Messages

801

VB and the development of wizards / Re: Macro M6 safety

« on: September 25, 2010, 08:01:05 AM »

Do you have an automatic tool changer and you're afraid it won't work if the tool is stuck? The most right way is to fix the mechanical problem that prevents the tool holder from ejecting from the spindle. Then, if you still feel you need some safety mechanism, you can probably use proximity switches to detect if the tool holder has come out.

More details about your system would help.

Dan

802

Show"N"Tell ( Your Machines) / Re: Just got a lathe to retrofit

« on: September 24, 2010, 09:23:57 AM »

Good work, Hood. Thanks for showing.

Dan

803

FAQs / Re: Losing steps or something?

« on: September 23, 2010, 07:39:54 AM »

Yep

Dan

804

FAQs / Re: Losing steps or something?

« on: September 23, 2010, 07:32:57 AM »

Somehow I can't see this. It might be the case with a DC servo motor, but I think you said you are running large steppers? I am not aware of any significant back emf problems with steppers.

When a stepper motor decelerates large mass from high speed it will act as a current source and send current back to the drive instead of drawing voltage from it. If the power supply voltage is near the drive's max it could damage the drive if proper means of dissipating this energy are not implemented. I was assuming that Don was having some moderate variant of this phenomenon, since the problem was only occurring when two of the motors where moving in the same time.


Dan

805

FAQs / Re: Losing steps or something?

« on: September 23, 2010, 05:40:32 AM »

Yes, Don. Do try rearranging the wires, but still a better thing to try would be to use shielded cables for the motor cables. It's got to be something in the particular way you have it all connected and setup. Lots of people are using exactly the same hardware (and of course software ) with no issues, so it's something in the way you have it all arranged. Power supply doesn't seem to do any difference any more, so do try the wiring.

Dan

806

FAQs / Re: Losing steps or something?

« on: September 23, 2010, 02:37:26 AM »

Problem is that Don has the problem only when two axes are moving simultaneously. When moving each axis separately there is no position lose. That's what makes it strange.

Dan 

807

FAQs / Re: Losing steps or something?

« on: September 22, 2010, 05:13:25 AM »

Hi Don,

It's strange... What's interesting that usually the solution to such problems is a real simple thing. It can also be a combination of several factors and that would really make it hard to detect.

I don't believe it could be it, but we have seen weird things in the past, so just for the sake of it can you uninstall Mach completely and delete its directory including the XMLs. And do a fresh install and set it up from scratch.

Also, what do you have for a step pulse width under motor tuning? Try playing with it. I find that anything above 0 with my G540 doesn't work well. Also try playing with the Step "active low" setting under ports and pins. Also, can you temporarily use a different power supple for the Geckos? Something less than 70VDC. May be up to 60VDC. I still have a feeling it has something to do with the back EMF voltage.

Dan

808

FAQs / Re: Losing steps or something?

« on: September 21, 2010, 07:12:18 AM »

Can you try running the program at a really slow feedrate, something like 1in/min? Does it still lose position? I think it is something related to the back EMF voltage produced by the motor while decelerating. So use a very slow feed rate and also reduce the acceleration. See it if it cures the problem.

You probably didn't have any motion when connected directly from PP to the Gecko drives, since your PP is outputting low voltages (3.3V is common) which is not enough for the drives.

Dan

809

Feature Requests / Re: Motor RPM

« on: September 21, 2010, 03:25:11 AM »

I assume you're wanting this for the axes motors. You could easily do this in a brain or a macropump if you found a way to extract the feedrate of each axis from the blended feed DRO Not so easy I think.

Dan

810

FAQs / Re: Losing steps or something?

« on: September 21, 2010, 03:17:59 AM »

This is a strange one... you're only seeing it when both X and Y are moving...? Is it absolutely repeatable and consistent on both axes? Or it randomly appears on either one of them?

May be the breakout board is under powered? Try using a different power supply with higher current rating.

Dan