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Generate dynamic belt spline around circle splines/shapes

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Hi all!

Please excuse if this is not in the right forum, kinda hard to pin down where it belonged 🙂

I'm trying to create a drive belt that is supposed to run around a set of cogwheels. For this I need a spline to wrap geo onto that runs the full course in a physically accurate way, as described by the red stroke in the top image in the attached PNG. Since I will need to make several of these setups and probably will need to tweak them alot along the way it would be great to figure out a way to create these splines without having to redo them manually every time. I have tried a Cloner set to Blend, containing two splines each, sitting inside of a spline mask set to Union. This almost works, but when I combine these setups in another spline mask it starts giving unpredictable results and also the whole setup quickly becomes quite clunky.

Does anyone have an idea of how to do this in a more efficient and/or flexible way? Or even a plugin maybe? I've been looking around but to no avail. Many thanks in advance for any pointers!


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  • Johnny Maunason changed the title to Generate dynamic belt spline around circle splines/shapes

Oh that's good news 🙂 Spline pen should mean you don't have to bother with any of the multi-stacked spline mask nonsense !


I timed myself making this with spline pen. 1 minute to place the initial points (no special tricks, just clicking and dragging over the reference), then 3 minutes in points mode tweaking tangent handles. The question is, did I get close enough for you ?




Fairly sure that even if I didn't it would only take a further couple of minutes of tweaking to perfect it...


Another point to consider is if the belt should touch the cylinders as it goes around them. If this going to end up dynamic for example then you might want your path spline to be slightly offset from each roller... also the quesiton of 'slack' which exists in every belt drive system I have ever seen to some degree...



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