Tolerance Tester

This was inspired by the one from Maker's Muse. Except 5 hours for a test was a little much, so I designed a much smaller one. Here is a quick 10 min test tolerance test. Well, actually 11-12 mins on 0.2 layer height or 8-9 mins on 0.2 layer height. This is the smallest tolerance gauge I could make that was still structurally sound.

I have included the various tolerances from 0.10 to 0.3. If you want to adjust something, you can get the fusion 360 file here: https://a360.co/2rC0wYY

The gist of how it works is the "Tol" variable sets the gap between the core and the frame. If your printer is not precise enough, the gap may be too small/overlap and fuse together. That will prevent rotation so you would need to try the file one step up. If it's just one layer fusing, you can usually pry it to free up rotation. If you find a file that rotates freely immediately without prying, that should be your default gap size when designing parts that move.

If your bed isn't perfectly level or if nozzle height is too low, you may end up with elephant foot or fused bottom layers. I have added a chamfer to this one to compensate for this. You can also try the flat base versions if you think you have perfect level and nozzle height.

If the core isn't a perfect circle base, then your nozzle height is probably too high and dragging filament.

0.3 is quite easy, and 0.15 tolerance is very good for most printers.. 0.10 tolerance is much trickier and is possible with 0.10 or 0.15 layer height but I haven't had much success with 0.2 layer height.

TIP

For iterative testing, a good trick to try with this, is to print the first layer and stop the print and inspect. If the gap is already fused, it would fail anyway. If it's not circular, would be a nozzle height/z-offset issue. That would only take 30 seconds or less. Start a new test and stop around 5-6 mins right after the tab is finished. If it rotates freely, you're good to go.

If your slicer has that option, always print external shells first to get accurate tolerances.