How do i stick fins on a cylinder in an assembly?

matt_farkas

Extruded a circle to make a (hollow) cylinder. Don't see how to add mating connectors in the extrude. In the sketch, it's just a circle.

Made a separate fin part.

Yah, I'm new to CAD and Onshape.

brian_brady

Take a look at this:

https://cad.onshape.com/documents/57f7fa10d9d05d10ebf605a2/w/bb4e37435a2021c1dc41b888/e/4e6237a1c9b69c38a0630c9b

I placed 4 mate connectors on the tube by first adding points to the initial sketch. I realigned 3 of the connectors to make the z-axis for each normal to the tube. Then in the assembly I used those connectors to add the fins.

TimRice

If you dont mind your document being public, you could share a link to it here and we could take a look at it directly. Alternatively, if you would like your document to stay private, feel free to submit a support ticket.

matt_farkas

yah, take a look
https://cad.onshape.com/documents/64fc2f49c879e9a688bb3444/w/9b3173d52b7fe439b8b0c941/e/51853d910634b3a7b3a63cbb

matt_farkas

actually, here's the assembly https://cad.onshape.com/documents/64fc2f49c879e9a688bb3444/w/9b3173d52b7fe439b8b0c941/e/66a31223a2a4edef3c1db97a

jackson_king

How many fins are you looking at adding in the assembly?

matt_farkas

4 to 16, depending... in this case four an arbitrary point from the bottom, but might like to add more higher, later (they are to guide the tube into a square container)

matt_farkas

the fins have a flat bottom that will be welded to the tube... is this the problem? onshape can't mate a flat surface to a curved surface? or do i have to put mate points manually? i saw in some other discussions folk mention this, but i have no idea (can't seem to sketch on the curved surface of the extrusion)? there must be an easy way to do this... a colleague described how to do it in solidworks in several steps (i.e., stick flat edged fins on a tube)... i don't see any curvy examples in the tutorials... perhaps some should be added?

TimRice

I think in this case you would be better off modeling the parts in a Part Studio. This will give you much greater control over the location of the fins on the tube. In general, the assembly studio is best used to check dynamic movement and relations between mates and is not as well suited for static assembly of parts.

matt_farkas

you mean like this: https://cad.onshape.com/documents/64fc2f49c879e9a688bb3444/w/9b3173d52b7fe439b8b0c941/e/c741e4c2819c989791748cba

but then how do i add more fins higher up? do i have to extrude the full length then cut out what i don't want? even the current drawing is wrong in that the real fins have a flat edge that will be welded, but in parts studio it made a nice curved edge...

if assembly is all about moving parts, why have the fasten option?

so i guess you're saying there's no way to stick fins on a curved surface in onshape?

brian_brady

Take a look at this:

https://cad.onshape.com/documents/57f7fa10d9d05d10ebf605a2/w/bb4e37435a2021c1dc41b888/e/4e6237a1c9b69c38a0630c9b

I placed 4 mate connectors on the tube by first adding points to the initial sketch. I realigned 3 of the connectors to make the z-axis for each normal to the tube. Then in the assembly I used those connectors to add the fins.

matt_farkas

THANKS!!! i'd tried to do that (with a point, a line segment and a plane) but failed.... once i knew it could be done that way, i figured it out (that re-align is a bit odd for this newby)... i knew there had to be a straightforward to do it

matt_farkas

note (in same project) i figured a sort of hokey way to do it with extruding and "fixin'" the parts in the assembly... seems like it could cause problems at some point; looks fine and can do a drawing with it; thanks again