x and y calibration issue

On my SmartrapCore Alu I am getting 20.07mm along one side and 19.50mm on the other side of a 20mm cube. I have tried altering the belt tension on one side then tried the other way around but the difference between x and y stays the same.

Should I be looking to change my x steps/mm relative to y?

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

So I tried that and predictably got a parallelogram not a cube.

Back to the belt tension I suppose. The odd thing is it was printing both sides reasonably close (within 0.05mm) before I changed to from 20t to 16t pulleys to see if it improved the resolution.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Have you checked for orthogonality of the axes? If X and Y aren't orthogonal it will print rhomboids instead of rectangles/squares.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Maybe your new pulleys are not round?

Yes the axes are orthogonal. It was printing perfectly cuboid cubes prior to the pulley changes. I will check the pulleys carefully.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Quote
DjDemonD
So I tried that and predictably got a parallelogram not a cube.

Back to the belt tension I suppose. The odd thing is it was printing both sides reasonably close (within 0.05mm) before I changed to from 20t to 16t pulleys to see if it improved the resolution.

Did changing the pulleys affect the resolution ?

When you changed the pulley size, did the belt relationship to the rails change? See: [defcon.no]

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
Holy1

Quote
DjDemonD
So I tried that and predictably got a parallelogram not a cube.

Back to the belt tension I suppose. The odd thing is it was printing both sides reasonably close (within 0.05mm) before I changed to from 20t to 16t pulleys to see if it improved the resolution.

Did changing the pulleys affect the resolution ?

Hard to tell, since if I am honest I was not unhappy with it before - but at first glance it seemed like such a simple mod, then why not try it.

I think the asymmetry was related to one of the y-smooth rods being 2mm higher at one end due to the way they are mounted, and the fact that I've revised that part to try to minimise resonance (it is a motor mount and smooth rod holder combined), This resulted in the x axis being tilted and it was approx. 2mm further away from the frame on the right than the left. I have fixed this now so the digital dentist got it right it was non-orthogonal axes.

It might change the belt geometry by a small amount but this is mirrored on the other belt, so the effect should be equal on both sides of the cube. However Im now using 101 steps/mm on x and y to achieve a 20mm x 20mm cube.

Edited 5 time(s). Last edit at 04/13/2016 11:07AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions