Forming a 'tooth' in context with an overall assembly

michael_browne

I am still pretty new to OnShape, so I am guessing this is my own unfamiliarity with the tools at hand, but I have been trying to create a kind of 'tooth' on a part that is meant to allow it to snap onto the next higher assembly, while still being possible to remove it non-destructively. The part itself is pretty simple, but it is clipping onto a curved surface, and I want the tooth to kind of wrap around underneath it, like this:

I have been playing around with the loft tool, but have had zero success is getting to loft over the 'pipe' the part is meant to grab onto. If I start the loft on the part, it is like the tool concludes "oh, I am already touching it - all set!" and then doesn't actually accomplish what I am trying to do:

But if I swap the order of the loft, I get this weirdness instead:

So, am I just misunderstanding how to use the loft tool? Need more practice with it? Using the wrong tool for what I am trying to accomplish? Conceptionally, this seems like it should be pretty simple, so I am guess the problem is how I am approaching things.

If someone wants to look at it directly, they can find it here:
https://cad.onshape.com/documents/9743c17aa5f5fc08c2ed6c0d/w/5e5752bb95d0ce127e9e246e/e/1f9b48e07ade2ec125736438?renderMode=0&uiState=668314b76a633b116f4a2826

Thanks!

S1mon

It looks like a simple extrude is all you need for the shape you've sketched.

michael_browne

S1mon said:

It looks like a simple extrude is all you need for the shape you've sketched.

Possibly. I was trying to do it in the context of the bar I am trying to get the tooth to grab on to, and drawing that kind of curve was proving to be a PITA. I was hoping that a loft would be a more elegant solution - if I could get it to solve at all.

robert_scott_jr_

It's not necessary to draw a curve to match the face of the tube. The Use tool within the sketch tools can do that. Extending the line of the S shape and adding an arc was done to complete the sketch. Does that satisfy your need? - Scotty

P.S. If a sketch is not fully constrained the some or all of the components of the sketch exist but are not defined as to their own attributes (length of a line, radius of an arc, etc.) or where they are. As you've experienced, creating a 3D object from an unconstrained sketch is possible but altering that sketch if needed can result in unexpected, unwanted movements in other sketch elements. That is what I experienced when trying to add the elements to your sketch. I had to first fully constrain your original sketch.

https://cad.onshape.com/documents/72e636073b423fea1e753b3e/w/f80abd4c242dec3658e66c5d/e/10d3ea583d8de1cfb3529965

michael_browne

robert_scott_jr_ said:

It's not necessary to draw a curve to match the face of the tube. The Use tool within the sketch tools can do that. Extending the line of the S shape and adding an arc was done to complete the sketch. Does that satisfy your need? - Scotty

P.S. If a sketch is not fully constrained the some or all of the components of the sketch exist but are not defined as to their own attributes (length of a line, radius of an arc, etc.) or where they are. As you've experienced, creating a 3D object from an unconstrained sketch is possible but altering that sketch if needed can result in unexpected, unwanted movements in other sketch elements. That is what I experienced when trying to add the elements to your sketch. I had to first fully constrain your original sketch.

https://cad.onshape.com/documents/72e636073b423fea1e753b3e/w/f80abd4c242dec3658e66c5d/e/10d3ea583d8de1cfb3529965

And here I thought I had constrained things sufficiently already - I am going to spend some time comparing your sketch and my own and see which constraints I missed... "Use" looks like it was exactly what I was looking for - thanks! Although, I dislike the very non-descriptive name for it; made it hard to google at first (not that you would have any control over this name, however)