Re: [Emc-users] pressure equalizer method around ball nut

[Peter Blodow]

If you ever tried to spot-weld two alu sheets, the welder developing 
about 1 volt, it will show you that it is a question of voltage to break 
through the oxide layer. After tat, you have conductivity. In order to 
spot weld, scratch the surfaces hard with a rotating steel brush, after 
that you have about 1 sec. for the welding.
Alu surfaces oxidise and thus the area in the vicinity of the contact 
gets smaller. This gives a rising current density at the contact spot. 
Current through a resistance gives cause to heating until the hole 
contact area burns up or melts down, if there is enough power delivered 
by the wires.

Peter

Am 07.10.2016 22:05, schrieb andy pugh:
> On 7 October 2016 at 20:55, Przemek Klosowski
>  wrote:
>> If the alumina layer is thickened (e.g. by anodization), the aluminum
>> objects will be isolated;
> I will also note the apparent conductivity of my anodized
> solder-sucker. But that is probably a think anodised layer, not one
> intended for isolation.
>


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Re: [Emc-users] pressure equalizer method around ball nut

[Gene Heskett]

On Saturday 08 October 2016 15:51:30 Gene Heskett wrote:

Update, having fixed the funkity cable. I went to work on my 
holefinder.ngc code, and it is now giving me plus or minus .0001 
repeatable results. I can live with that. :)  Now, if I can get the sim 
version of lcnc to reload the mill config, I'll be off the races, 
writing the code to finish the flange sides of these bellows nipples.

Sounds like a good project for tomorrow morning since I just put another 
half a mile on these legs at the grocery store, and they are 
complaining.

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] pressure equalizer method around ball nut

[Gene Heskett]

On Friday 07 October 2016 19:05:56 Gene Heskett wrote:

> Greetings to PCW;
>
> I have a 2nd apparent failure of a 5i25, affecting the same p3-15 pin.
> So I am suspecting I have a bad BoB or home rolled cable.
>
> I have a perfectly good 4.77 volts at the BoB's input, which does go
> to ground if I touch the wire to the machine frame, but it is not
> getting thru the BoB and the 5i25 to motion.probe-input.
>
> How hard is it to setup a 3rd port, using the parport in the computer,
> so I could move the cable to the parport long enough to verify it is,
> or isn't, the 5i25.
>
> Unlike the first time when I thought I had blown that pin on the 5i25
> because there wasn't a solid ground on the machine frame, this time
> there is zero volts dc on the machine frame, and less than 1 millivolt
> of AC with the motors all moving, So I do have a good ground now.  And
> I have cable and connectors enough to make a new cable.  And I've
> another BoB because I bought two for the Sheldon.  So somewhere in
> this briarpatch is a fix. Changing the BoB would be a PIMA because
> while the old on is pretty much straight thru, the 2 new ones I have
> are hopelessly scrambled.
>
> Is that parport tester in the docs standalone?  If yes, that should
> sort this quite a bit faster. Just move the cable to the parport and
> test away.
>
> Things to check other than what I just listed?
>
> That teflon rod, with a piece of 10 gauge copper for the probe is
> together and looks like it will work well with my hole finder routine.
>
> But first I need to actually make a G38.2 work.
>
> Thanks Peter.
>
> Cheers, Gene Heskett

I think I found it. I put another cable and bob on that 5i25 socket, 
worked. Looking at the male to male I had to use with that hacked up 
BOB, I could see it was 10 or 15 thou from being fully crimped, so 
another few pinches with the vice and it seems to have a solid 
connection now. I suspect there is nothing wrong with the 5i25 I took 
out from the first time it failed. So back to the grindstone with this 
current project. I don't really like that particular male IDC, it did 
not come with the cable clamping top.

Thanks all for bearing with me.

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] pressure equalizer method around ball nut

[Gene Heskett]

On Saturday 08 October 2016 01:23:06 Gregg Eshelman wrote:

> Pretty simple. There's a vertical dial indicator on top, which doesn't
> rotate. The rods fit into the bottom part that does rotate. If the ID
> or OD it's touching isn't precisely centered, the rod wiggles back and
> forth, causing another part to move up and down as the rod spins
> around. Sort of like the reverse of collective pitch control in a
> helicopter. When the needle on the indicator stops wiggling, the part
> is centered under the spindle.
>
Sounds like a handy gizmo to have, and easy enough for the all mechanical 
types to understand.  But a shop made electrical probe and some g38.2 
magic works for that to a fraction of a thou repeatability, and it 
didn't cost me anything, and might be faster. But probably 6 of one, a 
half dozen of the other time wise.  As a C.E.T., I naturally lean to the 
all electrical solution and some gcode to do that as its free of any $ 
expenditure. :)
>
>
>   From: Gene Heskett <ghesk...@shentel.net>
>  To: emc-users@lists.sourceforge.net
>  Sent: Friday, October 7, 2016 8:47 AM
>  Subject: Re: [Emc-users] pressure equalizer method around ball nut
>
> On Friday 07 October 2016 09:46:22 andy pugh wrote:
> > You could consider using one of these instead of a probe:
> > http://www.ebay.com/itm/CO-AX-INDICATOR-MILLING-MACHINE-COAXIAL-COAX
> >-0 005-/300841418164
>
> I've not figured out how one of those works.  The price seems decent
> though.
>
>
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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] pressure equalizer method around ball nut

[Gene Heskett]

On Saturday 08 October 2016 01:10:47 Gregg Eshelman wrote:

> Or you could get a coaxial indicator like
> this.http://www.ebay.com/itm/262647994320
>
Maybe, but I've used a G38.2 wrapper to do this function several thousand 
times.  So my efforts to find why its not now getting to the 5i25's 
gpio.003.in_not from pin 15 on the bob will continue, starting with a 
good cable shake (its a shop made cable based on idc connectors on both 
ends) once I get up on the ladder to reach it comfortably later this 
morning.

This is all up on a sturdy shelf about 6 feet up in the air. And I've got 
another 80 feet of the cable and bags of those idc connectors.

I was too tired to continue any farther as I had been on my feet, 
standing in front of TLM all day, carving the flanges and center thru 
holes on the makings of 4 of these bellows nipples, when I found the the 
contact was getting to the bob's pin 15 but not showing at 
hm2_5i25.0.gpio.003.in_not on a halmeter.

That leaves the bob, the cable, and the 5i25, which has been replaced 
once already to fix this same problem early last spring.  That narrows 
the area to search. I have another bob too, but its a PITA because its 
IO is labeled for use with mach and its a chore to trace thru the docs 
and find the io pins by pin number.

There are several ways to skin this cat, I just need to expend the 
giddyup to do it. :)

Thanks Gregg.

>   From: Gene Heskett <ghesk...@shentel.net>
>  To: emc-users@lists.sourceforge.net
>  Sent: Friday, October 7, 2016 7:33 AM
>  Subject: Re: [Emc-users] pressure equalizer method around ball nut
>
> Film at 11, but day unknown. :) When I get the other two thru holes
> bored, I think next is an insulated probe so I can find the exact
> center of the thru holes on the mill. Thats something I've yet to
> cobble up. Squeeze a piece of 12ga solid copper in a couple layers of
> heat shrink in the drill chuck, split the end of a stranded wire &
> wrap it around the solid wire for the G38.2 probe connection, bending
> the end of the 12 gage solid so it, when spinning at a couple hundred
> rpms, fits in the hole & the machine doesn't have to move all that far
> to find all four "corners" of the hole, from which the exact center,
> well within a thou, can be found.
>
>
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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] pressure equalizer method around ball nut

[Gregg Eshelman]

Galvanic corrosion from different metals in contact with any amount of 
moisture. Running electricity through the contact makes it worse.
The only way aluminum wiring meets code is with a copper pigtail between it and 
any screwed down or push in connection. There are special crimp sleeves and 
tools to compress the aluminum and copper very tightly together, breaking the 
oxide film on the aluminum wire and sealing out oxygen and moisture so it 
doesn't oxidize again.
Most of the aluminum wire in homes got installed during a time when it was a 
lot cheaper than copper. Then breaker boxes, plugins and light switches began 
to set houses on fire.


 
  From: Dave Cole <linuxcncro...@gmail.com>
 To: emc-users@lists.sourceforge.net 
 Sent: Friday, October 7, 2016 10:09 AM
 Subject: Re: [Emc-users] pressure equalizer method around ball nut
   
Next question;  Why do aluminum electrical connections tend to melt down 
sometimes??  I've experienced several aluminum wire to terminal 
failures...  However most of them were made without the mandatory 
anti-corrosive paste.

Dave
   
 
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Re: [Emc-users] pressure equalizer method around ball nut

[Gregg Eshelman]

Pretty simple. There's a vertical dial indicator on top, which doesn't rotate. 
The rods fit into the bottom part that does rotate. If the ID or OD it's 
touching isn't precisely centered, the rod wiggles back and forth, causing 
another part to move up and down as the rod spins around.
Sort of like the reverse of collective pitch control in a helicopter.
When the needle on the indicator stops wiggling, the part is centered under the 
spindle.



 
  From: Gene Heskett <ghesk...@shentel.net>
 To: emc-users@lists.sourceforge.net 
 Sent: Friday, October 7, 2016 8:47 AM
 Subject: Re: [Emc-users] pressure equalizer method around ball nut
   
On Friday 07 October 2016 09:46:22 andy pugh wrote:

> You could consider using one of these instead of a probe:
> http://www.ebay.com/itm/CO-AX-INDICATOR-MILLING-MACHINE-COAXIAL-COAX-0
>005-/300841418164

I've not figured out how one of those works.  The price seems decent 
though.
   
 
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Re: [Emc-users] pressure equalizer method around ball nut

[Gregg Eshelman]

Or you could get a coaxial indicator like 
this.http://www.ebay.com/itm/262647994320


 
  From: Gene Heskett <ghesk...@shentel.net>
 To: emc-users@lists.sourceforge.net 
 Sent: Friday, October 7, 2016 7:33 AM
 Subject: Re: [Emc-users] pressure equalizer method around ball nut
   
Film at 11, but day unknown. :) When I get the other two thru holes 
bored, I think next is an insulated probe so I can find the exact center 
of the thru holes on the mill. Thats something I've yet to cobble up. 
Squeeze a piece of 12ga solid copper in a couple layers of heat shrink 
in the drill chuck, split the end of a stranded wire & wrap it around 
the solid wire for the G38.2 probe connection, bending the end of the 12 
gage solid so it, when spinning at a couple hundred rpms, fits in the 
hole & the machine doesn't have to move all that far to find all 
four "corners" of the hole, from which the exact center, well within a 
thou, can be found.
   
 
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Re: [Emc-users] pressure equalizer method around ball nut

[Gene Heskett]

Greetings to PCW;

I have a 2nd apparent failure of a 5i25, affecting the same p3-15 pin.  
So I am suspecting I have a bad BoB or home rolled cable.

I have a perfectly good 4.77 volts at the BoB's input, which does go to 
ground if I touch the wire to the machine frame, but it is not getting 
thru the BoB and the 5i25 to motion.probe-input.

How hard is it to setup a 3rd port, using the parport in the computer, so 
I could move the cable to the parport long enough to verify it is, or 
isn't, the 5i25.

Unlike the first time when I thought I had blown that pin on the 5i25 
because there wasn't a solid ground on the machine frame, this time 
there is zero volts dc on the machine frame, and less than 1 millivolt 
of AC with the motors all moving, So I do have a good ground now.  And I 
have cable and connectors enough to make a new cable.  And I've another 
BoB because I bought two for the Sheldon.  So somewhere in this 
briarpatch is a fix. Changing the BoB would be a PIMA because while the 
old on is pretty much straight thru, the 2 new ones I have are 
hopelessly scrambled.

Is that parport tester in the docs standalone?  If yes, that should sort 
this quite a bit faster. Just move the cable to the parport and test 
away.

Things to check other than what I just listed?

That teflon rod, with a piece of 10 gauge copper for the probe is 
together and looks like it will work well with my hole finder routine.  

But first I need to actually make a G38.2 work.

Thanks Peter.

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] pressure equalizer method around ball nut

[andy pugh]

On 7 October 2016 at 20:55, Przemek Klosowski
 wrote:
> If the alumina layer is thickened (e.g. by anodization), the aluminum
> objects will be isolated;

I will also note the apparent conductivity of my anodized
solder-sucker. But that is probably a think anodised layer, not one
intended for isolation.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] pressure equalizer method around ball nut

[Przemek Klosowski]

On Fri, Oct 7, 2016 at 1:08 PM, andy pugh  wrote:

> On 7 October 2016 at 17:09, Dave Cole  wrote:
> >
> > Does this give me a clue?
> > https://www.researchgate.net/post/What_is_aluminium_and_
> its_oxide_electrical_properties2
>
> It seems to be lots of people saying "Aluminium is non-conducting"
> without doing the simple test with a multimeter to check their theory.
>

Aluminum metal is of course conductive, because it is, well, a metal with
free charge carriers and all. Al2O3 (aka ALUMINA)  layer on the surface is
not conductive, except that when it is naturally formed, it's just 5-10nm
thick. If you apply 1V across it, the field strength is in the megavolts
per centimetre, which happens to be near the dielectric breakdown field for
alumina, so under normal conditions you get conductivity.

If the alumina layer is thickened (e.g. by anodization), the aluminum
objects will be isolated; this is sometimes used for heatsinks and such,
except that the isolation is fragile because alumina is hard, and the
underlying aluminum metal is soft.
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Re: [Emc-users] pressure equalizer method around ball nut

[andy pugh]

On 7 October 2016 at 20:08, Gene Heskett  wrote:
> Force one probe to actually dent the surface so you know you are making a
> connection WITH that probe. Then lay, or let gently swing to touch a
> clean looking spot, the other probe, without using the point, or a sharp
> edge on the test aluminum and the gentlest touch you can manage. Your
> digital volt/ohm meter, which likely doesn't use more than its internal
> battery voltage, 9 volts max, shouldn't be able to detect a connection.
> You will not get a connection until you have applied enough force to
> crush/penetrate that oxide film, which if its fresh, as in a 1 hour old
> machined surface might be 10 atoms thick, but its still growing thicker,
> maybe 100 atoms thick 2 weeks later.  Thats good for around 400 volts

Have you actually tried to prove this theory of yours?

I just did. On a bit of aluminium sheet that was lying on my desk,
which, until it fatigued through, had been the bracket for the light
on my bicycle.

You might think that theory trumps experiment, but I disagree. Maybe
thats why they paid me to do experiments in metallurgy for all those
years?

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] pressure equalizer method around ball nut

[Gene Heskett]

On Friday 07 October 2016 12:09:35 Dave Cole wrote:

> On 10/7/2016 11:48 AM, andy pugh wrote:
> > On 7 October 2016 at 15:47, Gene Heskett  
wrote:
> >>> I have never found aluminium to be non-conductive.
> >>
> >> Its a good conductor, IF you can achieve a 'gas tight' connection,
> >> AND maintain it for decades.
> >
> > No, really. Get some aluminium and your multimeter. You will find
> > that it conducts.
>
> OK... I'll bite.
>
> Why does it conduct if there is an insulating coating of Alox on the
> surface??
>
> Does this give me a clue?
> https://www.researchgate.net/post/What_is_aluminium_and_its_oxide_elec
>trical_properties2
>
> It mentions tunneling.  Sounds like a semi conductor property.
>
> Next question;  Why do aluminum electrical connections tend to melt
> down sometimes??   I've experienced several aluminum wire to terminal
> failures...  However most of them were made without the mandatory
> anti-corrosive paste.
>
> Dave
>
You have found the answer Dave. Alu wire, to me, is a lot like concrete, 
because folks ask if it will crack, or sometimes if the wire will start 
a fire.  The answer to both is 100% yes, and people who ask if it "will" 
crack, should be asking "when", not if, because cement will crack, and 
alu wire "will" start a fire. Cracking cement has not tried to kill me 
yet, alu wire has made 2 passes at it over the last 50 years.  I don't 
like those odds.

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] pressure equalizer method around ball nut

[Gene Heskett]

On Friday 07 October 2016 11:48:07 andy pugh wrote:

> On 7 October 2016 at 15:47, Gene Heskett  wrote:
> >> I have never found aluminium to be non-conductive.
> >
> > Its a good conductor, IF you can achieve a 'gas tight' connection,
> > AND maintain it for decades.
>
> No, really. Get some aluminium and your multimeter. You will find that
> it conducts.

Force one probe to actually dent the surface so you know you are making a 
connection WITH that probe. Then lay, or let gently swing to touch a 
clean looking spot, the other probe, without using the point, or a sharp 
edge on the test aluminum and the gentlest touch you can manage. Your 
digital volt/ohm meter, which likely doesn't use more than its internal 
battery voltage, 9 volts max, shouldn't be able to detect a connection.  
You will not get a connection until you have applied enough force to 
crush/penetrate that oxide film, which if its fresh, as in a 1 hour old 
machined surface might be 10 atoms thick, but its still growing thicker, 
maybe 100 atoms thick 2 weeks later.  Thats good for around 400 volts 
before a single electron can penetrate it by a microscopic arcing.  Its 
also the near top of the list of electrical insulators, I think only the 
silicone dioxide used as the gate insulation layer in a field 
(mosfet,hexfet) effect transistor is above it.  That 1 hour old machined 
surface is still rough enough, and that roughness concentrates your test 
force to the tip tops of that roughness, so relatively little force will 
make contact as the oxide film is now mechanically damaged.  Arrange to 
leave the probe laying there for a few hours. Because air can get under 
the probe, the damage will be repaired, and the connection will 
disappear unless sufficient force is applied, and stays applied so that 
the oxygen in the air is forced out of the contact and cannot over time 
degrade it.  This is then a "gas tight" connection, and many millions 
have been spent designing an electrical box screw the top bolt in to 
grip the joint and make a good connection today, and because it has the 
right springiness, is still applying enough pressure years later to 
maintain that gas tight joint in a gas tight category.

Its a very elusive target, and the electrical people are told to cover 
the end of the wire with a grease called no-ox before they stick it into 
the terminal and tighten the screw. I've seen union electricians that 
had a tube of it in the kit, maybe 8 oz ten years ago, still has 6 oz in 
it a decade later. I'd encourage them to find another line of work. They 
are a long term liability on the jobsite.  OTOH, I've seen them stop 
work and go get another tube of it when they run out.

Its job is to seal the air out of a joint, thereby preventing this 
failure. In many locales it is illegal to use alu wire without this 
grease. In the stricter locales, alu wire is illegal if the building is 
a dwelling.

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] pressure equalizer method around ball nut

[andy pugh]

On 7 October 2016 at 17:09, Dave Cole  wrote:
>
> Does this give me a clue?
> https://www.researchgate.net/post/What_is_aluminium_and_its_oxide_electrical_properties2

It seems to be lots of people saying "Aluminium is non-conducting"
without doing the simple test with a multimeter to check their theory.

Gene: You will be able to probe for aluminium with no difficulty at
all. Furthermore, carbide conducts too, (again, a multimeter will
prove this)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] pressure equalizer method around ball nut

[Dave Cole]

On 10/7/2016 11:48 AM, andy pugh wrote:
> On 7 October 2016 at 15:47, Gene Heskett  wrote:
>>> I have never found aluminium to be non-conductive.
>>>
>> Its a good conductor, IF you can achieve a 'gas tight' connection, AND
>> maintain it for decades.
> No, really. Get some aluminium and your multimeter. You will find that
> it conducts.

OK... I'll bite.

Why does it conduct if there is an insulating coating of Alox on the 
surface??

Does this give me a clue?
https://www.researchgate.net/post/What_is_aluminium_and_its_oxide_electrical_properties2

It mentions tunneling.  Sounds like a semi conductor property.

Next question;  Why do aluminum electrical connections tend to melt down 
sometimes??   I've experienced several aluminum wire to terminal 
failures...  However most of them were made without the mandatory 
anti-corrosive paste.

Dave




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Re: [Emc-users] pressure equalizer method around ball nut

[andy pugh]

On 7 October 2016 at 15:47, Gene Heskett  wrote:
>> I have never found aluminium to be non-conductive.
>>
> Its a good conductor, IF you can achieve a 'gas tight' connection, AND
> maintain it for decades.

No, really. Get some aluminium and your multimeter. You will find that
it conducts.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
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Re: [Emc-users] pressure equalizer method around ball nut

[Gene Heskett]

On Friday 07 October 2016 10:34:19 Roland Jollivet wrote:

> On 6 October 2016 at 17:27, Gene Heskett  wrote:
> > On Thursday 06 October 2016 09:54:59 andy pugh wrote:
> > > On 6 October 2016 at 12:32, Gene Heskett  
wrote:
> > > > Anybody got a better idea than sacrificing two of the six bolt
> > > > positions to make the coupling vents?
> > >
> > > Tubular bolts?
> > >
> > > Oh, you said _better_ ideas?
> >
> > Or even drilling a random but bigger hole but that would involve
> > removal of the nut, catching all the balls and then feed them back
> > into the nut. I think I'll pass as these nuts do not have removable
> > return tubes. But that doesn't prevent me from boring the thru-hole
> > at least the same size
>
> Hi Gene
>
> You don't need to remove the balls. Just find some hose that matches
> the min OD of the ballscrew, probably around 22mm. Then you just roll
> the nut onto the hose. Carefully..
>
> Also, if you have shop air available at the machine, you could add
> 1/8th fittings to either end of the bellows, or at the nut, and piss a
> teeny amount of air into each end of the bellows. A low pressure
> regulator or just a restrictor would work. A positive pressure on both
> sides of the nut will mean;
> - no equilibrium needed
> - will always be purged with clean air
> - dispense with a vacuum being generated on one side during travel
> which can suck dust in.
>
Agreed Roland. The devil is in the details of course. :)

Thanks Roland.

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] pressure equalizer method around ball nut

[Gene Heskett]

On Friday 07 October 2016 09:46:22 andy pugh wrote:

> On 7 October 2016 at 14:33, Gene Heskett  wrote:
> >   It all gets complex fast when dealing with alu and
> > its instant oxidation.
>
> I have never found aluminium to be non-conductive.
>
Its a good conductor, IF you can achieve a 'gas tight' connection, AND 
maintain it for decades.  But because of cold flow when dis-similar 
temps expansions are encountered, the average life of a crimp sleeve 
connecting your houses copper sticking out of the weatherhead, to the 
alu cable from the transformer on that pole across the street, is, IF 
the crimp is well done, perhaps 30 years.  When I am on my roof for any 
reason, one of the things I always do is walk over and feel those 
crimped connections for heat buildup. Here, they are only 8 years old, 
but before that drop line was replaced because I had replaced a 60 amp 
service with a 200 in 2008, 2 of the 3 original connections made up in 
1974 had already failed, one burning completely in two in about 1997. 

I have also had the  nominally 7" long aluminum jumpers from the meter 
socket, thru the wall to the service in a closet on the other side of 
that wall, try to burn my house down in the middle of a -15F Nebraska 
night in February, with the buzzing of the arc in the closet waking me 
up.  That was the 2nd time that alu wire had tried to burn me out.

I will not knowingly buy a structure with aluminum wire under the roof. I 
cut the seal on the meter and fixed it with some copper that wasn't 
heavy enough, but then went to the transmitter and "borrowed" about 8" 
of 6 gage copper to fix it right the next day.  Cutting the meter seal 
is a felony in most locales, and its probably a good thing that I knew 
the head lineman at the power company, because when I called him to send 
somebody by and put a new seal on the meter, he had to have a good 
explanation as to why I cut it.  The tv station, kxne, was a uhf, and 
was their highest billing customer at about 225 kw load during operating 
hours. Klystron amplifiers are hungry beasts.

Alu, cut into with our cutting tools, oxidizes so rapidly behind the edge 
of the tool, that in .001 second, the film has achieved a 50 volt 
withstand. To make a connection, you must touch it with enough force to 
penetrate that oxide film.  Since alox is the 2nd hardest substance we 
know about, its cutting dulls our tools much faster than when cutting 
other non-ferrous materials.

> You could consider using one of these instead of a probe:
> http://www.ebay.com/itm/CO-AX-INDICATOR-MILLING-MACHINE-COAXIAL-COAX-0
>005-/300841418164

I've not figured out how one of those works.  The price seems decent 
though.

> Thought, actually, with a bit of neck-craning and possibly the use of
> a mirror you can centre a mill-spindle to a bore or round stock with a
> generic indicator and an improvised mount.

Thanks Andy.

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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[Emc-users] pressure equalizer method around ball nut

[Roland Jollivet]

On 6 October 2016 at 17:27, Gene Heskett  wrote:

> On Thursday 06 October 2016 09:54:59 andy pugh wrote:
>
> > On 6 October 2016 at 12:32, Gene Heskett  wrote:
> > > Anybody got a better idea than sacrificing two of the six bolt
> > > positions to make the coupling vents?
> >
> > Tubular bolts?
> >
> > Oh, you said _better_ ideas?
>
> Or even drilling a random but bigger hole but that would involve removal
> of the nut, catching all the balls and then feed them back into the nut.
> I think I'll pass as these nuts do not have removable return tubes. But
> that doesn't prevent me from boring the thru-hole at least the same size
>

Hi Gene

You don't need to remove the balls. Just find some hose that matches the
min OD of the ballscrew, probably around 22mm. Then you just roll the nut
onto the hose. Carefully..

Also, if you have shop air available at the machine, you could add 1/8th
fittings to either end of the bellows, or at the nut, and piss a teeny
amount of air into each end of the bellows. A low pressure regulator or
just a restrictor would work. A positive pressure on both sides of the nut
will mean;
- no equilibrium needed
- will always be purged with clean air
- dispense with a vacuum being generated on one side during travel which
can suck dust in.

Regards
Roland
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Re: [Emc-users] pressure equalizer method around ball nut

[andy pugh]

On 7 October 2016 at 14:33, Gene Heskett  wrote:
>   It all gets complex fast when dealing with alu and
> its instant oxidation.

I have never found aluminium to be non-conductive.

You could consider using one of these instead of a probe:
http://www.ebay.com/itm/CO-AX-INDICATOR-MILLING-MACHINE-COAXIAL-COAX-0005-/300841418164

Thought, actually, with a bit of neck-craning and possibly the use of
a mirror you can centre a mill-spindle to a bore or round stock with a
generic indicator and an improvised mount.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] pressure equalizer method around ball nut

[Gene Heskett]

On Thursday 06 October 2016 11:27:46 Gene Heskett wrote:

> On Thursday 06 October 2016 09:54:59 andy pugh wrote:
> > On 6 October 2016 at 12:32, Gene Heskett  
wrote:
> > > Anybody got a better idea than sacrificing two of the six bolt
> > > positions to make the coupling vents?

I made some progress yesterday. Turned out the alu rod I had wasn't thick 
enough, so I sawed up a 2" thick block of 7075-T6. I've the flange 
turned on all 4, and the center thru hole for the 2505 screw on 2 when 
my feet said it was quitting time. I did make at least a pound of swarf, 
but there's going to be a lot more.  The first piece of the round rod 
will serve as a plug gage as its 35mm OD is exactly the size of the 
bellows.

I need to scour the net and find a copy of that bolt pattern at some 
point to see if I can apply that to drilling and tapping the bearing 
carriers so two of these can be bolted to the face of the carriers.  
Seems to me two of those 5mm bolts pulling it against the block face 
after drawing a line of GO-2 on it for sealant should be plenty sturdy 
enough.

Film at 11, but day unknown. :) When I get the other two thru holes 
bored, I think next is an insulated probe so I can find the exact center 
of the thru holes on the mill. Thats something I've yet to cobble up. 
Squeeze a piece of 12ga solid copper in a couple layers of heat shrink 
in the drill chuck, split the end of a stranded wire & wrap it around 
the solid wire for the G38.2 probe connection, bending the end of the 12 
gage solid so it, when spinning at a couple hundred rpms, fits in the 
hole & the machine doesn't have to move all that far to find all 
four "corners" of the hole, from which the exact center, well within a 
thou, can be found.

I've also some teflon that could be used to hold the probe wire. Biggest 
problem there is how do I lock the probing wire into the teflon? I don't 
think I have a glue that works for teflon. Set screw maybe?  We'll have 
to play with that idea.  Poor mans Reneshaw. Accuracy determined by how 
long the end of the wire has to touch and slide along, polishing the end 
of the wire to a mirror finish before it cuts thru the alox surface 
insulation and registers.

Ideally there would be a 500 volt probe voltage so it would penetrate the 
alox easily even a month later.  Current limited so as not to damage the 
workpiece, perhaps 10 micro-amps?  Nice idea, but I don't have such a 
static electricity generator.  That would also need an isolation diode 
between this high voltage and the 5i25's logic input, and possibly even 
a 2nd diode to the supply rail to absorb the junction charge of the 
protection diode.  It all gets complex fast when dealing with alu and 
its instant oxidation.  I'll sort something out though. Sigh, $%#@ time 
sinks.

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] pressure equalizer method around ball nut

[Gene Heskett]

On Thursday 06 October 2016 22:20:36 Gregg Eshelman wrote:

> On the steering racks Ford used on the Pinto and Mustang II, the big
> ends of the bellows/boots had the ID off center with a vent hole for a
> metal pipe (around 1/4" ID) to push in so that air could flow back and
> forth as the rack moved. Whatever you do, it shouldn't require a
> really large vent to allow air to flow back and forth.

Having at one time owned a Pinto. I recall that, and wondered at the time 
how they ever expected to keep it clean internally in the face of 
everything that flew up off the tires in wet or dirty weather.

I have some satellite jack boots in a drawer in the shop building that 
have a vent/drain in one end of them.  You've got a motor with stripped 
and broken gears if such a jack is installed horizontally so it can't 
drain, because then it all runs into the motor and the 3rd good freeze 
breaks it completely, even busting the gearcase open once.  That same 
jack & motor is happy as a clam for decades with the same jack is used 
for elevation at a nominally 45 degree angle, motor down. I once, while 
at WDTV, and RCA had filed, which made the 3.9 meter AFC dish they gave 
us open for other uses, so I hit the iron pile and made a 1/2 sized 
version of the Scientific Atlanta 7 meter dish, putting the azimuth 
motor horizontal just like SA mounted the monster Roland jacks they 
used. Worked really well on that AFC dishbecause that dish was a genuine 
1 minute rifle barrel.  Until about march of the next spring and I got a 
frantic call from one of the studio techs saying it wasn't working.  By 
the time I got there it had warmed up so the ice was all melted, leaving 
perhaps a teaspoon in the gearbox which was full of busted nylon. No one 
in town had another jack motor, nor a jack that long as it was a 6 
footer.  Nothing else to do but get a check cut and point the stations 
pickup at Venture Mfg, in the industrial park NW of the Dayton, OH 
Airport. Long days drive and I put the new one on in the dark and 
recalibrated the controller before I pointed the truck south to Weston 
WV, something after midnight.

I bitched and belly ached until I had permission to order a spare because 
I knew I was going to need it. And of course I did, several more times 
before I retired.  By now its probably in its 2nd dozen 'spare' 
jacks. :)  Nothing seems to help for good, including a 3/8" drain hole 
in the bottom of the gearbox might make it last 2 winters. The dishes 
pivot joints are Chevy truck ball joints, greased at least annually, 2 
pounds on the lever which is more than 4 feet long moves the dish 
easily.  Wind load is not that much off-center as I've replaced that 
jack in a 40 mph breeze without any difficulty holding it steady enough 
to re-install the connector bolt.

Pinto made it work, somehow.  The exception to the good, cheap, runs 
forever rule I guess.

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] pressure equalizer method around ball nut

[Gregg Eshelman]

On the steering racks Ford used on the Pinto and Mustang II, the big ends of 
the bellows/boots had the ID off center with a vent hole for a metal pipe 
(around 1/4" ID) to push in so that air could flow back and forth as the rack 
moved.
Whatever you do, it shouldn't require a really large vent to allow air to flow 
back and forth.
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Re: [Emc-users] pressure equalizer method around ball nut

[Gene Heskett]

On Thursday 06 October 2016 09:54:59 andy pugh wrote:

> On 6 October 2016 at 12:32, Gene Heskett  wrote:
> > Anybody got a better idea than sacrificing two of the six bolt
> > positions to make the coupling vents?
>
> Tubular bolts?
>
> Oh, you said _better_ ideas?

Or even drilling a random but bigger hole but that would involve removal 
of the nut, catching all the balls and then feed them back into the nut. 
I think I'll pass as these nuts do not have removable return tubes. But 
that doesn't prevent me from boring the thru-hole at least the same size 
as the bolt hole in the nut flange.  So I'll make the flanges on the two 
used at the nut about 3/8" thick, and plow a groove about a quarter in 
deep from the inner diameter out to cover the drilled thru holes.  The 
bigger the better as I'd druther not have the air moving thru it at air 
nozzle violence.  The idea just crossed my mind too, to put some sort of 
a fitting in the end nipples, that would allow a slightly positive air 
pressure to be established as a further reduction in sucked in dirt.

Once what I am thinking is done, I can always spin it with a hand drill 
so I can see any flow restriction effects from G0 movements. A 1 lb over 
PSIA internal pressure, if maintainable, would go a long ways toward 
preventing a vacuum collapse of the bellows being stretched.  Enough 
pressure to make them rigid enough that they won't sag into contact with 
the screws would be a plus in my mind  I have shop air of course but no 
handy regulators that could do 1 lb reliably.  

Darn, you get the nuttiest ideas out of me when I let my mind out to 
play. :)

Thanks Andy.

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] pressure equalizer method around ball nut

[andy pugh]

On 6 October 2016 at 12:32, Gene Heskett  wrote:
> Anybody got a better idea than sacrificing two of the six bolt positions
> to make the coupling vents?

Tubular bolts?

Oh, you said _better_ ideas?

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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[Emc-users] pressure equalizer method around ball nut

[Gene Heskett]

Greetings all;

I am about at that stage in this conversion where I am about to hang the 
Z screw.  I have some bellows to serve as debris shields around the 
screw.  So I'll need to make "nipples" to connect the bellows, at the 
support bearings and at the traveler nut mount.  Alu rod enough for that 
I have.

But the bellows need venting somehow, and it seems to me the best way is 
to rig an air bypass around the nut so its effectively a sealed, 
constant volume system with no swarf ingress.  The nut carrier is not 
drilled thru at any of the nut mounting holes but it seems to me the 
best way would be to drill the center hole in each 3 bolt pattern clear 
thru the carrier, putting mount bolts in only 4 of the 6 positions of 
the bolt pattern, and make the nipples on the nut with a carved passage 
from the center that reaches the thru hole, thereby giving moderately 
free air flow around the nut by way of the 2 empty boltholes while 
maintaining a near constant volume inside the bellows.  That it seems 
would discourage to a large degree, any chance of sucking in swarf or 
other dirt to shorten the life of the ball screw. The other end of the 
nut carrier will be drilled and tapped for small bolts to retain these 
nipples.

The end bearing supports will also need drilled & tapped to mount the 
nipples on the end's of the screw, but that can be just a flush mount, 2 
bolts, sealed to the bearing bracket with some sili-seal.

It should be more free flowing than trying to find room for some 1/8" 
pipe to hose barb fittings and bypassing with plastic tubing.

Anybody got a better idea than sacrificing two of the six bolt positions 
to make the coupling vents?

Thank you all for any guidance.

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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