pic: 3D Printed Gear Spacing Check

[Tristan Lall]

Originally Posted by Nate Laverdure

At the scale where your test results are useful (in the thousandths), this must be very sensitive to dimensional inaccuracies. How did you ensure that your printed gears were scaled correctly?

I had the same thought. Assuming you don't know the manufacturer's tolerances on the gear tooth profile, how can you be sure that this reflects the actual fit of parts chosen (essentially) at random off the production line?

Generally, gears of that size will still have reasonable involute contact without binding or substantially reduced load capacity (with less or more backlash), even given a few thousandths of an inch of variation in centre distance—so this was likely to "work" pretty well, given the constraints of the test.

Also, if it wasn't possible to measure the centre distance directly with the tools available, wouldn't it have been been more accurate to 3-D-print a pair of gauge pins to fit the mounting holes and measure between them (accounting for their diameters)? That way you'd be testing against a simple dimensional tolerance (which you presumably established during design), rather than a functional constraint (which is kind of tough to evaluate under the circumstances).


Either way, as a demonstration of the 3-D printer's ability to produce intricate parts, it appears to have been a success.