# Calibration cube, top and bottom have different widths

**URL:** <https://community.inventables.com/t/calibration-cube-top-and-bottom-have-different-widths/30388>\
**Category:** Troubleshooting\
**Created:** [November 22, 2016, 1:58am UTC](https://community.inventables.com/t/calibration-cube-top-and-bottom-have-different-widths/30388 "2016-11-22T01:58:09Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ChristopherMayhew](https://avatars.discourse-cdn.com/v4/letter/c/b782af/32.png) [@ChristopherMayhew](https://community.inventables.com/u/ChristopherMayhew)\
**Post date:** [November 22, 2016, 1:58am UTC](https://community.inventables.com/t/calibration-cube-top-and-bottom-have-different-widths/30388/1 "2016-11-22T01:58:09Z")

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All,

I noticed during some cuts that the wall widths at the top and bottom of a cut were slightly off. So I cut out a 30mm \* 30mm cube (because it’s quick) to test out what is going on.

The short story is the the bottom of the cube is winding up ~0.015" / 0.381mm wider than the top (so roughly an extra 0.0075" / 0.1905mm on each size), measured via caliper. This is fairly consistent regardless of endmill, having tried 1/8 upcut and straight, and 1/4 upcut.

Any thoughts on troubleshooting? I’m trying to machine finger-joints, but the variable width from top to bottom of the cut is throwing my tolerances off. It’s not like my cuts are skewed, it’s more that the width from face A to face B (parallel) is increasing as the endmill cuts around them.

Thanks,  
Chris

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**Author:** ![AbearDesign](https://avatars.discourse-cdn.com/v4/letter/a/ecb155/32.png) [@AbearDesign](https://community.inventables.com/u/AbearDesign)\
**Post date:** [November 22, 2016, 4:43am UTC](https://community.inventables.com/t/calibration-cube-top-and-bottom-have-different-widths/30388/2 "2016-11-22T04:43:19Z")

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initial thoughts, stepper motors might need calibrating, belts, check for square.

> [@Consolidation of problems/solution threads](https://community.inventables.com/t/consolidation-of-problems-solution-threads/17123):
>
> I am working on consolidating the most helpful post on various subjects in order to make finding solutions to common issues easier. When I was fresh to the machine and it’s problems, I had to figure out how to word the searches in different ways in order to find solutions. I am still finding older post that were worded slightly different that didnt show up in my original searches. For now, it is just links to the post, however, I plan on creating more of a at a glance problem/solution referen…

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**Author:** ![SeanKeplinger](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/seankeplinger/32/82073_2.png) [@SeanKeplinger](https://community.inventables.com/u/SeanKeplinger)\
**Post date:** [November 22, 2016, 11:11am UTC](https://community.inventables.com/t/calibration-cube-top-and-bottom-have-different-widths/30388/3 "2016-11-22T11:11:37Z")

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What spindle are you running? I had a similar problem when running the 24V spindle – it was causing interference with the steppers. Try attaching a marker to your X-axis gantry and running a job (with the spindle off) to draw a square several times and see if you experience the same thing.

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**Author:** ![ChristopherMayhew](https://avatars.discourse-cdn.com/v4/letter/c/b782af/32.png) [@ChristopherMayhew](https://community.inventables.com/u/ChristopherMayhew)\
**Post date:** [November 22, 2016, 5:47pm UTC](https://community.inventables.com/t/calibration-cube-top-and-bottom-have-different-widths/30388/4 "2016-11-22T17:47:55Z")

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I’m running a Dewalt 611. Belts have been tensioned with a hanging-scale (type with a hook), steps/mm calibrated on all axis using a combination of the wasteboard grid and a depth gauge, and everything checked for square.

I’ll give the marker thing a try at different heights.

My initial thought was maybe something to do with bit deflection…

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**Author:** ![GregCross](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/gregcross/32/30243_2.png) [@GregCross](https://community.inventables.com/u/GregCross)\
**Post date:** [November 26, 2016, 12:56pm UTC](https://community.inventables.com/t/calibration-cube-top-and-bottom-have-different-widths/30388/5 "2016-11-26T12:56:23Z")

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maybe your spindle is not square to floor/wasteboard ,  
i managed to square mine up by adjusting the v wheels to close the gap when i held a square against x/z carriages