Y axis off - between rough/detail type cuts?

So, I wasn’t paying attention (as usual) and I had my material set to 1/4" instead of 1/2" and doing a full cut out…or so I was hoping. I let it run, then figured I’d just stop the spindle, drop it back down to material height (using Easel’s Z down buttons) and re-run the carve at the new material height.

Now, I get that it’s my fault for screwing up the material, AND not ensuring that it was at x0, y0 - I just assumed that it went back to start just fine because mid-first-cut, there were no problems, nothing was “off”.

I started the second carve and it ended up going up and just a little extra “Y” on the first pass (and subsequent ones).

Aside from all my own mistakes, is there any reason why when the machine returns to home after a job that ran perfectly, that without moving the X/Y motors at all, it would be off just a touch?

This can be a number of different issues. The go-to response for y-axis drift is that the potentiometer on the gShield (for the Y-Axis, in this case) isn’t turned up high enough. The Y-Axis doesn’t get enough current when it needs to make a move, so it stalls out for an instant. The easiest way to test for this is to move the spindle to one of the corners and do very long jog motions. If you have a 500mm version, do a SINGLE 8" jog down the Y axis and make sure it runs smooth. If it skips or freezes, or makes a grinding noise, its definitely a pot. Typically you need to turn this up by about 1/8 or a 1/4 turn. Too high can cause thermal shutdown on the stepper chips, so adjust incrementally until your long jogs are smooth, then do another test cut to make sure.

Another potential issue is belt slippage, a number of different issues can cause this. Check your pulley set screws, make sure none are loose. Pull on the ends of the belts, and make sure the teeth are meshing properly. If not, use a zip tie, electrical tape, or heat shrink to make sure the teeth stay meshed.

Also make sure all wiring is secure, if a wire loses connection for a split second it can also cause an offset.

Let me know if this solve your issues.

Thanks for the response Eric.

I ran the job and completed it (at a smaller than thought depth) with absolutely no issues of drifting or being off at any point. I’ve also run a number of “single” jobs, up to 2 hours…never a slip or a hitch.

This was very specifically losing the step between end of carve and home, or home to start of carve. Now, it’s on me that I didn’t check 100% that it was back in its original position when I dropped the bit back down to workpiece height when I re-ran…but with what it was off, I don’t know that I’d have even been able to visibly see that in “home” unless I start using a tiny pen mark or something…though I had no intentions of doing a second run and wouldn’t likely have thought of that anyway.

Though now you say - rapids…that’s the “coming home” and “out to cut”…and it did go about 10" both ways.

I will go and run a simple long-jogging test. I’ve been wanting to do that anyway since I’ve read the threads about tweaking steps/mm on various motors…so this might just be the test I need.

Hi @AlanDyke

I agree with @EricDobroveanu this really looks like you are loosing steps in your Y-axis when moving in a rapid back to home due to low current… If I have it right, you are running your machine with NEMA23s

See here for how to fix the issue:
[Solved] Cutting wrong, loosing position

Rock on. I’ll do some rapid tests tomorrow and see about current adjustments as needed.

Yes, I have the 1000mm machine with NEMA23s.