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Connecting up elements in a rotary pattern

iain_downsiain_downs Member Posts: 29 ✭✭
I'm trying to model a cycloidal gear.  I create a single tooth form on the pitch diameter and then generate the gear using a rotary pattern in the sketch.  All that seems to work fine, however, the sketch is not seen as a closed shape because even though one tooth starts where the previous tooth left off (at least as far as I can tell) the points are not seen as coincident.   I would imagine that if I marked them all as coincident it would all start to work, but with 96 teeth (and several wheels) that would be tedious and sort of spoils the point.

How should I do this

Comments

  • iain_downsiain_downs Member Posts: 29 ✭✭
    Ah.  I tried it with a 12 tooth pinion and it just worked.  I've then gone back and made the end of the pattern and the start of the original tooth coincident and, after a bit of mucking around it's worked.  I suspect with a high copy count there was a slight numeric error which prevented them coinciding.  I also had to remove one of the construction lines to make this work so my model is probably a few microns out now.  That's not an accuracy issue my skills will need to worry about
  • _anton_anton Member, Onshape Employees Posts: 47
    If possible, it's best practice to make one segment and then use a circular part pattern to make the whole part. A sketch pattern can be harder to operate and you can't set its instance count to a variable (in a parametric way).
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