B14 face.

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Dave Cole]

Here are some new Nema 48's from Baldor.
http://www.electricmotorwholesale.com/BALDOR-MOTORS-3PH-DP.html

Here is Siemens standard motor catalog - if you look at page 2/10 you 
can get an idea of the IEC/Metric frame sizes and relative power outputs.
http://www.motology.co.th/download/motors/%282%29%20Standard%20Motor%20catalog.pdf

On Ebay do a search for "48 frame motor 3 phase". I got almost 100 
hits from that search.  Maybe 1/3 of them were worthwhile items.
I'm not sure how much HP you are looking for.

Your other option is to pickup a used brush DC motor and match that up 
with a DC drive.   A lot of them go pretty cheap because most people are 
trying to get away from brush maintenance.
But DC motors can have 100% torque at very low speeds which is usually 
not possible with a VFD driven AC motor.
Most low HP DC motors tend to be skinny.  :-)

Dave


On 6/14/2015 12:14 PM, Gene Heskett wrote:
> On Sunday 14 June 2015 10:54:57 Dave Cole wrote:
>> Gene,
>>
>> Try looking for a Nema 48 AC motor.   They are almost an inch smaller
>> in diameter.
> That makes perfect sense.  But no search hits until I drop it to Nema 42.
>
>> Also, there are some metric frame motors that are common in Europe
>> that are also smaller in diameter than a Nema 56.
>>
>> http://kurz.com/wp-content/uploads/2014/09/Baldor-NEMA-Frame-Chart.pdf
>>
>> http://www.engineeringtoolbox.com/nema-electrical-motor-frame-dimensio
>> ns-d_1504.html
>>
>> Dave
>>
> I think one of the things that is confusing me is when you or I  think 3
> phase, we are thinking of a hard armature that is in fact a p.m.  So
> while it may have a phase lag due to loading, it is in fact synchronous.
> Such a motor can be driven at stump pulling speeds with full torque
> available just by dropping the drive frequency, and they will do it
> without excessive heating if the invertor is current regulated.  Fading
> only when the rpms doesn't generate a cooling air flow.
>
> But for the average guy peddling what he found on ebay, he has no clue
> how to tell us that THIS motor is in fact an induction motor, and the
> output rpms MUST lag the frequency because that is what generates the
> currents in the armature that make it run.
>
> So how do we discern the induction motor,totally unsuitable for vfd drive
> except near is design rpms, from the synchronous motor at home on a vfd
> drive?
>
> Example:
> Doing a search for a 3 phase motor, the complete first 50 hits are all
> induction, none claim to turn as synchronous speeds. All "slip" some as
> much as 75 rpm from 1800. 1800 or 3600 on 60hz would indicate one we
> might be able to use.
>
>> On 6/14/2015 10:16 AM, Gene Heskett wrote:
>>> On Sunday 14 June 2015 05:06:22 andy pugh wrote:
 On 14 June 2015 at 02:38, Gene Heskett  wrote:
> It does look good, but where can I get an adaptor to mount that
> 56C frame on the GO704?  Or is that my first project, making one?
> ;-)
 What is the existing motor mount?
>>> About an inch smaller OD than a 56C.
>>>
 I adapted my Mini-Mill to a standard 3-phase motor:
 https://picasaweb.google.com/lh/photo/Dk3wsS9o7XJ-N2kfUnESDtMTjNZET
 Ymy PJy0liipFm0?feat=directlink

> At $116 + ship, looks good also. Needs a modbus circuit from lcnc.
> Who has that hardware?
 Just because you can use Modbus it doesn't mean that you must use
 Modbus. Those VFDs all accept analogue voltage, potentiometer and
 current-loop too.
>>> That greatly simplifies that, 5i25 pwm out driving a SpinX1 which I
>>> have.
>>>
>>> Cheers, Gene Heskett
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Sunday 14 June 2015 10:54:57 Dave Cole wrote:
> Gene,
>
> Try looking for a Nema 48 AC motor.   They are almost an inch smaller
> in diameter.

That makes perfect sense.  But no search hits until I drop it to Nema 42.

> Also, there are some metric frame motors that are common in Europe
> that are also smaller in diameter than a Nema 56.
>
> http://kurz.com/wp-content/uploads/2014/09/Baldor-NEMA-Frame-Chart.pdf
>
> http://www.engineeringtoolbox.com/nema-electrical-motor-frame-dimensio
>ns-d_1504.html
>
> Dave
>
I think one of the things that is confusing me is when you or I  think 3 
phase, we are thinking of a hard armature that is in fact a p.m.  So 
while it may have a phase lag due to loading, it is in fact synchronous.  
Such a motor can be driven at stump pulling speeds with full torque 
available just by dropping the drive frequency, and they will do it 
without excessive heating if the invertor is current regulated.  Fading 
only when the rpms doesn't generate a cooling air flow.

But for the average guy peddling what he found on ebay, he has no clue 
how to tell us that THIS motor is in fact an induction motor, and the 
output rpms MUST lag the frequency because that is what generates the 
currents in the armature that make it run.

So how do we discern the induction motor,totally unsuitable for vfd drive 
except near is design rpms, from the synchronous motor at home on a vfd 
drive?

Example:
Doing a search for a 3 phase motor, the complete first 50 hits are all 
induction, none claim to turn as synchronous speeds. All "slip" some as 
much as 75 rpm from 1800. 1800 or 3600 on 60hz would indicate one we 
might be able to use.

> On 6/14/2015 10:16 AM, Gene Heskett wrote:
> > On Sunday 14 June 2015 05:06:22 andy pugh wrote:
> >> On 14 June 2015 at 02:38, Gene Heskett  wrote:
> >>> It does look good, but where can I get an adaptor to mount that
> >>> 56C frame on the GO704?  Or is that my first project, making one?
> >>> ;-)
> >>
> >> What is the existing motor mount?
> >
> > About an inch smaller OD than a 56C.
> >
> >> I adapted my Mini-Mill to a standard 3-phase motor:
> >> https://picasaweb.google.com/lh/photo/Dk3wsS9o7XJ-N2kfUnESDtMTjNZET
> >>Ymy PJy0liipFm0?feat=directlink
> >>
> >>> At $116 + ship, looks good also. Needs a modbus circuit from lcnc.
> >>> Who has that hardware?
> >>
> >> Just because you can use Modbus it doesn't mean that you must use
> >> Modbus. Those VFDs all accept analogue voltage, potentiometer and
> >> current-loop too.
> >
> > That greatly simplifies that, 5i25 pwm out driving a SpinX1 which I
> > have.
> >
> > Cheers, Gene Heskett
>
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Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Dave Cole]

Gene,

Try looking for a Nema 48 AC motor.   They are almost an inch smaller in 
diameter.
Also, there are some metric frame motors that are common in Europe that 
are also smaller in diameter than a Nema 56.

http://kurz.com/wp-content/uploads/2014/09/Baldor-NEMA-Frame-Chart.pdf

http://www.engineeringtoolbox.com/nema-electrical-motor-frame-dimensions-d_1504.html

Dave

On 6/14/2015 10:16 AM, Gene Heskett wrote:
>
> On Sunday 14 June 2015 05:06:22 andy pugh wrote:
>> On 14 June 2015 at 02:38, Gene Heskett  wrote:
>>> It does look good, but where can I get an adaptor to mount that 56C
>>> frame on the GO704?  Or is that my first project, making one? ;-)
>> What is the existing motor mount?
> About an inch smaller OD than a 56C.
>
>> I adapted my Mini-Mill to a standard 3-phase motor:
>> https://picasaweb.google.com/lh/photo/Dk3wsS9o7XJ-N2kfUnESDtMTjNZETYmy
>> PJy0liipFm0?feat=directlink
>>
>>> At $116 + ship, looks good also. Needs a modbus circuit from lcnc.
>>> Who has that hardware?
>> Just because you can use Modbus it doesn't mean that you must use
>> Modbus. Those VFDs all accept analogue voltage, potentiometer and
>> current-loop too.
> That greatly simplifies that, 5i25 pwm out driving a SpinX1 which I have.
>
> Cheers, Gene Heskett

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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Sunday 14 June 2015 09:49:33 Kirk Wallace wrote:
> On 06/14/2015 04:48 AM, Steve Stallings wrote:
> >> -Original Message-
> >> From: Gregg Eshelman [mailto:g_ala...@yahoo.com]
> >> Sent: Sunday, June 14, 2015 4:12 AM
> >
> > 
> >
> >> If it has a 240 option on both primary and secondary, would not
> >> using the 240 taps on both make it a 1:1 so putting 120 in would
> >> get 120 out?
> >
> > Yes the voltage ration will hold. You can even swap the
> > secondary and primary sides but there may be differences
> > of a few percent because the listed voltages include a
> > margin for internal losses.
> >
> > What you cannot safely do is exceed the current rating
> > of any winding even though the total power is within
> > specifications. This is because excess current can
> > saturate the magnetic core which can result in suddenly
> > lower impedance and bad things will happen.
> >
> > In the example that you gave, this would mean that you
> > would only be able to safely get half as much power from
> > the transformer.
>
> Hmmm, I'm wondering if this could be checked easily. Clamp -on
> ammeters are cheap, maybe check the current going in, then compare the
> current going out. At some point the input will start to get much
> higher than the output.

It will do that very quickly in ferrite, such as a toroid, because that 
saturation point is often mirrored to the curie point, and when Ferrite 
goes non-magnetic due to core temps exceeding the curie point, its 
wrecked, magnetic impedance lost.  The next thing is the invertor 
transistors, which usually fail about 100 milliseconds before a fast 
blow fuse can clear.
>
> Temperature might be a indicator too.
>
> (https://en.wikipedia.org/wiki/Saturation_%28magnetic%29)

Cheers, Gene Heskett
-- 
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Sunday 14 June 2015 05:06:22 andy pugh wrote:
> On 14 June 2015 at 02:38, Gene Heskett  wrote:
> > It does look good, but where can I get an adaptor to mount that 56C
> > frame on the GO704?  Or is that my first project, making one? ;-)
>
> What is the existing motor mount?

About an inch smaller OD than a 56C.

> I adapted my Mini-Mill to a standard 3-phase motor:
> https://picasaweb.google.com/lh/photo/Dk3wsS9o7XJ-N2kfUnESDtMTjNZETYmy
>PJy0liipFm0?feat=directlink
>
> > At $116 + ship, looks good also. Needs a modbus circuit from lcnc. 
> > Who has that hardware?
>
> Just because you can use Modbus it doesn't mean that you must use
> Modbus. Those VFDs all accept analogue voltage, potentiometer and
> current-loop too.

That greatly simplifies that, 5i25 pwm out driving a SpinX1 which I have.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Sunday 14 June 2015 05:06:22 andy pugh wrote:
> On 14 June 2015 at 02:38, Gene Heskett  wrote:
> > It does look good, but where can I get an adaptor to mount that 56C
> > frame on the GO704?  Or is that my first project, making one? ;-)
>
> What is the existing motor mount?
> I adapted my Mini-Mill to a standard 3-phase motor:
> https://picasaweb.google.com/lh/photo/Dk3wsS9o7XJ-N2kfUnESDtMTjNZETYmy
>PJy0liipFm0?feat=directlink

I see a small amount hanging over the edge, but I am not sure that head 
is as wide as mine.  You just redrilled the top plate I assume? What the 
hp rating on that one?
>
> > At $116 + ship, looks good also. Needs a modbus circuit from lcnc. 
> > Who has that hardware?
>
> Just because you can use Modbus it doesn't mean that you must use
> Modbus. Those VFDs all accept analogue voltage, potentiometer and
> current-loop too.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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Re: [Emc-users] Suitable transformers = hens teeth

[Kirk Wallace]

On 06/14/2015 04:48 AM, Steve Stallings wrote:
>> -Original Message-
>> From: Gregg Eshelman [mailto:g_ala...@yahoo.com]
>> Sent: Sunday, June 14, 2015 4:12 AM
> 
>>
>> If it has a 240 option on both primary and secondary, would not using
>> the 240 taps on both make it a 1:1 so putting 120 in would
>> get 120 out?
>>
>>
>
> Yes the voltage ration will hold. You can even swap the
> secondary and primary sides but there may be differences
> of a few percent because the listed voltages include a
> margin for internal losses.
>
> What you cannot safely do is exceed the current rating
> of any winding even though the total power is within
> specifications. This is because excess current can
> saturate the magnetic core which can result in suddenly
> lower impedance and bad things will happen.
>
> In the example that you gave, this would mean that you
> would only be able to safely get half as much power from
> the transformer.

Hmmm, I'm wondering if this could be checked easily. Clamp -on ammeters 
are cheap, maybe check the current going in, then compare the current 
going out. At some point the input will start to get much higher than 
the output.

Temperature might be a indicator too.

(https://en.wikipedia.org/wiki/Saturation_%28magnetic%29)

-- 
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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Steve Stallings]

> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com] 
> Sent: Sunday, June 14, 2015 5:06 AM

> 
> What is the existing motor mount?
> I adapted my Mini-Mill to a standard 3-phase motor:
> https://picasaweb.google.com/lh/photo/Dk3wsS9o7XJ-N2kfUnESDtMT
> jNZETYmyPJy0liipFm0?feat=directlink
> 

Andy, that is a nice looking setup. I see what I think
is a rotary joint in the head block. Is that factory
or shop made? Is it essential to the clearance needed
to mount the motor? What frame size is that motor?

Steve Stallings


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Re: [Emc-users] Suitable transformers = hens teeth

[Steve Stallings]

> -Original Message-
> From: Gregg Eshelman [mailto:g_ala...@yahoo.com] 
> Sent: Sunday, June 14, 2015 4:12 AM

> 
> If it has a 240 option on both primary and secondary, would not using 
> the 240 taps on both make it a 1:1 so putting 120 in would 
> get 120 out?
> 
> 

Yes the voltage ration will hold. You can even swap the
secondary and primary sides but there may be differences
of a few percent because the listed voltages include a
margin for internal losses.

What you cannot safely do is exceed the current rating
of any winding even though the total power is within
specifications. This is because excess current can
saturate the magnetic core which can result in suddenly
lower impedance and bad things will happen.

In the example that you gave, this would mean that you
would only be able to safely get half as much power from
the transformer.

Steve Stallings


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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[andy pugh]

On 14 June 2015 at 02:38, Gene Heskett  wrote:

> It does look good, but where can I get an adaptor to mount that 56C frame
> on the GO704?  Or is that my first project, making one? ;-)

What is the existing motor mount?
I adapted my Mini-Mill to a standard 3-phase motor:
https://picasaweb.google.com/lh/photo/Dk3wsS9o7XJ-N2kfUnESDtMTjNZETYmyPJy0liipFm0?feat=directlink

> At $116 + ship, looks good also. Needs a modbus circuit from lcnc.  Who
> has that hardware?

Just because you can use Modbus it doesn't mean that you must use Modbus.
Those VFDs all accept analogue voltage, potentiometer and current-loop too.

-- 
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Re: [Emc-users] Suitable transformers = hens teeth

[Gregg Eshelman]

On 6/13/2015 8:53 AM, Jon Elson wrote:
>
> There are, however, "step down" transformers.  These usually have split
> primary and secondary windings, so you can configure them for 240 or 480
> V on the primary, and 240 or 120 on the secondary.  If you can tolerate
> running it at half voltage, set primary for 240 V and supply 120, and
> then you can get 60 V AC out of the secondary. Or, get 120 V CT on the
> secondary and run through a 2-diode full-wave rectifier to get about 84
> V DC with a capacitor input filter.  You can find these in the multi-KVA
> size.  Often machine tool vultures and industrial surplus places have
> PILES of them.

If it has a 240 option on both primary and secondary, would not using 
the 240 taps on both make it a 1:1 so putting 120 in would get 120 out?


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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Greg Bentzinger]

- Original Message -
From: Steve Stallings 
To: 'Greg Bentzinger' ; 'Enhanced Machine Controller 
(EMC)' 
Cc: 
Sent: Saturday, June 13, 2015 6:10 PM
Subject: RE: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

> -Original Message-

> From: Greg Bentzinger [mailto:skullwo...@yahoo.com] 
> Sent: Saturday, June 13, 2015 7:31 PM

> 
> -- ^ ^ ^ ^ ^ ^ No idea where you came up with this - never 
> said anything about water cooling or trying to use a 24K 
> router type spindle.
> 
> I actually said a LOWER rpm rated motor (@60Hz)- such as a 
> 1725 or below.
> 
> I dropped "56C 1.5hp 3ph" into ebay search and the first 
> thing that popped up was ebay item#4601799582
> 
> Buy it now price of $139 - I'm sure a better deal can be 
> found, but this was the first item that popped up
> 
> New 56C/TEFC 1725rpm 1.5hp 5/8" output shaft inverter rated, 
> 10:1 Variable torque, 2:1 Constant torque
> 

Careful. I have looked for motors to fit a G0704 before and found 
very few that would fit, certainly not a 56C frame. There some
square BLDC motors that will fit well.

Steve Stallings



Well understood Steve.

I look at it this way - once you jump in with both feet deciding to take an off 
the shelf manual machine and do a CNC conversion using parts from more than 1 
vendor you have left the reservation and are on your own.

The expectation should be that nothing will "just fit". True most things will 
work as expect out of the box, but alot of that comes from people doing there 
homework and knowing what they really need. Its all part of building a CNC.

Many of the benchtop mills when a non-OEM type spindle motor is replaced 
require some sort of adapter plate with brackets or standoffs and often replace 
the existing belt drive with a different setup. A 3ph motor will be bigger and 
heavy compared to a DC unit, at least the added mass will help damp cutting 
vibration in the head.


I bought one of the first IH large ring mills after Aaron sold IH to Gene 
Spada. A common "upgrade" people were doing was buying the 3450rpm motors to 
replace the slow and noisy OEM Chi-com motor and bringing the geared head mill 
up to 3600rpm capability. This upgrade required an adapter plate and that the 
motor output shaft be turned down and a new key slot milled. I bought a new 
Baldor 3450 motor, then later a more heavy duty motor rated at 2400rpm and 
since I planned to use a VFD anyway vrs my limited 3ph coming off my 10hp 
rotary phase converter. With the VFD I could push the rpm to 5K, though 
extended running at that speed would cause excessive heat and foam in the 
gearbox. IH ran the in house mill @ 6000rpm, I didn't want to be replacing 
bearings all the time, so 5K is my limit.


Automation Technologies tried the BLDC spindle motor deal with the KL-2200 and 
KL-1160 which are square BLDC 400-6000rpm motors - its just that actual end 
user reports have been far from impressive. The price is also ultra premo @ 
$699 and I can get a better industrail motor and VFD that I can work on without 
having to guess at vague chi documentation and ZERO factory support. If it 
would actually work it would be worth it to some owners.

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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Saturday 13 June 2015 21:49:38 Ken Strauss wrote:
> I have placed one order with them without a problem; the supplied
> motor was exactly as advertised. Unfortunately it was not what I
> needed! Note to self: "Learn to read!"

BTDT Ken, had to chuckle at myself later.  After I got done chewing my 
own butt that is.

Its actually been quite a spell since then, and things do improve 
sometimes.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth

[Ken Strauss]

I have placed one order with them without a problem; the supplied motor was
exactly as advertised. Unfortunately it was not what I needed! Note to self:
"Learn to read!"

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@wdtv.com]
> Sent: Saturday, June 13, 2015 9:06 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Suitable transformers = hens teeth
>
> On Saturday 13 June 2015 18:04:14 jeremy youngs wrote:
> > Surplus sales of Nebraska
>
> I have dealt with them before and that has made me a bit gunshy.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page <http://geneslinuxbox.net:6309/gene>
>
>

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Saturday 13 June 2015 20:10:20 Steve Stallings wrote:
> > -Original Message-
> > From: Greg Bentzinger [mailto:skullwo...@yahoo.com]
> > Sent: Saturday, June 13, 2015 7:31 PM
>
> 
>
> > -- ^ ^ ^ ^ ^ ^ No idea where you came up with this - never
> > said anything about water cooling or trying to use a 24K
> > router type spindle.
> >
> > I actually said a LOWER rpm rated motor (@60Hz)- such as a
> > 1725 or below.
> >
> > I dropped "56C 1.5hp 3ph" into ebay search and the first
> > thing that popped up was ebay item#4601799582
> >
> > Buy it now price of $139 - I'm sure a better deal can be
> > found, but this was the first item that popped up
> >
> > New 56C/TEFC 1725rpm 1.5hp 5/8" output shaft inverter rated,
> > 10:1 Variable torque, 2:1 Constant torque
>
> Careful. I have looked for motors to fit a G0704 before and found
> very few that would fit, certainly not a 56C frame. There some
> square BLDC motors that will fit well.
>
That was my stumbling block too, Steve.  Not that adaptors can't be made 
and I have a decent stock of 4"x.500" 7075t4 on hand at should work 
nicely.

> Steve Stallings
>
>
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Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Gene Heskett]

On Saturday 13 June 2015 19:31:20 Greg Bentzinger wrote:
> Replies inline
>
>
> Quoting - Message: 7Date: Sat, 13 Jun 2015 14:42:37 -0400
> From: Gene Heskett 
> Subject: Re: [Emc-users] was  Suitable transformers = hens teeth
> To: emc-users@lists.sourceforge.net
> Message-ID: <201506131442.37277.ghesk...@wdtv.com>
> Content-Type: Text/Plain;  charset="iso-8859-1"
>
> On Saturday 13 June 2015 12:05:11 Greg Bentzinger wrote:
> > Gene;
> >
> > We really need to break your DC motor fixation. If you think PCW's
> > 5i25 is neat just wait until you start using a VFD controlled
> > spindle.
> >
> > Odds are that a better replacement motor and VFD will cost near the
> > same of what your planning to build to support that marginal OEM DC
> > motor.
>
> That marginal motor is easily replaceable with something with serious
> grunt that is right at home at 5 grand at the armature, perhaps 1100
> at the spindle.
>
> The power supply in each case is the majority of the cost, but with
> Jon's PWM servo driver, slightly modified, I've found I CAN manhandle
> a treadmill motor fast enough to do rigid tapping, with grunt enough
> to drive the tap.  None of those vfd things, designed to turn at 24k
> rpms for engraving, can even begin to drive a 4-40 tap, let alone a
> 1/2-13. And for those situations where I don't have the grunt to do it
> in one pass, I have already written pack tapping stuff to wrap up the
> G33.1 with.
>
> > I have several great treadmill motors and some motor controllers for
> > them,
>
> motor controllers intended for a treadmill motor are incapable of
> doing the control needed.  Jon's pwm servo amp, with increased wire
> gauge in the toroids, can turn that treadmill motor around from 3 g's
> at the artmature, 300 at the spindle, in a time frame quiter
> comparable to the vfd if allowances for the flying weight to be
> reversed are taken into consideration.  On my lathe, that flying
> weight is well above 10lbs as its swinging a 5" 4 jaw chuck.
> But that is not using the treadmill controller, which cannot actively
> stop the motor.  Jons PWM Servo amp can.
>
> > but trying to keep fine tune of RPM vrs load is a hemroid and
> > using those controls for reversing just isn't practical. Then there
> > was the heating issue of running the motor at lower RPMs.
>
> I no longer try to subdue those BBLB controllers, they decorate a
> shelf now.  Jons PWM Servo amp is a breath of fresh air in comparison.
>
> > I would get a 1.5 or 2hp motor with a lower 60Hz rpm spec then over
> > speed it as needed so you have plenty of low rpm power.
>
> And just how do I spin a 2.2kw water cooled, 24k revs motor at 250
> rpm's
>
> and have enough torque to throw a .015"x.015"x3/8" chip 2 feet away?
>
> -- ^ ^ ^ ^ ^ ^ No idea where you came up with this - never said
> anything about water cooling or trying to use a 24K router type
> spindle.

Because an ebay search for 2kw vfd spindles only returned such engraving 
motors with the exception of a $3700 head for a bridgeport.

> I actually said a LOWER rpm rated motor (@60Hz)- such as a 1725 or
> below.
>
> I dropped "56C 1.5hp 3ph" into ebay search and the first thing that
> popped up was ebay item#4601799582
>
> Buy it now price of $139 - I'm sure a better deal can be found, but
> this was the first item that popped up

It does look good, but where can I get an adaptor to mount that 56C frame 
on the GO704?  Or is that my first project, making one? ;-)

How about this for a driver?


At $116 + ship, looks good also. Needs a modbus circuit from lcnc.  Who 
has that hardware?

> New 56C/TEFC 1725rpm 1.5hp 5/8" output shaft inverter rated, 10:1
> Variable torque, 2:1 Constant torque
>
> Direct drive 1:1 this motor would provide:
>
> 172.5 rpm @ 6Hz
> 1725  rpm @ 60Hz - Nominal motor spec - Optimal
>
> 3450  rpm @ 120Hz
> 5170  rpm @ 180Hz
> 5750  rpm @ 200Hz
>
> I would not trust the Grizzly spindle bearings @ 6000 rpm unless I had
> removed, checked fit, regreased and set the bearing preload.
>
And TBT, these are horrible, 15 minutes no load at 1600 revs raised the 
quill temp 25F on my IR thermometer.  I am repeating the breakin 
procedure, but I doubt if it will do much good, I believe them to be 
seriously preloaded way too high.

IMO, decent bearings are a must, but you do not get those in a $850 
machine. So no complaints to Grizzly unless I can't find decent bearings 
a year down the log.

> Now if you got ambitious and wanted to do a step-pulley drive:
>
> Underdrive the spindle 1:0.5
>
> 86.25 rpm @ 6Hz
> 862.5 rpm @ 60Hz - Nominal
> 1725  rpm @ 120Hz
> 2587  rpm @ 180Hz
> 2875  rpm @ 200Hz
>
> Overdrive the spindle 2:1
>
> 345  rpm @ 6Hz
> 3450 rpm @ 60Hz - Nominal
> 6900 rpm @ 120Hz
>
> > On a side note you would still have the Pico drive available for
> > your old mill so little things like engraving could still be done on
>

Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Saturday 13 June 2015 18:04:14 jeremy youngs wrote:
> Surplus sales of Nebraska

I have dealt with them before and that has made me a bit gunshy.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Saturday 13 June 2015 05:32:34 andy pugh wrote:
> On 13 June 2015 at 00:09, Gene Heskett  wrote:
> > But 1kw and up isolation cans are both scarce, and north of a $100
> > bill pricy at least on fleabay.
>
> eBay UK is awash with "site transformers" such as this
> http://www.ebay.com/itm/British-Made-Caroll-Meynell-3-3kva-site-transf
>ormer-/121656911146
>
> They are used for isolation of power tools on building sites. Second
> hand ones go for less, of course:
> As you can see, UK ones are 240V to 110 step-down. Is there not a
> 110-110V version used on US building sites?

Extremely rarely Andy.  TBE, I have never seen one.  Usually the power 
folks set a pole and put a meter box with a bunch of 3 prong duplexes on 
it & everyone runs their personal drop cords to the pole.

Really large sites might have 8 or 10 such poles.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Steve Stallings]

> -Original Message-
> From: Greg Bentzinger [mailto:skullwo...@yahoo.com] 
> Sent: Saturday, June 13, 2015 7:31 PM

> 
> -- ^ ^ ^ ^ ^ ^ No idea where you came up with this - never 
> said anything about water cooling or trying to use a 24K 
> router type spindle.
> 
> I actually said a LOWER rpm rated motor (@60Hz)- such as a 
> 1725 or below.
> 
> I dropped "56C 1.5hp 3ph" into ebay search and the first 
> thing that popped up was ebay item#4601799582
> 
> Buy it now price of $139 - I'm sure a better deal can be 
> found, but this was the first item that popped up
> 
> New 56C/TEFC 1725rpm 1.5hp 5/8" output shaft inverter rated, 
> 10:1 Variable torque, 2:1 Constant torque
> 

Careful. I have looked for motors to fit a G0704 before and found 
very few that would fit, certainly not a 56C frame. There some
square BLDC motors that will fit well.

Steve Stallings


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Re: [Emc-users] Suitable transformers = hens teeth (Gene Heskett)

[Greg Bentzinger]

Replies inline


Quoting - Message: 7Date: Sat, 13 Jun 2015 14:42:37 -0400
From: Gene Heskett 
Subject: Re: [Emc-users] was  Suitable transformers = hens teeth
To: emc-users@lists.sourceforge.net
Message-ID: <201506131442.37277.ghesk...@wdtv.com>
Content-Type: Text/Plain;  charset="iso-8859-1"

On Saturday 13 June 2015 12:05:11 Greg Bentzinger wrote:
> Gene;
>
> We really need to break your DC motor fixation. If you think PCW's
> 5i25 is neat just wait until you start using a VFD controlled spindle.
>
> Odds are that a better replacement motor and VFD will cost near the
> same of what your planning to build to support that marginal OEM DC
> motor.
That marginal motor is easily replaceable with something with serious
grunt that is right at home at 5 grand at the armature, perhaps 1100 at
the spindle.

The power supply in each case is the majority of the cost, but with Jon's
PWM servo driver, slightly modified, I've found I CAN manhandle a
treadmill motor fast enough to do rigid tapping, with grunt enough to
drive the tap.  None of those vfd things, designed to turn at 24k rpms
for engraving, can even begin to drive a 4-40 tap, let alone a 1/2-13. 
And for those situations where I don't have the grunt to do it in one
pass, I have already written pack tapping stuff to wrap up the G33.1
with.
>
> I have several great treadmill motors and some motor controllers for
> them,
motor controllers intended for a treadmill motor are incapable of doing
the control needed.  Jon's pwm servo amp, with increased wire gauge in
the toroids, can turn that treadmill motor around from 3 g's at the
artmature, 300 at the spindle, in a time frame quiter comparable to the
vfd if allowances for the flying weight to be reversed are taken into
consideration.  On my lathe, that flying weight is well above 10lbs as
its swinging a 5" 4 jaw chuck.
But that is not using the treadmill controller, which cannot actively
stop the motor.  Jons PWM Servo amp can.

> but trying to keep fine tune of RPM vrs load is a hemroid and
> using those controls for reversing just isn't practical. Then there
> was the heating issue of running the motor at lower RPMs.

I no longer try to subdue those BBLB controllers, they decorate a shelf
now.  Jons PWM Servo amp is a breath of fresh air in comparison.

> I would get a 1.5 or 2hp motor with a lower 60Hz rpm spec then over
> speed it as needed so you have plenty of low rpm power.

And just how do I spin a 2.2kw water cooled, 24k revs motor at 250 rpm's

and have enough torque to throw a .015"x.015"x3/8" chip 2 feet away?

-- ^ ^ ^ ^ ^ ^ No idea where you came up with this - never said anything about 
water cooling or trying to use a 24K router type spindle.

I actually said a LOWER rpm rated motor (@60Hz)- such as a 1725 or below.

I dropped "56C 1.5hp 3ph" into ebay search and the first thing that popped up 
was ebay item#4601799582

Buy it now price of $139 - I'm sure a better deal can be found, but this was 
the first item that popped up

New 56C/TEFC 1725rpm 1.5hp 5/8" output shaft inverter rated, 10:1 Variable 
torque, 2:1 Constant torque

Direct drive 1:1 this motor would provide:

172.5 rpm @ 6Hz
1725  rpm @ 60Hz - Nominal motor spec - Optimal

3450  rpm @ 120Hz
5170  rpm @ 180Hz
5750  rpm @ 200Hz

I would not trust the Grizzly spindle bearings @ 6000 rpm unless I had removed, 
checked fit, regreased and set the bearing preload.

Now if you got ambitious and wanted to do a step-pulley drive:

Underdrive the spindle 1:0.5

86.25 rpm @ 6Hz
862.5 rpm @ 60Hz - Nominal
1725  rpm @ 120Hz
2587  rpm @ 180Hz
2875  rpm @ 200Hz

Overdrive the spindle 2:1

345  rpm @ 6Hz
3450 rpm @ 60Hz - Nominal
6900 rpm @ 120Hz

> On a side note you would still have the Pico drive available for your
> old mill so little things like engraving could still be done on it.
>
Its actually on my lathe.  Thats a PMDX-106 on the mill, driving a 1.8
amp rated, 2500 revs at the spindle on the mill.  The OEM pass hexfet
died years ago, and was replaced by one from a dead computer psu. 
Nearly zero heating now, it could do a 400 watt motor just fine if I
ever get around to using the motor I took out of the lathe.

> That 240V is just waiting to be used...

I found a toroid to fix that last night.  Admittedly, the PMDC motor has
brushes to wear out, where the vfd doesn't.  But where do I find the
power to spin a 1/4" upcut solid carbide tool with that vfd driven
pipsqueak?  Can that vfd and a water cooled motor do 47hz output and

turn a 1/4-32 tap 180 revs in steel?

I'm sure you would have no problems tapping @ about 300 rpm.

Why piddle around with a 1/4" endmill when a 3/8" is a better buy - save the 
1/4" for finishing the corners.

I had no idea what could really be done with the tooling I all ready had until 
I went to the WESTEC tool show and watched other machines plow through metal 
like butter. I was still thinking small.

Good question that.



Cheers, Gene Heskett

End quote & reply - Greg



BTW the motor picked would put you clo

Re: [Emc-users] Suitable transformers = hens teeth

[jeremy youngs]

Surplus sales of Nebraska
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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Saturday 13 June 2015 10:49:18 Jon Elson wrote:
> On 06/13/2015 04:32 AM, andy pugh wrote:
> > On 13 June 2015 at 00:09, Gene Heskett  wrote:
> >> But 1kw and up isolation cans are both scarce, and north of a $100
> >> bill pricy at least on fleabay.
> >
> > eBay UK is awash with "site transformers" such as this
> > http://www.ebay.com/itm/British-Made-Caroll-Meynell-3-3kva-site-tran
> >sformer-/121656911146
> >
> > They are used for isolation of power tools on building sites. Second
> > hand ones go for less, of course:
> > As you can see, UK ones are 240V to 110 step-down. Is there not a
> > 110-110V version used on US building sites?
>
> No.  I've always thought the balanced 110 V job site transformers were
> a really good idea.  As far as I know, they are ONLY used in the UK.
> Never, ever seen anything like that at a US job site.  They probably
> do use GFCI protection today.
>
> Jon
>
I have a friend who built a recording studio about a decade back, but 
couldn't afford balanced audio everywhere.  So the whole control room is 
on a 240-120CT transformer, with the CT grounded so its 63-0-63.  Wind 
up a mic gain on that Mackay single ended input board and its pure white 
noise, and not much of that.  Humm out of it is like 100+ db down.

He had a hell of a time convincing the inspectors to pass it though.  
Seems the NEC doesn't address such usage.

I was dubious at first, but I'm a believer now.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Saturday 13 June 2015 10:46:42 Jon Elson wrote:
> On 06/12/2015 10:02 PM, Gene Heskett wrote:
> > I am well aware of that lack of a Santa Jack, but we're talking
> > about a couple kilowatts worth of iron & copper to have a CCS rated
> > setup. I don't mind paying some north of a $150 bill, but even at
> > that, the selection on fleabay is limited, or poorly described.
>
> Have you checked Hammond?  They have a listing of everything they
> make, I think available as a link through Mouser.  These are big
> toroids, and they have a couple models in the 1.5 KVA size.
>
> Jon
>
I saw quite a few of them on fleabay, but the tendency to just list the 
hammond part number, expecting us to have a broswer page open to the 
Hammon site so we can x-ref to volts & amps, disposes me to skip those 
listings.  Hammond I note, seems to have purchased the Peter Dahl 
production line when Peter retired.  Thats good news to us broadcasters 
who have been getting our replacements for 50 year old iron from Peter 
for decades.

The toroid I bought, 2000va, rates as 18.7 amps per 120 volt winding.  
That ought to be able to get a motors attention.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Saturday 13 June 2015 13:20:19 Ken Strauss wrote:
> Aren't these often auto-transformers which provide no isolation
> between input and output?

Thats what I am careful to check.  The one I bought is two separate 120 
volt windings according to the label.  And I may unwind a few turns from 
the one I use as the secondary.  The fw bridge rectified output needs to 
lose 25 volts to be about right.  No biggie. Worst problem is that it 
weighs a hair north of 22kg. 28 shipped.

> > -Original Message-
> > From: Jon Elson [mailto:jonelson...@gmail.com]
> > Sent: Saturday, June 13, 2015 10:53 AM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] Suitable transformers = hens teeth
> >
> >
> > There are, however, "step down" transformers.  These usually have
> > split primary and secondary windings, so you can configure them for
> > 240 or 480 V on the primary, and 240 or 120 on the secondary.  If
> > you can tolerate
>
> running
>
> > it at half voltage, set primary for 240 V and supply 120, and then
> > you can
>
> get 60
>
> > V AC out of the secondary. Or, get 120 V CT on the secondary and run
>
> through
>
> > a 2-diode full-wave rectifier to get about 84 V DC with a capacitor
> > input
>
> filter.

That would be a bit light of ideal but probably usasble.

I usually use a fw bridge, its its less ohmic heating in the transformer.  
Details... ;-)

> > You can find these in the multi-KVA size.  Often machine tool
> > vultures and industrial surplus places have PILES of them.

Which they don't seem to list on fleabay.

> > Jon
>
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Cheers, Gene Heskett
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Re: [Emc-users] Suitable transformers = hens teeth

[Ken Strauss]

Aren't these often auto-transformers which provide no isolation between
input and output?

> -Original Message-
> From: Jon Elson [mailto:jonelson...@gmail.com]
> Sent: Saturday, June 13, 2015 10:53 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Suitable transformers = hens teeth
>
>
> There are, however, "step down" transformers.  These usually have split
> primary and secondary windings, so you can configure them for 240 or 480 V
> on the primary, and 240 or 120 on the secondary.  If you can tolerate
running
> it at half voltage, set primary for 240 V and supply 120, and then you can
get 60
> V AC out of the secondary. Or, get 120 V CT on the secondary and run
through
> a 2-diode full-wave rectifier to get about 84 V DC with a capacitor input
filter.
> You can find these in the multi-KVA size.  Often machine tool vultures and
> industrial surplus places have PILES of them.
>
> Jon
>
>

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Re: [Emc-users] Suitable transformers = hens teeth

[Greg Bentzinger]

Gene;

We really need to break your DC motor fixation. If you think PCW's 5i25 is neat 
just wait until you start using a VFD controlled spindle.

Odds are that a better replacement motor and VFD will cost near the same of 
what your planning to build to support that marginal OEM DC motor.

I have several great treadmill motors and some motor controllers for them, but 
trying to keep fine tune of RPM vrs load is a hemroid and using those controls 
for reversing just isn't practical. Then there was the heating issue of running 
the motor at lower RPMs.

I would get a 1.5 or 2hp motor with a lower 60Hz rpm spec then over speed it as 
needed so you have plenty of low rpm power.

On a side note you would still have the Pico drive available for your old mill 
so little things like engraving could still be done on it.

That 240V is just waiting to be used...

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Re: [Emc-users] Suitable transformers = hens teeth

[Jon Elson]

There are, however, "step down" transformers.  These usually have split 
primary and secondary windings, so you can configure them for 240 or 480 
V on the primary, and 240 or 120 on the secondary.  If you can tolerate 
running it at half voltage, set primary for 240 V and supply 120, and 
then you can get 60 V AC out of the secondary. Or, get 120 V CT on the 
secondary and run through a 2-diode full-wave rectifier to get about 84 
V DC with a capacitor input filter.  You can find these in the multi-KVA 
size.  Often machine tool vultures and industrial surplus places have 
PILES of them.

Jon

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Re: [Emc-users] Suitable transformers = hens teeth

[Jon Elson]

On 06/13/2015 04:32 AM, andy pugh wrote:
> On 13 June 2015 at 00:09, Gene Heskett  wrote:
>> But 1kw and up isolation cans are both scarce, and north of a $100 bill
>> pricy at least on fleabay.
> eBay UK is awash with "site transformers" such as this
> http://www.ebay.com/itm/British-Made-Caroll-Meynell-3-3kva-site-transformer-/121656911146
>
> They are used for isolation of power tools on building sites. Second
> hand ones go for less, of course:
> As you can see, UK ones are 240V to 110 step-down. Is there not a
> 110-110V version used on US building sites?
>
No.  I've always thought the balanced 110 V job site transformers were a 
really good idea.  As far as I know, they are ONLY used in the UK.  
Never, ever seen anything like that at a US job site.  They probably do 
use GFCI protection today.

Jon


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Re: [Emc-users] Suitable transformers = hens teeth

[Jon Elson]

On 06/12/2015 10:02 PM, Gene Heskett wrote:
> I am well aware of that lack of a Santa Jack, but we're talking about 
> a couple kilowatts worth of iron & copper to have a CCS rated setup. I 
> don't mind paying some north of a $150 bill, but even at that, the 
> selection on fleabay is limited, or poorly described.
Have you checked Hammond?  They have a listing of everything they make, 
I think available as a link through Mouser.  These are big toroids, and 
they have a couple models in the 1.5 KVA size.

Jon

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Re: [Emc-users] Suitable transformers = hens teeth

[andy pugh]

On 13 June 2015 at 00:09, Gene Heskett  wrote:
> But 1kw and up isolation cans are both scarce, and north of a $100 bill
> pricy at least on fleabay.

eBay UK is awash with "site transformers" such as this
http://www.ebay.com/itm/British-Made-Caroll-Meynell-3-3kva-site-transformer-/121656911146

They are used for isolation of power tools on building sites. Second
hand ones go for less, of course:
As you can see, UK ones are 240V to 110 step-down. Is there not a
110-110V version used on US building sites?

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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Friday 12 June 2015 23:22:49 Chris Radek wrote:
> On Fri, Jun 12, 2015 at 07:09:26PM -0400, Gene Heskett wrote:
> > But 1kw and up isolation cans are both scarce, and north of a $100
> > bill pricy at least on fleabay.
>
> Check hgr, for example:
>
> http://www.hgrinc.com/productDetail/Electrical/USED-EGS-TRANSFORMER/02
>150100059
>
> I think it says PRIMARY VOLTS 120/-/277, whatever that means
>
> Cheap and at 30lb it's pretty shippable.  They have lots to choose
> from.

Looks pretty ratty.  And I think, if I can get into ebay, I've found a 
big ugly but quiet toroid of 2KW rating.  Ebay isn't co-operating.

If I can get to the paypal button, I know that works.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Friday 12 June 2015 23:02:32 Gene Heskett wrote:
> On Friday 12 June 2015 22:06:16 Jack Coats wrote:
> > Yes Gene, there is no santa clause, especially when you are talking
> > about copper.  Just as a raw material it is pretty pricy.
> >
> > In the past I just got a couple of matched transformers 120VAC to
> > whatever, and put the secondaries together.
> > It makes a good isolation transformer when set up back to back.
>
> At double the iron & I2R losses though.  I'd druther have it on one
> core.
>
> > Good transformers are never cheap.
>
> Depends.  When Peter Dahl was winding stuff for us broadcasters 20
> years ago, I thought he did a quite reasonable job of selling me a
> modern, grain oriented steel core replacement that was 1/2 the size of
> the original that smoked, the smaller size made possible by the
> improved steel for laminations compared to what was in the originals
> in 1956, when I needed it in 1999. I fully expected to have to pay
> twice what he asked, considering he was winding it from scratch using
> the old GE drawings.  And he had it on site in 4 days!
>
> I am well aware of that lack of a Santa Jack, but we're talking about
> a couple kilowatts worth of iron & copper to have a CCS rated setup. I
> don't mind paying some north of a $150 bill, but even at that, the
> selection on fleabay is limited, or poorly described.  One 1.5kw
> toroid looked promising, but the guy may be blowing smoke, no way to
> tell from his description.  I might send him a msg tomorrow to see if
> he has any more data on it.  Good sized, weighs in just short of 40
> lbs, so I don't doubt the 1.5KW rating.  But the windings description
> is sorely lacking in details.
>
> Heck, something out of an old microwave wound on an EI core could
> probably have the high voltage winding recycled & replaced with 8
> gauge enough for what I need.  Some stepdown, say 25-30%  would be ok
> as I'd like to have about 105-110 volts out of a bridge rectifier into
> a 75,000 uf cap or 2.  Those I have several of already.  Surge rated
> at 150. They seem to tolerate the back dump into the supply when
> slowing that 1 hp motor ok.
>
> If I sounded like I was looking to get lucky I'm sorry.
>
> > On Fri, Jun 12, 2015 at 6:09 PM, Gene Heskett 

And I may have found one I can use, now if ebay would just let me login. 
&^#@*&*(+
>
> wrote:
> > > Hi all;
> > >
> > > In laying out how I am going to cnc this GO704, its apparent that
> > > the scr or triac board it comes with to control a motor of
> > > undetermined power, rated variously as 750 watts, 1kw, or needing
> > > 12 amps from the line. None of which groks, but welcome to chinese
> > > specs seems to be the operative response. :)
> > >
> > > Anyway, since Jon's pwm servo amplifier worked so well on my
> > > lathe, and its theoretically capable of that sort of power (20
> > > amps at 160 volts IAACS), my mind is made up to use it again.  But
> > > its I/O is not all isolated so it must have an isolated power
> > > supply.
> > >
> > > But 1kw and up isolation cans are both scarce, and north of a $100
> > > bill pricy at least on fleabay.
> > >
> > > Has anyone got something laying around getting dusty that could
> > > serve as a 120 to 120, or 240 -> 120 isolation, and that you might
> > > be able to part with?  I have 240 just 7 feet away from where I
> > > have it parked so a stepdown would work just as well and would
> > > help balance the load.
> > >
> > > Send me PM's with what it is & how much you'd need and lets see if
> > > we can deal?
> > >
> > > Thanks.
>
> Cheers, Gene Heskett

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth

[Chris Radek]

On Fri, Jun 12, 2015 at 07:09:26PM -0400, Gene Heskett wrote:
> 
> But 1kw and up isolation cans are both scarce, and north of a $100 bill 
> pricy at least on fleabay.

Check hgr, for example:

http://www.hgrinc.com/productDetail/Electrical/USED-EGS-TRANSFORMER/02150100059

I think it says PRIMARY VOLTS 120/-/277, whatever that means

Cheap and at 30lb it's pretty shippable.  They have lots to choose
from.


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Re: [Emc-users] Suitable transformers = hens teeth

[Gene Heskett]

On Friday 12 June 2015 22:06:16 Jack Coats wrote:
> Yes Gene, there is no santa clause, especially when you are talking
> about copper.  Just as a raw material it is pretty pricy.
>
> In the past I just got a couple of matched transformers 120VAC to
> whatever, and put the secondaries together.
> It makes a good isolation transformer when set up back to back.
>
At double the iron & I2R losses though.  I'd druther have it on one core.

> Good transformers are never cheap.

Depends.  When Peter Dahl was winding stuff for us broadcasters 20 years 
ago, I thought he did a quite reasonable job of selling me a modern, 
grain oriented steel core replacement that was 1/2 the size of the 
original that smoked, the smaller size made possible by the improved 
steel for laminations compared to what was in the originals in 1956, 
when I needed it in 1999. I fully expected to have to pay twice what he 
asked, considering he was winding it from scratch using the old GE 
drawings.  And he had it on site in 4 days!

I am well aware of that lack of a Santa Jack, but we're talking about a 
couple kilowatts worth of iron & copper to have a CCS rated setup. I 
don't mind paying some north of a $150 bill, but even at that, the 
selection on fleabay is limited, or poorly described.  One 1.5kw toroid 
looked promising, but the guy may be blowing smoke, no way to tell from 
his description.  I might send him a msg tomorrow to see if he has any 
more data on it.  Good sized, weighs in just short of 40 lbs, so I don't 
doubt the 1.5KW rating.  But the windings description is sorely lacking 
in details.

Heck, something out of an old microwave wound on an EI core could 
probably have the high voltage winding recycled & replaced with 8 gauge 
enough for what I need.  Some stepdown, say 25-30%  would be ok as I'd 
like to have about 105-110 volts out of a bridge rectifier into a 75,000 
uf cap or 2.  Those I have several of already.  Surge rated at 150.  
They seem to tolerate the back dump into the supply when slowing that 1 
hp motor ok.

If I sounded like I was looking to get lucky I'm sorry.

> On Fri, Jun 12, 2015 at 6:09 PM, Gene Heskett  
wrote:
> > Hi all;
> >
> > In laying out how I am going to cnc this GO704, its apparent that
> > the scr or triac board it comes with to control a motor of
> > undetermined power, rated variously as 750 watts, 1kw, or needing 12
> > amps from the line. None of which groks, but welcome to chinese
> > specs seems to be the operative response. :)
> >
> > Anyway, since Jon's pwm servo amplifier worked so well on my lathe,
> > and its theoretically capable of that sort of power (20 amps at 160
> > volts IAACS), my mind is made up to use it again.  But its I/O is
> > not all isolated so it must have an isolated power supply.
> >
> > But 1kw and up isolation cans are both scarce, and north of a $100
> > bill pricy at least on fleabay.
> >
> > Has anyone got something laying around getting dusty that could
> > serve as a 120 to 120, or 240 -> 120 isolation, and that you might
> > be able to part with?  I have 240 just 7 feet away from where I have
> > it parked so a stepdown would work just as well and would help
> > balance the load.
> >
> > Send me PM's with what it is & how much you'd need and lets see if
> > we can deal?
> >
> > Thanks.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Suitable transformers = hens teeth

[Jack Coats]

Yes Gene, there is no santa clause, especially when you are talking
about copper.  Just as a raw material it is pretty pricy.

In the past I just got a couple of matched transformers 120VAC to whatever,
and put the secondaries together.
It makes a good isolation transformer when set up back to back.

Good transformers are never cheap.



On Fri, Jun 12, 2015 at 6:09 PM, Gene Heskett  wrote:

> Hi all;
>
> In laying out how I am going to cnc this GO704, its apparent that the scr
> or triac board it comes with to control a motor of undetermined power,
> rated variously as 750 watts, 1kw, or needing 12 amps from the line.
> None of which groks, but welcome to chinese specs seems to be the
> operative response. :)
>
> Anyway, since Jon's pwm servo amplifier worked so well on my lathe, and
> its theoretically capable of that sort of power (20 amps at 160 volts
> IAACS), my mind is made up to use it again.  But its I/O is not all
> isolated so it must have an isolated power supply.
>
> But 1kw and up isolation cans are both scarce, and north of a $100 bill
> pricy at least on fleabay.
>
> Has anyone got something laying around getting dusty that could serve as
> a 120 to 120, or 240 -> 120 isolation, and that you might be able to
> part with?  I have 240 just 7 feet away from where I have it parked so a
> stepdown would work just as well and would help balance the load.
>
> Send me PM's with what it is & how much you'd need and lets see if we can
> deal?
>
> Thanks.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page 
>
>
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"Anyone who has never made a mistake, has never tried anything new." -
Albert Einstein
"You don't manage people; you manage things. You lead people." - Admiral
Grace Hopper, USN
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