I’m working on squaring and having a bit of trouble - I’ve discovered that there’s a difference in Y axis length on either side, a massive 10mm.
I don’t understand how.
I thought I must be measuring wrong or making a mistake, but I’ve run the tests 3+ times and get the same result. One side (rail side) from Y home to 2400 results in 2410. The non-rail side is a perfect 2400.
This is a straight line on one side, not diagonal for squaring.
The belts are the same, from the same initial length. Not too tight, not too loose, both about the same tension.
I home all axis. To surface and mark with pen mount (sturdy and doesn’t move). X to other side, mark. Y+2400 and mark. X home and mark. Four dots, each corner.
Any ideas?
Cheers
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Tested more just to be sure I’m not imagining it or messing up the measurements - same result. Nearly 10mm over the 2400 on the rail side.
This isn’t a y offset issue right? Because that results in a parallelogram as both sides will still move 2400, just at a slant. This is something different, one side is moving more.
X- to X+ are the same distance at both ends of the table, no problem there.
Yes the pulleys are all from the same local source, everything on either side matches source-wise.
I can’t think of anything else it could be other than a belt/pulley issue - maybe I can try new ones just to be sure, switching them out isn’t too much hassle I think. I hope. I planned to loctite the pulley steppers at some point so I guess I can do it when changing them.
I just tested in increments, so 0 - 500, 1000, 1500 etc and the gain is gradual, so I’m fairly sure that does point towards a belt/pulley issue?
It might even be a dreaded grub screw issue saying that, last issue I had was a very slightly loose one on the Z axis. Just had a quick check and it’s not loose but I’ll take out the stepper, re-do the pulleys and loctite them on both Y axis just so I can clear that possibility and have peace of mind. If that’s not it then I’ll change the belt/pulley.
Where are the belts from? We’ve observed multiple instances of belt teeth spacing differ enough to be measurable over 8ft lengths. Even when cut from the same self sourced cheapo belt spool.
But even then, variance has only been 1-2mm or so for ~8’ builds like yours. So, a 10mm variance is shockingly large (and an interesting number…), unless you share these were discounted close-out sale from temu or something?
Consider ordering belts from Ryan, or a supplier he recommends. Ryan’s tested and vetted and few different belt manufacturers now.
They’re cheapo ones from AliExpress. I bought 10m and cut all belts from that.
I actually had issues with it due to the thickness earlier in the build, I was struggling to fit them in the belt holders and for the X axis I had to buy a different belt altogether as it was too thick and I just couldn’t get it to fit in the side plate.
I think the typical belt thickness is 1.38mm and when dealing with it not fitting well I discovered this one is 1.51mm, so a little thicker than usual.
Possibly the thickness is not the only abnormal thing, the pitch or just general build might be, but as you say, ~10mm is a fair amount, so not sure. Also strange that only one side would be affected, because the other is spot on. (Unless they’re both off by a few mm in opposite directions )
Switch your Y steppers at the controller and the limit switch connectors too. Run rhe test again, if it follows the change you know its hardware ( most likey tooth pulley diameter
If expected 2400m motion is actually, consistently, overshooting by 10mm on one Y stepper side, then my money’s on belts with teeth pitch being stretched and off by 1%.
If still troubleshooting after checking/trying suggestions from other folks, could also try swapping the Y belts and see if/how behavior changes to help narrow down cause(s).
I don’t understand how.
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belts with teeth pitch being stretched and off by 1%.