Thursday, August 27, 2009


Printing test-part

Inspired by a paper from Kruth et al. (2005, Benchmarking of different SLS/SLM processes as rapid manufacturing techniques) I also designed a benchmark model for the RepRap. It looks quite random but by printing it you can check whether your RepRap prints geometrically correct. I included the following features:

-vertical holes for M3, M4, M8 screws
-vertical hexagons suitable for M3, M4 M8 nuts
-horizontal teardrops M3, M4 M8 and hexagons for suitable nuts
-sharp edges with angles of 15, 30 and 45 deg
-thin walls 0.5mm, 1,0mm, 1.5mm and 2mm horizontally and vertically
-stair effect at sloped walls with angles of 15, 30, 45, 60 and 80 deg
-round corners, radius 4mm to 16mm
-gear teeth with 2mm wide teeth
-in addition to this, you can also check perpendicularity and parallelism of your printed objects, which were the general intentions of designing a benchmark.

You can download both the STL and the AoI file from SourceForge


Printing it took about two hours, so why not watching a fancy movie while your RepRap prints its benchmark.

The very first version included a complete horizontal hexagon for M8 nuts, but apparently this made the object to big in height, so I just cut it off, leaving just a small offset ;)

The gear teeth were not built as expected but as a round corner with a bubbled rim. I am also missing the 0.5mm thin walls. The 1.5mm walls consist of only two parallel strings and are not solid, there is a small gap between them in both directions.

can you put a link to those files as I was unable to locate them
I will have ago at this when I get home.

I have also noticed that walls between 2W and 3W, where W is the filament width do not get filled because the gap between is less than W. It would need a pass with reduced filament feed rate to fill the trench.
BTW, what do you mean by too big in height? It doesn't look very tall, what machine are you building with?
It has nothing to do with the machine,I think the STL file was corrupted. And after spending hours with AoI I just cut the critical part instad of fixing it properly.
Could you put it on Thingiverse please. Then people would be able to upload there copies of it so we can compare results.
Thanks a lot for making this. It will allow us to check a lot of important features!

Please do post it on
SVN is also a good place, but thingiverse is even more accessible.
Sorry for the delay but now it's also on Thingiverse...
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