Fabrication with Compound Angles

Hi everybody

I am making this post to hopefully get some inspiration to solve a current task I am struggling with.

I am trying to detail a metal beam shoe which is proving tricky.

The shoe straddles a glass beam which is 6.4 degrees off horizontal and has to support 2 glass beams at 45 degrees which are 9.1 degrees off horizontal.

I have drawn the beam shoe in SketchUp, but I am not really sure how to detail it in Layout. I am wondering whether I can give the fabricator the developed shape to bend it from in one piece rather than the individual facet shapes to weld it up from.

Any ideas gratefully appreciated as always :+1:




Here is the beam shoe geometry.

Beam Shoe X.skp (24.9 KB)

Have you spoken to the fabricator to see what they would want?

Have you had similar pieces made? Seems to me that frabrication would be easier by bending it in three pieces and then welding them together.

To be honest Dave - I usually just give the fabricator details of the shoes we require and let them work it out for themselves, but this one is way more complicated than usual.

We have never had one made like this, they are usually at 90 degrees to the glass beams and support a single beam.

The fabricator says he can make this one up from the individual pieces if I want him to, but I am intrigued to see if I can give him the developed shape which he says he would also be interested in.

You should be able to work out the development for the piece. What kind of metal are you planning to use? Let me think on it a little as my first cup of coffee gets absorbed.

I am thinking 3mm stainless :+1:

1 Like

Its Beam Shoe E in this overview. You can see most of the shoes are pretty straightforward. We don’t usually do the beam into a corner.

Metalwork.pdf (769.4 KB)

That adds a level of complexity, doesn’t it?

I assume the fabricator is bending the other parts in stainless, too. Do you know what the inside radius of those bends is? With that info and the k-factor for stainless steel we can work out the neutral axis in the metal and from there, develop the parts accurately.

Thank you Dave.

For what it’s worth we usually use 5mm mild steel for our shoes which we galvanise, then powder coat, but as this is a very lightly loaded shoe, we went for 3mm stainless because it has to fit in the silicon joint between the roof panels and the glass beam. For our standard shoes the various facets are laser cut so usually no bending required.

I would assume the bending axis to be central or thereabouts for this task which will be fine. We have a 10mm silicon joint between the shoe and the glass beam so super accuracy isn’t really necessary although like you I always try to make things as spot on as possible. :+1:

1 Like

That certainly makes it easier, then. If you figure out the inside radius you can add 1.5mm so you ware working through the center of the part.

I would scale the model up to meters (so your material measures 3 meters thick. This will allow you to use a larger number of segments for the small radii you need to draw. Once you have the surface extracted from your shoe you could use Unwrap and Flatten to unfold it. The larger number of segments in the arcs will increase the precision of the developed (undeveloped) shape.

Here I’ve extracted the center out of the middle part of the shoe and used Unwrap and Flatten (from the Extension Warehouse) to create a flat version. And of course with that flat version it would be a simple thing to dimension in LayOut. If it’s accurate enough I guess you could even give them a full sized pattern to work from.

I opened your firms website to view some of the projects; beautiful work. For liability and safety concerns I would think consulting an engineer would a reasonable approach. The engineer could provide all the details on an approved drawing.

I looked at your question again and am now not sure whether your question is about the specifications or fabrication process. .

Here’s what I wound up with developing it in three parts and with a 3mm inside radius for the bends.

1 Like

Dave - that looks great.

Is there any chance you would share the SketchUp model with me please for me to draw those parts up in Layout?

I’ll share it as soon as I finish with my student.

Thanks for your reply and your compliment about our work. :grinning:

My question was how to get a developed shape resulting in the beam shoe geometry I had drawn.

Thank you Dave - I will install the Unwrap & Flatten plugin as well, and see if I can replicate your results. :+1:

PM sent with the SKP file.

1 Like

Thank you VERY much for your help Dave, but this is so difficult for me to get right.

I think I may take the easier way out and draw it with welded facets.

This is one I messed up earlier :wink:

You’re quite welcome.

What part is difficult? Would it help if we talk through it?

I think I am just about there now Dave - I think I will nail it after a good night’s sleep: :+1:

1 Like