tunnel baracing

[cerhai]

the season has come to an end and its time to look the sled over, right away I see some tunnel braces that I want to replace, looked in to the van amberg braces at a hefty price of $230 I will pass, so decided to make my own, after looking at a bunch of different designs one question rose to my mind,
why do most braces have cutouts? is the brace stronger that way or a solid fish plate stronger? here is the VA brace notice all the triangles cut out, is it just for weight or is it more structurally sound that way

 

[Sheetmetalfab]

For looks.

And to justify the price.

Hammer the wrinkles flat.

Cut your own braces out of aluminum with a jigsaw.
Smooth them with a palm sander.
Get them powdercoated locally for $30-$50.

 

[05rmksteve]

The fire n ice braces do not have cut outs and are $ 145.00.

 

[cerhai]

For looks.

And to justify the price.

Hammer the wrinkles flat.

Cut your own braces out of aluminum with a jigsaw.
Smooth them with a palm sander.
Get them powdercoated locally for $30-$50.

I have done my own plates before, my old rev was all redone with homemade bracing, Its a little easier for me than the average weekend gearhead, I have a retired friend with a full set up machine shop in his backyard shop everything I need to make these. all he asks is to pay for the materials.

 

[BigBlueEdge]

Cutouts do not add any strength. They also don't weaken the part if done correctly based on sound mechanical engineering principles. Take one of those brace shape you posted a pic of. If there were no cutouts it would be as strong as that particular piece of steel (or alum?) allows due to its metal properties. But there are parts of that flat piece that don't add anything to the strength because there are no moments of force being applied to them. Those 'cutout' pieces can be removed to save weight. Removing them doesn't weaken it. So you get less weight with full strength if done correctly. You could also take it a step further and remove more material and weaken it a little bit but still have 'enough' support, while saving even more weight. It's a balancing act.

This is the same principle as a standard truss or bridge that is made up of beams. If you transfer the forces through the metal structure correctly you don't have to have a solid structure.

Rob