Re: [Emc-users] Soft starting my mills spindle supply

[Jon Elson]

On 12/12/2015 08:32 PM, Gene Heskett wrote:
>
> As I'd druther not have to listen to those contactors humm & buzz when
> powered by 120 AC, my thoughts are to use that transformer as a step
> down, feeding the nominally (I haven't measured it yet) into a bridge,
> feeding the contactor coils with somewhat filtered DC from that, which
> ought to silence them.
>
> But I suspect that 90 volts (cap input filter) is still way too much for
> those coils over any time period in excess of 2 or 3 minutes.
>
> So, how much more do I need to reduce the coil voltage in order to run
> them at a reasonable temperature on DC?
>
>
This won't work.  AC contactors depend on the change in 
inductance when the armature slams home into the stator.  
So, they pull a lot of current when in the un-energized 
position, and then the current drops drastically when 
pulled-in.  The only way to do this is to have an NC contact 
that delivers full current to the coil until it is pulled 
in, then opens to put a resistor in series with the coil.

Jon

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Re: [Emc-users] Soft starting my mills spindle supply

[Erik Christiansen]

On 12.12.15 21:32, Gene Heskett wrote:
> But I suspect that 90 volts (cap input filter) is still way too much for 
> those coils over any time period in excess of 2 or 3 minutes.
> 
> So, how much more do I need to reduce the coil voltage in order to run 
> them at a reasonable temperature on DC?
> 
> I have some other toroid trannies that might be more suited for this as I 
> suspect the operation from DC can probably be reliably done with 30 
> volts w/o baking the coils.
> 
> Does anyone else have similar experience who can toss a few words my way 
> on this?

They might hold on 30v, but I don't see them pulling in on it. If the
relay is switched well after power-up, then a resistor feed of DC to a
middle-sized electrolytic briefly provides full pull-in voltage via
whatever switches the coil current, and the resistor is scaled for
coolness, according to taste. (Well, finger-burn, actually.)

Now, to "unsimplicate", if that is the builder's bent, there are gadgets
like: http://www.ti.com/lit/ds/symlink/drv120.pdf , located by a quick
google for "pwm solenoid relay driver". 

There are doubtless other ways to cook this cat, variously attractive,
depending on ingredients to hand.

Erik

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Re: [Emc-users] Z axis stepper gradually losing position

[John Alexander Stewart]

I had X issues - observable on a long job of engraving. Job came out
slightly not square!

5I25 to a Gecko G540 - as mentioned above, inverting the polarity of the
signal(s) fixed it - I was pushing the Gecko G540 slightly too fast. Only
one input of the XYZA showed the symptom.

The machine has been rock stable since.

I'd have to go through my backup files and/or notes to see exactly what
signal was inverted.

May I suggest doubling pulse lengths, and seeing if that helps? Give the
drivers time to settle into a known state?

Good luck - John.

On Fri, Dec 11, 2015 at 8:47 PM, Gene Heskett  wrote:

> On Friday 11 December 2015 18:21:20 andy pugh wrote:
>
> > On 11 December 2015 at 22:41, Marcus Bowman
> >
> >  wrote:
> > > The tiniest error in your (software) backlash settings accumulate
> >
> > If it does, that's a bug.
> >
> > It is more likely to be that the backlash comp moves are at max speed.
> > If max speed is over-optimistic, then that can case problems.
>
> Does that not depend on the Linuxcnc version? I haven't heard it trying
> to do a backlash move at knock it out of the park speeds in quite a
> while.  I had assumed (there's that word again) that a backlash move was
> now being made not only subject to the max vel, but also, subject to the
> max-accel settings which it didn't do 2-3 years ago.
>
> Or am I dreaming?  ChangeLogs readable by us dummies might be helpful?
>
>
> 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)
> Some mill pix are at:
> Genes Web page 
>
>
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Re: [Emc-users] Z axis stepper gradually losing position

[Peter C. Wallace]

On Sat, 12 Dec 2015, John Alexander Stewart wrote:

> Date: Sat, 12 Dec 2015 13:46:58 -0500
> From: John Alexander Stewart 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: "Enhanced Machine Controller (EMC)" 
> Subject: Re: [Emc-users] Z axis stepper gradually losing position
> 
> I had X issues - observable on a long job of engraving. Job came out
> slightly not square!
>
> 5I25 to a Gecko G540 - as mentioned above, inverting the polarity of the
> signal(s) fixed it - I was pushing the Gecko G540 slightly too fast. Only
> one input of the XYZA showed the symptom.
>
> The machine has been rock stable since.
>
> I'd have to go through my backup files and/or notes to see exactly what
> signal was inverted.
>
> May I suggest doubling pulse lengths, and seeing if that helps? Give the
> drivers time to settle into a known state?
>
> Good luck - John.

If the step pulse is inverted you are likely to violate the direction hold
time

As far as I can tell the G540 timings are based on 5V signals
The 5I25 has 3.3V signals when driving a G540 so timings need to
be relaxed.

You can drive 5V signals with the 5I25 in open drain mode
but only on drives that have differential or common anode
OPTO coupler inputs with the + input(s) tied to 5V


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Re: [Emc-users] Z axis stepper gradually losing position

[Viesturs Lācis]

2015-12-12 21:07 GMT+02:00 Peter C. Wallace :
> If the step pulse is inverted you are likely to violate the direction hold
> time

And that would mean that direction is changed one step later. Which is
fine, because the next direction change would also be done one step
later and thus overall distance of travel still is the same.
How do I invert a step pin in HAL? I did not see anything in "stepgen"
section in hostmot2 doc page. Or is it done by treating it as a gpio
pin with the invert_output parameter (with finding out particular pin
number that corresponds to particular step pin)?

I would like to thank everybody for the ideas, my current to-do list
looks like this:
0) update LinuxCNC to 2.7.something to use new tp (will provide
smoother execution as the g-code consists of small g1 moves);
1) try inverted step pin;
2) recheck steplen, stepspace, dirsetup and dirhold parameters and
increase them, if possible;
3) recheck maxaccel values and do a test with considerably lower values;
4) if the issue is still there - use dial indicator to actually
measure exact error, torture the machine a little more and then post
here again :))

Viesturs

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[Emc-users] Soft starting my mills spindle supply

[Gene Heskett]

Greetings folks;

I have managed to source ancient motor controller box, originally 
intended to serve as a bidirectional motor controller serviced by a 3 
phase circuit.

It has 3, but I'll remove one, 3PST contactors with what from the 
schematic would appear to have 120 volt AC coils.  They measure a bit 
north of 200 ohms.

Also a step-down transformer to deliver 120 for the contactor coils from 
a 220 volt 3 phase feed.  But someone has lifted the transformer out of 
the circuit and rigged it to run the coils from 120volt/ground.  From 
the looks of the input cable,  my guess is that is was simplicated for 
single phase 220 before it was removed from service and scrapped.

As I'd druther not have to listen to those contactors humm & buzz when 
powered by 120 AC, my thoughts are to use that transformer as a step 
down, feeding the nominally (I haven't measured it yet) into a bridge, 
feeding the contactor coils with somewhat filtered DC from that, which 
ought to silence them.

But I suspect that 90 volts (cap input filter) is still way too much for 
those coils over any time period in excess of 2 or 3 minutes.

So, how much more do I need to reduce the coil voltage in order to run 
them at a reasonable temperature on DC?

I have some other toroid trannies that might be more suited for this as I 
suspect the operation from DC can probably be reliably done with 30 
volts w/o baking the coils.

Does anyone else have similar experience who can toss a few words my way 
on this?

Thanks all.

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)
Some mill pix are at:
Genes Web page 

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Re: [Emc-users] Probe

[Jeremy Jones]

https://www.youtube.com/watch?v=AcazGaRj9Xs

Guessing that's the first video. Good video, thanks. I subscribed to your
channel.

On Sat, Dec 12, 2015 at 7:28 PM, Jim Craig 
wrote:

> I use the one from CNC 4 PC. It works pretty good and is relatively
> inexpensive.
>
> I made some videos about using it. They are on the YouTube.
>
> On 12/12/2015 3:20 PM, John Thornton wrote:
> > I could use a probe on my BP Series 1 with Anilam CNC conversion but
> > don't have time to make one. Any suggestions for a US probe?
> >
> > JT
> >
> >
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>
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Re: [Emc-users] Probe

[Jim Craig]

I use the one from CNC 4 PC. It works pretty good and is relatively 
inexpensive.

I made some videos about using it. They are on the YouTube.

On 12/12/2015 3:20 PM, John Thornton wrote:
> I could use a probe on my BP Series 1 with Anilam CNC conversion but
> don't have time to make one. Any suggestions for a US probe?
>
> JT
>
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[Emc-users] Probe

[John Thornton]

I could use a probe on my BP Series 1 with Anilam CNC conversion but 
don't have time to make one. Any suggestions for a US probe?

JT

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