[ANSWERED] Create lobed knob / Sweep along "wavy circle"

felix_fischer992

Document with all the tries in separate part studios: https://cad.onshape.com/documents/7d92ebfc4d42d67498b44c02/w/c3e079a016e5604e415d2895/e/8d83e605f9727daac7ef5c4f?renderMode=0&uiState=671eb1542b083d3d38a744a6

Any help on this would be greatly appreciated.

It is kind of tricky to put into words what I want to create, so here are two pictures of the kind of knob that I want to model:

My initial idea was to sketch the circumference using straight lines and arcs like so

…then thicken the core and sweep a semicircle along the outside perimeter.

This however only succeeds if I select three or less segments of the perimeter, otherwise the Sweep won't work and say "Lock direction causes invalid geometry" (even though I never selected lock direction anywhere.

I was able to kind of get what I wanted by separately sweeping the straight section, then a curved one and cutting off the "excess". The result of which I could put in a circular pattern.

This does seem like a very odd way of doing it, though.

jelte_steur814

I would always strive to create only one section of this geometry, cutting off excess if required, and putting that in a circular pattern. that is definitely the way to go.

That way if you add a fillet to the edge, Onshape only has to calculate that once and can just copy afterwards.

perhaps a loft with a path is the way to go for spanning the gap between two 'straight' sections.

rick_randall

Here is an example,

https://cad.onshape.com/documents/61ec28e939a493243b3f4f9d/w/17a712bc57cb3c92624aa976/e/72f12b5c1a5344ae2bac4379

I didn't spend much time on this, and finished form should probably be adjusted (but it demonstrates the workflow).

rick_randall

@felix_fischer992 - You might try this approach, revolve the basic round form, sketch necessary geometry required to cut one flute, sweep cut that shape one time , then circular pattern that sweep cut feature (don't forget to check the apply all instances box)

Good luck

jelte_steur814

I would always strive to create only one section of this geometry, cutting off excess if required, and putting that in a circular pattern. that is definitely the way to go.

That way if you add a fillet to the edge, Onshape only has to calculate that once and can just copy afterwards.

perhaps a loft with a path is the way to go for spanning the gap between two 'straight' sections.

felix_fischer992

https://forum.onshape.com/discussion/comment/108824#Comment_108824

Thanks a lot, that works a lot better and produces a result that is close enough to what I want.

I don't think it is perfect yet, since the knob in the pictures looks a little different, but it will certainly do for my purposes!

rick_randall

Here is an example,

https://cad.onshape.com/documents/61ec28e939a493243b3f4f9d/w/17a712bc57cb3c92624aa976/e/72f12b5c1a5344ae2bac4379

I didn't spend much time on this, and finished form should probably be adjusted (but it demonstrates the workflow).

felix_fischer992

Tank you for the example, I didn't quite understand your approach before but now it is clear to me.

This looks like the best way of doing it.