Closing the loop with Linuxcnc, adding encoders to Mesa FPGA?

[Clive S]

If I'm going to linuxcnc route with encoders I really want dual homing, it just "completes" the picture nicely.
I can cut at 10m/min with great success but for some reason my sizes are out, my 3d carvings are coming out good.
I did some simple tests moving X 10mm then back to 0 1000 times same with Y not seeing as lost steps.
It also cuts the same size at 1m/min and 10m/min.
I only cut wood it's my thing, I don't even touch ply just real wood.
If I can close the loop using my AM882's with a breakout board for the Mesa step generator card I own and changing some motors I'll do it just for piece of mind.

I know you have said all this before but before you go down this route the machine should be made to cut accurately.

You are say it is out by about 1mm at 1M/min or 10M/min. That sounds like backlash or acceleration to high. I don't think changing the motors will help.

I would not attempt to close the loop until you get the gantry squaring sorted. Also closing the loop for a wood router in my opinion is a waste of time and money.

If you want to go with Linuxcnc I have a test ini file I could post that I know that works on a PP with V2.8 or 2.9 just for the that gantry squaring.

I have built a test rig for this from an old A frame type Prusa 3D printer with a motor on each side on Z running off a PP

[Desertboy]

I know you have said all this before but before you go down this route the machine should be made to cut accurately.

You are say it is out by about 1mm at 1M/min or 10M/min. That sounds like backlash or acceleration to high. I don't think changing the motors will help.

I would not attempt to close the loop until you get the gantry squaring sorted. Also closing the loop for a wood router in my opinion is a waste of time and money.

If you want to go with Linuxcnc I have a test ini file I could post that I know that works on a PP with V2.8 or 2.9 just for the that gantry squaring.

I have built a test rig for this from an old A frame type Prusa 3D printer with a motor on each side on Z running off a PP

It's a weird one Clive S, I cut a square indent it's 1mm undersized no matter what size the indent is but I move the machine 1000mm and it's spot on. I direct drive with couplings and everything is tight it's not slipping, I replaced all my couplings trying to solve this. My PSU is a Tolordial build, ~70v 1kva and 4 AM882's I'd be surprised if they're the issue here.

I've had the machine working for 2 hours doing a 30cm*40cm 3d carving with a R1 ball nose mill with 4% stepover this was spot on but the size was off.

When I cut 10 indents with a gap between them the indents were 1mm too small and the gap 1mm too large, tried with multiple tools of different sizes to be sure. I'm sure it has to be tool related but I had people check my gcode and it's good and I've had someone cut code I generated and there sizes were spot on.

I've also tried generating my code in Vcarve and Fusion to see if there was a difference, it's off, but it's repeatably off.

I definitely want the config file ;)

Not hooked it up to Linuxcnc yet, it's raining hard here today and I have the machine in a van so I need the weather to calm down a bit first.