Centroid Community CNC Support Forum

Last year I purchased an AcornSix board for a 48x96 Vytek laser table. All went well with the upgrade -- travel on five axes and homing. I had only one persistent problem with my paired XA and XB axis. Over 8 feet of travel, XB went roughly 3/16" further than XA. When given a G0X96 command, movement starts smooth but soon stutters and jumps till one of the servo drives faults as XB advances faster and further than XA.

If I disengage the rack and pinion on either XA or XB and drive one side solo, movement is smooth 30 IPM or 2000 IPM. Paired together the gantry's movement isn't usable.

I switched motors back and forth, drives back and forth, planetary gears back and forth, even power and encoder cables. Consistently, axis 4 of the AcornSix board sent whatever drive/motor combo it commanded further than the other paired drive/motor.

Finally I switched out the AcornSix with an AcornCNC board from a plasma table that I'd decommissioned last fall. With it, XA and XB were perfectly synchronized with identical travel distances all the way up to 2000 IPM. I wish I could use the 4 axis AcornCNC but the table has two Z axes. I have a 400 watt CO2 laser for one Z and a diode laser on the other Z. I need 5 axes and 2 PWM signals. AcornSix meets both these needs.

X and Y motion on the table is with Yaskawa drives and motors. Z1 and Z2 have stepper motors. Attached is a Report and photos. Excuse the wiring mess. I rerouted power cables away from signal cables in the wire ducts to eliminate interference as a possible cause. All encoder and power cables are shielded and grounded on one end.

I want to conclude that the problem is uneven motion commands from my AcornSix board. Is that possible?

If you post a report we can look into it.
Your vintage of AcornSix may need a firmware update to resolve issues with drives that have a low pulse input rate.
Did you use 5V step and direction and the same step rate for ACORN and AcornSix tests?

At what point going backwards do the Acorn Six boards need a firmware update for this? Can you share a date or serial number where the boards need a firmware update? Thanks.

I used the open collector terminals for the AcornSix. I used the same step rates for both boards.

The board is labeled PN, 15114, QC461 with a date of 3/15/23.

Just to clarify a bit more. I used the open collector terminals for the XA, XB, and Y axes. I used the 5V step and direction terminals for the two Z axes.
I thought I posted a report with my first post. Not sure why it didn't appear.

I'm hoping that the firmware is the problem. Now that I switched back from the AcornCNC to the AcornSix, only the XB axis provides movement.

Good Morning,

Any thoughts on whether a firmware upgrade will solve my AcornSix problems?

Thanks

Rich

Your AcornSix should be sent back for update. There were 3 updates to the ACORN_6 FPGA and 2 to the MPU12b FPGA since your unit shipped. There is one update that may be relevant to your issue.

The issue that may be corrected with firmware is lost position counts on drives with low maximum input rate. If an axis is no longer moving at all, that is something else, perhaps faulty wiring.

Are both servos for X completely configured the same?

Uwe

Yes they are. Identical parameters set is SigmaWin+. I also switched servo drives and motors between axes to determine whether there was anything defective in them. The distance discrepancy followed the output from the AcornSix.