Messages

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 20, 2011, 02:14:48 PM »

Well I'm going to try out some Nema 23 380's and Gecko 540 with a 48v 12.5a power supply. We'll see if my problem goes away. We can't find anything mechanically wrong at this point....

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 09:06:06 PM »

I will try an even lower velocity and raise the accel. If it is the voltage, would getting a new power supply help? Maybe 48v?  My drivers only allow 3amps max, is that enough? Thanks.

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 05:09:21 PM »

Yes, I have already switched to exact stop mode and acceleration to 1, I have my velocity set at 75 and in Sherline mode. Accuracy is noticeably better at these slower speeds but not perfect yet.

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 04:50:49 PM »

It's the same PC that I was using when I had my 3' x 4' screw drive system and never had any problems, Accuracy was perfect.  Basically, I'm using the same PC, motors, drivers, power supplies as I was on my smaller system so the problem should be mechanical I would think. I'm thinking it must be the motors, drivers, or psu's. I've already checked for slippage, backlash and freedom of movement and all those check out ok.

Again, even though I may be under powered, I have not seen or heard any stalling, even running at 400ipm - something is happening on a much smaller scale. I'm still getting measurements that are .01 to .02 off when cutting parallel lines but the errors are smaller at much slower speeds.

Any other thoughts?  Thanks,
Jon

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 01:03:53 PM »

Gerry, I'm using Keling KL 4030 drivers with 2 24v 4.5a power supplies. One for the X&A motors and one for the Y&Z motors. I looked and I have the drivers set to 3a each. My Y axis moves very smooth and probably weighs 15 pounds or so. Of course my gantry probably weighs 50 -75 pounds but still moves pretty smooth.  Any advice would be appreciated. Do you think my problem is with the overall power & torque?  I can get better results moving very slow, 50-75ipm and low acceleration.  It will be a few weeks before I can upgrade the motors and/or drivers & power supplies. But I do need to make this work until then so I'm thinking I'm going to have to sacrifice speed for accuracy for the time being.

Do you think I'll get my accuracy back with better power & torque?

Thanks.

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 17, 2011, 09:23:05 PM »

It's spring engaged. It has a lot of tension and I've watched the gear and not even close to coming up off the rack. That's definitely not the issue here. Also, the changes in direction are not even close to being rapid or quick at 100ipm velocity and 2 acceleration.

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 17, 2011, 07:37:18 PM »

So let's say it has nothing to do with torque because I'm running it so slow. Should I even go lower with the acceleration? Maybe 1?  I was also told to put it in "exact stop" mode in the Constant Velocity settings, was that correct? Does this setting make a difference?

If it's not the torque (because it seems to be running fine and not stalling at all) What else can I check? I need to fix this without having to buy new components.  I have Keling KL 4030 drivers and they have always been reliable and accurate. I have 2 24v 4.5 amp power supplies, one for the Y&Z motors and one for the X&A motors. Do I need more amps? Better PSU's?

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 17, 2011, 05:53:35 PM »

Steps per unit on the R&P is ~1388 and the steps for the old screw drive was 8000.  My Z is still a screw drive and it's at 8000. They were all ACME 1/2" 2 start screws.

My drivers are currently set a 1/8 microstep. Do you think I can change them to higher or lower microstepping to get better results? Will that help?
Thanks,
Jon

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General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 17, 2011, 05:28:55 PM »

Yes TP, I have the CNC Router Parts R&P system, which has a 3:1 belt reduction. I'm also using 495oz NEMA 23 motors which should be sufficient. Again, I haven't seen any stalling or heard anything funny yet with the motors. I'm getting pretty good results keeping my velocity at 100ipm and accel at 2.  I ran my 2" line test again and it seems to be getting much better. I actually have my power supplies for the motors & drivers plugged into their own circuit, separate from the router, computer and dust system.

10

General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 17, 2011, 03:07:53 PM »

Ok, I will stick a sharpie in the collet and draw some lines with the router off and see if there is any difference. What other mechanical issues could there be? Keep in mind that I have checked & tightened all the motor shaft pulleys, tightened the belts, even tried to move each axis by hand to see if there was any play or back lash issues in the rack & pinion and all of these checked out ok. What other mechanical things should I look at?  My motors are not whining or stalling either. 

Could the difference in wiring be a factor? Having the Y & Z motors using 18ga shielded wire and the X using 22 or 24ga un-shielded wire?  I'm going to switch the X today over to the heavier shielded wire just in case.

Thanks,
Jon