Centroid Community CNC Support Forum

Guys even if it is just a wild guess, let me hear it. I am really on my last wit here.
For some reason the x and z axis of my machine started to gain or lose steps. There are several posts on her about this. After working on it for a bit I am thinking that it is a static electricity problem. The control cables for the clearpath motors run through an E Chain alongside the other cables needed for the x an z axis, plus the limit switch, the fan for the spindle and probably something else.
Over the last couple of months I have done the following. Put the VFD on the wall and separated the vfd cables from everything else with the exception of the e chain. The VFD cable is well shielded very high quality cable. Replaced the 24 volt line for the spindle fan with a shielded one and put the fan on it's own 24 volt supply. The 115 volt power for the control box now comes from a different circuit in the building as the computer for the acorn.
After doing this I ran about 16 air cuts on a file that used the x axis heavily. Ran perfectly.

This morning I set up to cut a couple of wind wings for a friends MG automobile. I clamped the material and put a diamond drag in the spindle. Since it was a diamond the spindle was turned off for this run. It ran perfectly. Then I put a 1/8 inch three flute cutter in and tried to run the outline of the wing. My bad I used a cutter that I should not have and it broke. Better cutter in the machine and ran the file. The Y axis is perfectly on track the the X axis has now gained steps and is outside of the track that it should be on. I re-zeroed the X axis and it ran once round the track where it should and then lost steps. Now it runs inside of the track where it should.

I am putting two pix of the piece I am trying to run and also a fresh report. You can see in the pix that the logo (with the spindle off) ran perfectly four times.(Four wings on this cutting file) The when I turned on the spindle the problem is obvious.

What on earth could be the cause? Is the spindle going south? The VFD?

hmmm odd one for sure.. i think it is something mechanical slipping when there is a force on the X axis.
thats why you only see x "losing steps" when the cutter is being used.

Do you have your Clear Path settings configured to recover from lost steps?

Do you have the latest configuration for resistors on the step/direction/HLFB for the clearpath?

Keith
The problem has mysteriously gone from Y to Z and back again in the past. I put a new gear reduction and two new motors on the machine in an effort to find it. The connection between the gear reduction and the motor is the only possible place that slippage could occur. It is pretty robust!

Rog
How do I configure the motor to recover from lost steps. I have installed the resistors Clearpath calls for but how do I determine that they are the latest ones?

If your motor couplings do not have a keyway, which they should, then you must use Loctite 648 on them.

As for the resistors, Centroid wiring documents call for 100 ohm at 1/2 watt. If I remember correctly the Teknic manual wants you to use a 1k, 1/4 watt. That's not correct for Acorn. Follow diagram S14971 for the correct resistor wiring for Clearpath and Acorn.

I have Clearpath on my plasma and router with 100 ohm resistors and they work flawlessly. My plasma is capable of 1500 IPM and it's rock solid.

Tlempicke wrote: ↑Tue Feb 21, 2023 8:10 pm How do I configure the motor to recover from lost steps.

Refer to the SDSK manual, page 75 for position recovery.

The reference voltage for the clear paths is recommended to be +5VDC, there was a discussion and thread about this and resistor values https://centroidcncforum.com/viewtopic. ... 292#p47292

I changed the resistors and voltages as recommended, my system has been rock solid.

Checked the resistors and sure enough they were 1K. I ordered the C86ACCP board and this looks very promising.

Tlempicke wrote: ↑Wed Feb 22, 2023 7:07 pm Checked the resistors and sure enough they were 1K. I ordered the C86ACCP board and this looks very promising.

That board is gonna be more of a headache than it's worth. All you needed was 9 resistors from Digikey at $0.11 each. Good luck.

ShawnM wrote: ↑Wed Feb 22, 2023 7:17 pm That board is gonna be more of a headache than it's worth. All you needed was 9 resistors from Digikey at $0.11 each. Good luck.

+100

Not to be all captain obvious here but... are you sure you have a good tune in those motors?

The reason I ask is I couldn't get a good tune in mine even after wiping them starting over and auto tuning 3 times in a row on each motor on 4 separate occasions. (they say it improves with each successive). I was getting serious chatter/dime edging on circles. The motors also had a ton of shaft slop (like 5 degrees or more!) when I'd wiggle the shaft with my bare hand (,no pliers). After ripping the machine apart verifying pinion lash, belt tension etc, I contacted Teknic.

Teknic engineer dialed in and tuned it over the phone. Now there's no more shaft rock, no more chatter and it totally rips. You really ought to consider doing the same if you haven't already. I was almost ready to ditch them for closed loop steppers... I'd never seen a servo that loose before.