NCStudio to Acorn Retrofit - Issues cutting Arcs / Circles (Resolved)

[mlegary]

After converting my CNC over to Acorn from an older NCStudio PCI card I am now having issues cutting good arcs / circles.

The Aspire job when saved in NC-Easy (MM) works correctly with NCStudio 4.53.4, so it isn't a physical issue with the machine, I am missing something in my Acorn setup.

X,Y,Z are connected to Leadshine M542 Drivers set to 100,000 steps / sec
There are two Y drivers / motors, both connected to Axis 2 (original wiring from CNC manufacturer)

X, Y, Z are setup for 2000 Steps / Rev and overall turns ratio appears correct (4' X travel & 8' Y travel accurate within 0.5mm)
Aspire path was saved using Centroid (MM) post processor

Can someone give me some direction on what to troubleshoot on my setup?

[Gary Campbell]

You don't give your feeds, speeds or depth of cut, nor do you give your machine type or specs, but this is most assuredly a machine backlash deflection issue. Mostly in the axis going left to right on your workpiece picture.

[mlegary]

The machine is a Golden Sign GS1325 Router
https://web.archive.org/web/20051228160 ... raving.htm

Spindle is set to 20,000 RPM
Depth of cut is 2mm
Feed rates that I have tried are 500, 1000 and 1500 mm/min

Left to Right in the picture is the X Axis

I have used a dial gauge to try measuring backlash, I can't find an issue.
NCStudio doesn't have any handling for backlash that I am aware of and it is cutting fine with that controller, albeit a different post processor.

Would there be a good backlash setting to try in order to diagnose the issue?
Are you aware of something that NCStudio may be doing to compensate for backlash or a setting that I need to transfer over from NCStudio?

[mlegary]

These are the settings from NCStudio 4.53.4 that are working correctly with the driver / motors and VFD / Spindle.

In NCStudio - Config 3 the Acceleration settings do change the shape of arcs, but I'm not familiar with what those settings are or what a similar setting in CNC12 4.14 would be.

[Gary Campbell]

IF you didn't notice this anomaly before you changed controllers, you may have the Acorn set more aggressively, therefore issues will become more easy to spot.

This is not a software or setting problem. There is something mechanically loose/moving on the machine.

[mlegary]

IF you didn't notice this anomaly before you changed controllers, you may have the Acorn set more aggressively, therefore issues will become more easy to spot.

This is not a software or setting problem. There is something mechanically loose/moving on the machine.

I have moved back to my NCStudio card, ran with the same tool, spindle speed and feed rate (using settings posted in thread, different post processor) and the issue doesn't happen, when I wire it to the Acorn controller the issue exists.

Any idea what the acceleration settings from NCStudio do?

[Gary Campbell]

Have you verified that your computer meets the single thread benchmark?

[Gary Campbell]

Heres an easy test for you: Draw a 4 point star, 200mm outside diameter, 25% inner diameter. Toolpath it with a 6mm bit, outside profile, 1500mm/min, 13500 rpm, 3mm depth, 1 pass, conventional direction. Make sure the start point is on an interior corner.

I would cut this on the left side (X-) and Right side (X+) and if a single center drive machine in the center too. You can do this with either or both controls. but I think the results will be similar.

[mlegary]

Have you verified that your computer meets the single thread benchmark?

It didn't.
Got ahead of myself trying to use the software on the same computer as NCStudio rather finish the complete computer upgrade first.
I installed CNC12 4.14 on a newer system that has a single thread of 2100 and there is no issue. No backlash compensation needed.

Thanks for the advice!