Part Scaling...(moved from Slic3r forum)

is it unusual to see having to scale your parts up by 6-7% to get them to print the right size?

my .stl files are all drawn in Solid Edge and are outputted at .0001 resolution...?! what gives?!

"6-7% is very bad. Have you calibrated the printer axis steps/mm and extruder?"

im running a delta with a duet board... essentially its a bigger version of a mini kossel.

20T pulleys driving the towers.. i have not checked the extruder but running a wade extruder... nothing exotic

1.8deg nema 17 steppers


.according to everything im reading 80steps/mm is what it should be given my parameters and thats what i have it set at....

if i have to adjust it up or down from there i am not sure how to figure that out.. care to shed some light on this?


"This more properly belongs in the Delta forum, but here goes anyway. 80 steps/mm is correct if you are using GT2 belts, 1.8deg/step motors and 20 tooth pulleys. Does the height of your prints come out correctly?

If the print height is correct and it is only the XY dimensions that are wrong, there are a couple of common reasons:

1. Diagonal rod length not configured correctly. I recommend you do not use auto calibration to adjust it, so use 6-point calibration, not 7-point. Measure it as accurately as you can, between bearing centres, and use that value in the M665 command.

2. Bearing spacing not quite the same on the carriages as on the effector. This causes the effector to tilt as it translates, and as the nozzle is somewhat below the effector, this affects the print size. If your printer uses Traxxas joints then you can use washers or shims to equalise the spacings. You can make a final adjustment by changing the diagonal rod length parameter in the M665 command. Increasing it will reduce the XY size of the print.

HTH David"

Edited 3 time(s). Last edit at 09/01/2015 09:13AM by Freebird01.

im printing a 30mm test cube right now. i know my rods are parallel as i designed the end effector and the tower carriages in CAD and after measuring they are within 1mm of each other. not enough to really effect much. i will measure the rods again when the print is done. they should all be the same length as i made an assembly jig when i put the rod ends on so they were all adjusted the same and locked down with the lock nut. i know i have a little wobble in the frame and need to add x bracing to keep the top inline with the bottom but that should only effect the layer stacking not really scale...at least not to the degree i am seeing the differences..

i will post up my findings. thanks!

1mm is quite a big difference. There is another thread on this forum in which someone did a simulation of a printer with not-quite-parallel rods. I have my delta set up for each pair of rods to be parallel to within 0.1mm.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

interesting....i print a 30mm cube and all the dims are only .2mm big...L,W, and H...

i was printing some prusai3 parts earlier and they were way off.... bolt pattern for the motor was way small.... bores were undersized...etc...

well maybe i spoke to soon...i remeasured everything (delta rod seperation) and they are within .1-.2 mm.... must have been how i was holding the caliper

Edited 1 time(s). Last edit at 09/01/2015 12:54PM by Freebird01.

It's very common for bores to be undersized in prints and there are several threads on this topic. If you are using slic3r, checking "External perimeters first" helps, but doesn't eliminate the problem.

Edited 1 time(s). Last edit at 09/01/2015 12:29PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].