Incorrect scaling (compression) in the X-Y plane

Hi all. I've just started printing and am having issues with scaling in the X and Y directions. For example, I tried to print a 20mm box and it comes out at 19mm x 17mm in the X and Y directions respectively. When the prints are smaller (e.g. one of the belt clamps for the Prusa Mendel), it's more noticeable. E.g. the holes for M3 Nuts in the belt clamp I printed are seriously out of proportion. (will try to upload photos soon)

I'm using Slic3r to generate the gcode, Pronterface as the host software, and Teacup Firmware on a Gen7 1.3 board.

I calculated the STEPS_PER_M_X and STEPS_PER_M_Y parameters in the Teacup header files quite carefully before compilation. Furthermore, Gcode motion commands work perfectly by themselves. E.g. g0 y 100 moves the Y axis 10 cm as expected - with a tolerance of approx. 1 - 3mm per 100mm. So I think my STEPS_PER_M_ are ok.

The 'scaling' option in Slic3r is set to 1 (i.e. I haven't scaled it at all).

Could this be a Slic3r issue? Am I missing something obvious?

Edited 1 time(s). Last edit at 04/20/2012 03:52AM by dslc.

The tolerance on a 100 mm move should be 0.1mm (NO MORE)!

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Check the motors are correctly calibrated, if they aren't they can skip steps.
Once the motors are calibrated correctly then re-calibrate the x and y axis. As rhmorrison said it should be calibrated to a far greater degree.
If your still having issues check the belts are tight enough and that they aren't slipping.

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My Reprap blog

jds-reprap.blogspot.com

Thanks for the advice guys.

Looks like the belt tension was certainly a factor - if not the sole cause of the problem.