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Author Topic: Need HELP Steppers Stalling on Shallow Moves  (Read 11281 times)

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Need HELP Steppers Stalling on Shallow Moves
« on: August 22, 2009, 08:14:31 PM »
OK, ever since I converted my Bridgeport to CNC the X and Y axis lock up when trying to make shallow moves at the same time. So let's say when trying to go from Y0.2 X0.1 to Y8 X.2. I think it's because the machine is trying to move that shallow sliver of a move of X over such a long distance. I noticed it during drilling cycles originally. And before you ask I've tried everything slowing down the motor in motor turning and changing the accerlation down. The motors are more than strong enough 1200 oz. steppers at 150 IPM it can pull me across the floor without missing a step, but even then I tuned them down to 70 IPM as my top speed and of course it still happens.

Some things I noticed months and months ago when trouble shooting it, I readjusted my Y gibs, they were a little loose. I eneded up just forgetting about it and just altering my Gcode to make each move separately until it gets to where it's going. Instead of X2Y2 on one line I would say X2, [new line] Y2, just to be safe. The weird parts is I use this mill all the time doing very complex 3 and 4 axis stuff and it never messes up until I get to shallow moves on a drill cycle; that is until yesterday I was doing some pocketing where there were some extremely shallow moves and it messed up, luckily I was there to Feed Hold and resetup.

Any help would be appreciated. I'm just worried that it's going to mess up somthing real important.
Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #1 on: August 22, 2009, 08:18:19 PM »
How about power supply, is it powerful enough to power all 3 axes at the same time?
Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #2 on: August 22, 2009, 09:29:08 PM »
As I said above I do 3 axis 3D all the time and no problem, the problem is only when doing a shallow X and Y move together. Anyway, I'm using a 72VDC 20AMP power supply.
Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #3 on: August 22, 2009, 11:00:46 PM »
OK, ever since I converted my Bridgeport to CNC the X and Y axis lock up when trying to make shallow moves at the same time. So let's say when trying to go from Y0.2 X0.1 to Y8 X.2. I think it's because the machine is trying to move that shallow sliver of a move of X over such a long distance. I noticed it during drilling cycles originally. And before you ask I've tried everything slowing down the motor in motor turning and changing the accerlation down. The motors are more than strong enough 1200 oz. steppers at 150 IPM it can pull me across the floor without missing a step, but even then I tuned them down to 70 IPM as my top speed and of course it still happens.

Some things I noticed months and months ago when trouble shooting it, I readjusted my Y gibs, they were a little loose. I eneded up just forgetting about it and just altering my Gcode to make each move separately until it gets to where it's going. Instead of X2Y2 on one line I would say X2, [new line] Y2, just to be safe. The weird parts is I use this mill all the time doing very complex 3 and 4 axis stuff and it never messes up until I get to shallow moves on a drill cycle; that is until yesterday I was doing some pocketing where there were some extremely shallow moves and it messed up, luckily I was there to Feed Hold and resetup.

Any help would be appreciated. I'm just worried that it's going to mess up somthing real important.

"...the X and Y axis lock up..." - What does that mean.  You mean neither axis moves?  Or only one moves?  Or one axis may, or may not move the correct distance?

Regards,
Ray L.
Regards,
Ray L.

Offline Chip

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Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #4 on: August 22, 2009, 11:22:12 PM »
Hi, Cartierusm

Try setting Sherline 1/2 Step Mode in ports & pins, or this xml below and see if it helps, It's one you posted on your 4 th axis topic eariller, Let us know, It should give your cont board's have a little more time to see Mach3's pulses.

What axis controls are your using.

Chip
Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #5 on: August 23, 2009, 01:13:46 AM »
Thanks for the help.

Himy, it seems that the one making the short move is crawling along and the axis that's supposed to do the long move locks up, but I think I've seen it reversed. Not sure if the one axis that's is moving if it's actually moving at the correct speed.

Chip, is the only alteration to the XML the Sherline part as I'd rather change by hand so I know what's going on. Also for axis control do you mean what stepper drives I'm using? I'm using Keling 8078 Drives, here's a link to their specs:

http://www.kelinginc.net/KL-8078.pdf

Offline Chip

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Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #6 on: August 23, 2009, 01:46:50 AM »
Hi, Cartierusm

Changing it on your own is fine, Sherline 1/2 Step Mode just set's pulse width's to 40 ms, I did notice that your step & dir Pulses were set low, dir being  set at "0" in motor tuning.

I'm  PM messaging you my phone #, If you'd like to talk about this problem.

Chip
Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #7 on: August 23, 2009, 02:03:23 PM »
Thanks for all the help and a BIG THANKS to CHIP for spending time with me to solve my problem.

I changed the settings to the Sherline 1/2 Pulse Mode and reran the program and it worked, I was ecstatic, then I tried again from the beginning of the program...then it didn't work DAM. So I went and changed the G00 move that it was stalling on to G01, which at that point in the code was 20 IPM and that worked. I remember months ago trying different velocities, but I guess I didn't go low enough for the problem to stop. So something weird is going on for those shallow moves as it doesn't happen during other moves with high rapids.

OH well I'm not a complainer, I'm happy the problem got solved and it's not like I'm make 40" moves to where I'd notice the speed difference.

Offline Hood

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Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #8 on: August 23, 2009, 02:58:57 PM »
I have the big brother to these drives on the coil winder, I now have a SmoothStepper on it but during testing I was using the parallel port and it needed 5 for pulse widths. Have you tried that? Maybe they are not happy with the extra wide pulse of Sherline.
Hood
Re: Need HELP Steppers Stalling on Shallow Moves
« Reply #9 on: August 23, 2009, 03:05:08 PM »
Hood, I tried the Sherline and it worked, then per Chip's suggestions unchecked the Sherline mode and went into motor tuning and changed Step Pulse and Dir Pulse to 10 saved the axis and restarted Mach. Tried it didn't work, retried Sherline didn't work, then tried Step Pulse and Dir Pulse at 5 and it didn't work. So I tried changing the G00 to G01 in the actual Gcode and that worked. Chip said that the Step Pulse and Dir Pulse should be the same, so just for posterity I kept the Step and Dir Pulse at 5. So it seems something electronic or mechanical is happening, but the problem got solved and I changed alot of my regular Gcode files in Rhino.

Are your Keling drives set at active low? Chip said something about that but I didn't bother trying to change them, Keling documents say to have them at Active Low so I figured I'd leave them.