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The old belt drive thing again
martin_kopplow
Member Posts: 1,192 PRO
I found a few public FS that can calculate the length of a belt, given the pulleys and their distance. That's nice, and here's to the people who wrote these, but it leaves me trying and tweaking untiI get to a combination of pulleys and belt I can actually buy. Also, at least two of the FS I found and tried ask for the belt thickness in the edit box and then appear to calulate the outer length of a belt and output that in the result and the part name, where the "Wirklänge" (is that effective length?) is actually required, and that is NOT the outer length. In the particular cases of these FS, that would then be the inner length, because these FS work on the cylinders of given pulleys, which touch the inner side.
So, compared to what these FS do, I usually seem to have the opposite probem: I know which sizes of pulleys and length of belts I can buy, and need to position the pulleys (or at least one of them) so as to match (one of) the belt lengths (available).
There are a lot of belt calculators online or as apps available, so I can find the appropriate axis distance for any one given combo, but it would be nice to have this parametric within the CAD model.
In my imagination, a belt drive FS would be based on input such as the pitch and tooth count. It might have an integrated library of the usual belt types. Pulleys as well as belts can only have lengths or circumferences based on a multiple of the pitch. Also, such FS would work on the effective length generated by a calculation, rather than on any given cylinders, in order to minimize room for error. The designer would then create the pulleys so as to match the FS output, rather than the outher way 'round. If there was a pulley creator FS that could be put in the feature tree after the belt calculation FS, that would be fantastic.
Since the Onshape Feature Scripts are still not organized in any kind of searchable library, and I cannot imagine this has never been adressed yet, I have to ask the community if someone maybe knows someting?