Trailer lid truss design ideas - Looking for feedback ii

[Woods]

I've designed a roof truss and am looking for feedback from you guys.

The trusses will have four different hole types in it.

First hole type does not show in the picture. These holes will be used for rivet or plug welds. These will easy assembly to the side caps and top sheet.

Second hole type are the triangles. These are designed to allow a webbing strap to run through them, and support the strap with a flat surface.

Third hole is a the large circles. You can't tell from the pic, but these are ovals. They are sized to allow a shock cord end to run through them.

Fourth hold type are the medium size circles. These are for hooking the shock cord ends.

I haven't been able to think of anything else that should be designed into the truss. I was think that those who have been doing thes longer than I, may have additional ideas. Suggestions would be greatly appreciated.

 

[Woods]

Originally Posted by Saiyan66
Looks like a decent design to me. I would be interested in what material you are planning on using and it's thickness. Also some dimensions on the span and height of the truss would be good. Are you planning on having your cut-outs water jet cut or plasma? All these details will help us give you more feedback. FWIW I have more experience on the manufacturing/fabrication end of things than on the CAD side.

.080 thick aluminum.

Parts are laser cut.

Overall width is 48". Height is 7.25. Span across the middles section is 35.3"

The lid is pretty thick at .125" The end caps will be .080. Currently my lid is unsupported at an overall width of 48" and I can stand on it. I figure the trusses will add some rigidity and lashing points for storage.

Cross supports (square tubing that go in the square cutouts that you see) are 1.25" on the base and 1" for the tops.

Nuther pic - flat sheet veiw, shows rivet / plug weld holes before tabs are formed:

 

[Woods]

Sorry bout the dup thread guys. I tried to delete a post and it deleted the whole thread.

 

[Titanpat57]

That looks pretty, damn slick.

I had some parts cut out by a lasercutter, and it was kind of pricey..

 

[Woods]

Yup - 5 of them will be a bit over $200

That looks pretty, damn slick.

I had some parts cut out by a lasercutter, and it was kind of pricey..

 

[madmanvillain]

Are the holes going to be dimpled or just cut out? If they dont get dimpled it will cause a chaffing issue on the webbing and shock cord. And no body likes chaffing.

 

[78Bronco]

Are the holes going to be dimpled or just cut out? If they dont get dimpled it will cause a chaffing issue on the webbing and shock cord. And no body likes chaffing.

Dimpled with all round holes. Scrap the triangles.

 

[Woods]

Just cut out. I'd have to smooth out the edges to prevent chaffing.

Are the holes going to be dimpled or just cut out? If they dont get dimpled it will cause a chaffing issue on the webbing and shock cord. And no body likes chaffing.

 

[Woods]

I don't know that I can do dimples. Will have to check with my shop. Scrap the triangles because of aesthetics, or they just are not usable?

Dimpled with all round holes. Scrap the triangles.

 

[jamm]

I don't know that I can do dimples. Will have to check with my shop. Scrap the triangles because of aesthetics, or they just are not usable?

What were you planning to use straps for? Is doesn't look like there is much room between the bottom of the triangle and the lid. Are you looking at something being that heavy that the cords wouldn't do the job?

I like the idea but I would scrape the triangles and replace with circles or ovals. To save costs just put 1 line of the small circles across the top of the truss to hook into.

 

[Woods]

You're right, cords would be plenty strong.

I was thinking to use a ratchet strap through the triangles. The ends would hook to each end of the lid. Loose I could load folding chairs tables etc. Just tighten it up when done. I'm on the fence on how easy this would be to do with multiple chairs tables... Probably wouldn't be easy and easy is what I'm looking for. This is why I posted here. You guys have me thinking this through.

There isn't any cost savings by having less cutouts.

What were you planning to use straps for? Is doesn't look like there is much room between the bottom of the triangle and the lid. Are you looking at something being that heavy that the cords wouldn't do the job?

I like the idea but I would scrape the triangles and replace with circles or ovals. To save costs just put 1 line of the small circles across the top of the truss to hook into.

 

[Pikeman]

I am surprised there isnt a cost saving with fewer cut-outs. Anytime I have had something laser cut I have been told that the charge goes up for each new penetration wether it is a 1/4 inch or a 48 inch cut it is the same because the wear happens when they make the initial perferation.

 

[Woods]

that may be correct. The shop that is doing this work, does a lot of work for me. This is a small side project that they are doing as a favor (though I pay).

I am surprised there isnt a cost saving with fewer cut-outs. Anytime I have had something laser cut I have been told that the charge goes up for each new penetration wether it is a 1/4 inch or a 48 inch cut it is the same because the wear happens when they make the initial perferation.

 

[78Bronco]

I don't know that I can do dimples. Will have to check with my shop. Scrap the triangles because of aesthetics, or they just are not usable?

I would just run dimpled holes down the center. It will be cheaper to have cut and you might add a pound to each piece.