Loft connecting same vertex twice

brett_sutton

I've created three lofts in my document which are almost identical in that each of the 'end sketches' for the lofts are the same shape except the are of slightly different sizes.


Two of the lofts work perfectly. The third however has gone a little wierd.

One of the vertices at one end of the loft appear to connect to two vertices at the other end.
Each end sketch has the same no. of verticies.

The only difference I can see is that the problem loft is adjacent to another extusion whereas the two lofts that are functioning are have no (parallel) adjacent extrusions.

You can seem my document here.

https://cad.onshape.com/documents/fae3550df7c64658a6c35c9c/w/888bd5116d12448a95970bdd/e/827090b68f3a4a3f97eb5f70

The loft is labeled 'the loft that is wrong'

with sketch 2 and sketch 3 been the two ends of the loft.

So is this a bug in onshape or a bug in my understanding?

Brett

r_paul

brett_sutton
Brett, I redrew your the offending form in sketch 3 and it worked fine.  At least it matches the lofted shape of the others so I am assuming its ok.
Suspect you may have had a duplicate/additional point or extra geometry which was being taken into account.
Have another go at redrawing yourself and see what result you get, I think you will be fine.

andrew_troup

@brett_sutton
Well, I can't find a problem with your method (without a major dissection, at any rate)

I think it's time to share the model with Support (under "Share" at top right), click on "Feedback" from the open model (under the ?), and submit a ticket.

r_paul

brett_sutton
Brett, I redrew your the offending form in sketch 3 and it worked fine.  At least it matches the lofted shape of the others so I am assuming its ok.
Suspect you may have had a duplicate/additional point or extra geometry which was being taken into account.
Have another go at redrawing yourself and see what result you get, I think you will be fine.

brett_sutton

Yes I redrew the sketch and the loft now works.

So as you said it looks like I had drawn over the sketch a second time (or at least had some duplicated vertices).

So solved it eventually, but it does seem like a short coming of onshape that its not easy to see if you have doubled up with lines or points within a sketch.

I eventually use the 'select other' which gave me some hint as to what was going on.

Not quite certain as to what to suggest, almost need a '3d expand' view for the sketch which shows you a 'layered' view of your sketch so you can see any duplicated lines or vertices.

But much thanks for your help.

andrew_troup

Hmm...

My first diagnostic step, having made an extra copy of the part studio for the purpose, was to select the five lines of each profile, making sure to use only five clicks, and delete them. 

The aim was to check that there were only five entities, and it seemed that there were.

This (it seemed to me) was confirmed when, having deleted them, no entity was revealed to have been overlaid by them.

So, particularly in the context of a beta product, it seems to me that submitting the original model to support would still be worthwhile, in the spirit of the "common good"

andrew_troup

In Solidworks, as I recall, multiple overlaid lines are flagged by a thinner linestyle than standard.

Perhaps Onshape need to consider something ... "along these lines".