Steel square tubing framework from complex sketch

[ecorm]

My version info is at the bottom of this post.

I'm designing a mirror support structure for an amateur telescope that will be made out of 1" steel square tubing. A mirror support looks like this:

Custom+Mirror+Cell+Product+Shot.jpg (30.47 KiB) Viewed 1168 times

Mine will be different, but the above image is just to give an idea.

The dimensions are tedious to calculate by hand due to the complex geometry, but I found that spreadsheets and sketch constraints have simplified the process. Here is a screenshot of the elaborate sketch used to determine the outline of the structure.

MirrorCellSketch.png (133.07 KiB) Viewed 1168 times

I was then able to pad the sketch to obtain this 3D part.

MirrorCell3D.png (11.15 KiB) Viewed 1168 times

I would now like to extrude the profile of 1-inch steel square tubing along the framework. This will allow me to use FreeCAD to calculate the volume (and thus the weight) of the framework. However, I don't know the best way to proceed. Some guidance would be appreciated.

If it matters, I'm using the Assembly 4 workbench. The steel framework will be but one part of a more complex design.

Cheers,
Emile

OS: Linux Mint 20 (X-Cinnamon/cinnamon)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.
Build type: Release
Branch: unknown
Hash: 9e3b630bbfb6807e93eeffb655e6c20f218644fc
Python version: 3.8.5
Qt version: 5.12.8
Coin version: 4.0.0
OCC version: 7.5.1
Locale: English/Canada (en_CA)

[chrisb]

I would now like to extrude the profile of 1-inch steel square tubing along the framework.

I'm not quite sure what you mean. "Pad" is the PartDesign equivalent of Part's "Extrude", so it is already extruded. If you mean you want to have square tubes instead, then you could try thickness.

Besides: Your sketch looks awfully crowded. You should simplify it. First step would be to model only half of it, and use mirror. Next you should eliminate all double dimensions if possible.

[ecorm]

Sorry, I meant to cut the profile of a square steel tubing along the length of the solid shapes that were created via Pad. Perhaps that idea was nonsense. If it's better to use a different tool (such as thickness) from the raw sketch, then I'll try to do so.

I agree the sketch is a mess, and I'll go back to it and try to simplify things.

[papyblaise]

you have to make each tube one by one in separate bodies or separate elements in Part (workbanch that I would use) then fusion them
you simplify by making a mirror from right to left
and attach us your file
just for my information, I thought that the canadians used the mm like now the english

[jmaustpc]

I would now like to extrude the profile of 1-inch steel square tubing along the framework.

Like ChrisB said, with what you have already modelled a PartDesign Thickness feature could be a solution, but it will have limitations including being susceptible to topological naming issues (hence will not be a robust model if/when modified).

However if you don't object to starting again, then I think you could be better off sketching the paths that the tube would follow, then sketch the vertical cross section and then extrude that cross section along the paths using a PartDesign Sweep feature. You would need multiple Sweeps since you will have to sweep each section separately. You could do that as features of the same body so long as at all times the result is one single solid. Generally it is best to keep the workflow in one workbench where appropriate, for example, you can mix Part WB and PartDesign WB if you know how and do so correctly, but doing so adds more complications, things to learn potential for confusion etc.

[ecorm]

Like ChrisB said, with what you have already modelled a PartDesign Thickness feature could be a solution, but it will have limitations including being susceptible to topological naming issues (hence will not be a robust model if/when modified).

However if you don't object to starting again, then I think you could be better off sketching the paths that the tube would follow, then sketch the vertical cross section and then extrude that cross section along the paths using a PartDesign Sweep feature. You would need multiple Sweeps since you will have to sweep each section separately. You could do that as features of the same body so long as at all times the result is one single solid. Generally it is best to keep the workflow in one workbench where appropriate, for example, you can mix Part WB and PartDesign WB if you know how and do so correctly, but doing so adds more complications, things to learn potential for confusion etc.

I think the Thickness feature will not model the "walls" where the steel tubes connect for welding, thus the volume/weight calculation will be off.

I'm willing to try your suggestion of sketching the paths of the tubes, then applying the Sweep tool. This would give me the opportunity to draw a cleaner sketch if I start again from scratch.

[ecorm]

I think the Thickness feature will not model the "walls" where the steel tubes connect for welding, thus the volume/weight calculation will be off.

I'm willing to try your suggestion of sketching the paths of the tubes, then applying the Sweep tool. This would give me the opportunity to draw a cleaner sketch if I start again from scratch.

On second thought, if I sweep the entire tube path in one go (if this is even possible), then it will also not model the interior walls where the steel tubes connect.

If I sweep each path segment separately, then there will be gaps where the steel tubes join at an angle.

I think I may have to model the tubes one-by-one from the same master sketch, and then join them like papyblaise suggested.

[ecorm]

just for my information, I thought that the canadians used the mm like now the english

While Canada has officially adopted the metric system for a long time now, most construction materials are still measured in imperial units. This probably has something to do with our largest trading partner being the United States.

We use different systems of units for different things in our lives. Speed limits are in km/h, but everyone still tends to measure their body height in feet and inches, and their weight in pounds. Beverage volumes and gasoline are in metric, but everyone tends to measure their fuel efficiency in miles per gallon. It's a veritable mish-mash of units.

Most high-tech engineering stuff is done in metric.

[chrisb]

Perhaps this is what you want: Draw a sketch with cutting lines and use Part SliceApart. Then use Part thickness on the individual pieces.

PartDesign Sweep can create tubes, but sweeping all in one go will not work.

[papyblaise]

In England (I lived there for 5 years around 2000) it is still a bit complicated in everyday life because of the habit of the "Oldies", the road distances are always in miles, or the pints of milk and beer
for your frame, here is an example in Part, you still have to mirror and fusion
you will notice that for the angular tube, the thickness function does not work, I had to make a full and a hole and subtraction