Y axis motors send the gantry to different distances

Hi all.

I’ve recently upgraded to the MFX Workshop lead screw setup. I haven’t set my steps per mm yet, because I’ve run into a problem with my gantry.

If I start it off at the front of the machine on the left hand side, and send it towards the rear a set distance, after measuring the distance with a ruler, it says it’s travelled ‘A’ mm’s.

If I return it to the front of the machine, send it along the X axis to the right hand side, then send it the same distance along the Y axis as the first measurement, it goes ‘B’ mm’s.

A and B values are different by up to 3mm.

The gantry is straight along the front of the machine, and moving it in the Y direction anywhere on the waste board sends it at 90 degrees from the X direction. But there’s a difference between the Y1 and Y2 motors somehow. There’s a tiny bit of wiggle in my lead screws, but it’s not much. I’m not sure if that’s somehow contributing.

Here are links to two 1 minute videos I did to explain the problem to MFX, in case anyone is into helping me out.

Is your entire frame not square and/or mis-aligned?

No. I squared it carefully, then had an engineer check it.

I can’t get your video´s to play.

However, make the effort to calibrate steps/mm as this will affect how the machine cope, and any errors will be compounded or affected. You don’t have to dial in it to perfection, but it should be close.

Then test for discrepancy.

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I just typed the links to the videos in my post, but the forum changed them to video players that don’t work for some reason.

Re: Steps. The reason I didn’t bother yet is because the Y motors are supposedly slaved together, so I’m just trying to work out what’s wrong mechanically.

I get that, but if they are way off in terms of steps/mm then travel and acceleration is way different than intended. This will affect how/when steps are lost. I suspect one of the steppers isnt following as good as the other, causing it to loose steps on the way.

For instance - if your step/mm or microsetting is off the machine may jog way faster or way slower than intended - this will affect performance. Right now your performance => 3mm offset.
Acceleration ratios will also affect this.

For now - derate $110 and $112 to 2000 and $120 and $122 = 200.
Then do a quick step/mm calibration.

Are they still 3mm off after same test?

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Thanks Haldor, I’ll test it and get back to you.