How to cope multiple steel tube joints?

paul_noonan783

Hi All

I've created an engine mounting in Onshape that uses many, mainly 25 x 1 mm steel tubes (it's really a recreation of an old aircraft engine cradle from the early 30's). Anyhow I'm stumped on how to cope the ends of my tubes so they can be cut and welded. My model is at........

https://cad.onshape.com/documents/5c81b72d599bff002a251880/w/05f030f9ef00660eac588afe/e/2085231d3fd450d51d7e6a71

I got excited about the beams feature but it can't seem to deal with projected curves. At the moment I have only progressed a very small way, and that was by:

1) creating PART 1 by extruding a tube profile sketch - it's called "Extrude 2 - TUBE B"

(...2) creating PART 2 as a MIRROR of Part 1 - it's called "Mirror 2 - STBD TUBE B")

3) creating PART 3 by extruding a similar tube profile sketch. This intersects Part 1 - It's called "Extrude 1 - Port TUBE A"

4) using the sketch profile of PART 1 to extrude a REMOVE into Part 3, thus coping one end of Part 1 - the resultant feature is called "Extrude 1 - Copes the end of TUBE A"

You will see my drama though when you look at my joints of up to 8 intersecting tubes...........What comes first, the chicken or the egg? or the padded room, soothing music and basked weaving classes?

Indeed because my tubes need coping at both ends I think I would go mad. My next thought was to position sketch planes mid way along my tubes, extrude them in outward directions from that plane, and use the technique above to use 'remove extrusions' to cope the ends.But i still don't know if this is a good idea. Maybe I'm missing something obvious here.

Your advice will be much anticipated and much appreciated.

Best regards

Paul

NeilCooke

Beams relies on sketch planes to orient the profiles which is why it won't work on projected curves even if the result is a line. If you can do it without projecting, Beams will be able to do all the coping for you. Otherwise, it's Boolean/Subtract multiple times, then Delete Part for the slivers left over,.

paul_noonan783

Hi Neil

Thank you...... I suppose I could use existing projected straight lines to create planes and recreate the projected lines as sketch lines thence use Beams..I've never used Boolean operations, I still think that might be the easier path! Thanks again

Prachi

Paul
Here are some how to samples that you may want to study. I've done quite a few this way with success. There are some trims left to be done in this sample that can be done using existing tube sketches (extrude remove). Working in context allows extrude in 2 directions at once to existing faces. For the most part there are no slivers left behind to delete. Save the mirror left to right until the right is completed and you can make all left parts in one feature.  If you need to maintain larger tube diameters running into smaller tubes this will not work as well. Cross members from left to right go in last to be one part without mirror.

https://cad.onshape.com/documents/af0e2902f139ab1acfa7df0a/w/ce95918f5c3aafacab81da78/e/aa089a3b1829dc846f50375c

NeilCooke

Beams relies on sketch planes to orient the profiles which is why it won't work on projected curves even if the result is a line. If you can do it without projecting, Beams will be able to do all the coping for you. Otherwise, it's Boolean/Subtract multiple times, then Delete Part for the slivers left over,.

paul_noonan783

Hi Neil

Thank you...... I suppose I could use existing projected straight lines to create planes and recreate the projected lines as sketch lines thence use Beams..I've never used Boolean operations, I still think that might be the easier path! Thanks again

Prachi

Paul
Here are some how to samples that you may want to study. I've done quite a few this way with success. There are some trims left to be done in this sample that can be done using existing tube sketches (extrude remove). Working in context allows extrude in 2 directions at once to existing faces. For the most part there are no slivers left behind to delete. Save the mirror left to right until the right is completed and you can make all left parts in one feature.  If you need to maintain larger tube diameters running into smaller tubes this will not work as well. Cross members from left to right go in last to be one part without mirror.

https://cad.onshape.com/documents/af0e2902f139ab1acfa7df0a/w/ce95918f5c3aafacab81da78/e/aa089a3b1829dc846f50375c

paul_noonan783

Hi Glen

Thanks very much for this.  It looks substantially more sophisticated than mine. I'm likely to have a couple of similar applications for this construction, so study it I will.

Best regards

Paul