Perfect Trim/Extend on tube weldment joints 1

[skhizzo]

I'm trying to model a tubular chassis accurately to be able to export the cut list and begin building but I'm having some difficulties getting the trim/extend feature to trim/extend the pipes the way I want it. Maybe I'm just not doing the trims in the right order, or maybe making the structural members in the right order.
I can get a square weldment to look the way I want it to, but when you have three or more intersecting tubes, it just doesn't work out for me.

This shows 5 pieces intersecting, as you can see the feature trims the 'to be trimmed'(TBT for short) tube well beyond the boundary body. It doesn't seem to stop trimming at the first boundary. If there's another boundary tube that doesn't intersect the TBT, the TBT tube would be trimmed as if the second boundary was infinitely long. A clear example would be the one in the following picture:

The following picture shows how two structural members of different OD's don't join at their centerlines. The centerlines are perpendicular, but they don't connect at their centerlines.
Is there an option for them to join correctly?

This picture shows the same problem of the two tubes not joining at their centerlines. These have the same OD but are connected at an angle. Obviously, this is not a desirable trim.

Any help is appreciated! And thanks in advance.

 

[skhizzo]

Apparently I don't know how to post pictures in the thread here. Picture links -
First picture:

http://files.engineering.com/downlo...0-f32e-4a0a-9b59-232f7e0758d1&file=5PIECE.JPG

Second picture:

http://files.engineering.com/download.aspx?folder=694f60b0-8ed7-434e-a4ff-47950bd6ab2a&file=4p.JPG

Third picture:

http://files.engineering.com/download.aspx?folder=c49491b0-eda2-4ba9-bba4-93cbe1ab4c47&file=22.JPG

Fourth picture:

http://files.engineering.com/download.aspx?folder=b6e04416-8517-4100-9135-657a33592ea4&file=2.JPG

I don't see an "edit thread" button so my apologies for posting twice.

 

[Eltron]

What I find with weldments is that you just need to futz with them a bit. I was able to quickly do what you were asking by monkeying with the trim/extend settings. It would be easier to troubleshoot if you could post an example.

Dan

http://www.eltronresearch.com

Dan's Blog

 

[CorBlimeyLimey]

If the Weldment Trim function isn't working for you, you many have to resort to creating Zero Offset surfaces, and use the Cut With Surface function.

 

[skhizzo]

I tried to isolate each problem by rolling back and deleting some things but the problem would be gone. It had something to do with the angles where 3 or more tubes are intersecting onto one point.
Although, I drew the exact weldment sketches of the joint with an extra line/structural member connected away from the joint. For example, if three tubes connected in a Y configuration, extra members would connect to each leg of the Y. Anyhow, the exact weldment doesn't have the same problem, even with same trim orders and corner treatments.

I think I've got it squared away though.
First problem was solved by just doing extruded cuts of the boundary tube profile along the path and manually selecting the TBT tubes.

Second and third problems(actually one problem) was solved at first glance by changing the pierce points of every tube profile at the center of the profile. The problem with this is that if I only do a couple tubes, it won't line up with another tube so I'll have to change the pierce point of those subsequent tubes. Anyone see a problem with doing it this way? It's just a small shift, but I can't figure out why it doesn't put all profile centers as the pierce point. Or why the centerline of the profile is offset from the automated pierce point when you click on a sketch line.

Thanks for the suggestions.

 

[skhizzo]

Alright... I guess I just needed to fiddle with this some more. I figured out that the default pierce point for weldment extrusions is the origin of the profile. I didn't think the origin would return to bite me in the butt later, but I didn't put the center of the profile on the origin. Everything is fixed and the model is happy again.
Hope this helps someone else in the future.