Rail Construction

I realize that this has nothing to do with boat construction. But I am hoping to tap into the wisdom here.

I need to build about 40 fiberglass posts to house some equipment for a project I am working on. The inner dimensions for the C channel would need to be about 3" x 6" and each section would be about 40" tall. My plan would be to put a 1" lip on the open side of the C and then screw a fiberglass sheet onto the open side to seal the unit.

20 of the posts will contain 6 pieces of equipment, mounted to the side weighing about 4-5 lbs. The other 20 posts will have less than 1 lb of equipment inside.

The pieces will be mounted vertically with the heavier sections on the bottom and the lighter section on a hinge mounted above. So overall height will be about 80".

As this will be 80" x 3" x 6" and there will be 20 posts, that need to be rigid enough to not flex once set up. The most they will be exposed too is an occasional bump. The heaviest items will be in the bottom of the first post and mounted into a base.

II was think of going with a gel coat, 1 1/2 oz CSM, then 3 layers of 6oz cloth laid at 45 degrees. Does that seem like it would be strong enough for the C channel. The cover for the C channel will be same lay up. I prefer to keep the structure hollow, if possible, but if need be I could add end caps on to stiffen.

Thanks in advance for your replies.

 

Welcome to the forum.

It might be more helpful if you could describe what this is for, maybe posting a simple sketch. I'd be inclined to use fewer layers of material and skip the gelcoat. In any case a laminate this thin, will be pretty flexible.

I also think 1/4" plywood would be easier and faster, if a little tedious doing 40 of them. You could run the 4x8 sheets through a table saw, ripped to the widths you need, butt joint the corners, maybe a fillet on the inside if you need the strength. Painted with house paint, who'd know?

On the other hand, if you need an inert material, consider the 'glass sheets you can get at Lowe's/Depot, found in the wall paneling section. These too come in 4x8 sheets and it's about 3/16" thick and a pure polyester and 'glass sheet. It can be cut, just like plywood, glued to shape and you're done. No laminating, no mold, just gluing strips of 'glass panels together into 3"x6" tubes.

 

Thank you for the reply.

Yes, I agree it could be done easier in 1/4" ply. I was hoping to save on the weight, with plywood I am guessing I would add another 100 lbs over glass. The "glass" sheets I was looking to avoid, #1 due to price, #2 prefer to keep the light out.

What I am building is a tower to house computer components for a 3D scanner. Two different power supplies, 5 micro computer boards with cameras, LED light strips, Network Switch and Power Strip. With 20 towers I am capable of scanning 360 degrees of a life size object in a couple seconds.

I evaluated vinyl railing, but the ribbing inside would need to be removed where the components go. In the end it would be 10 times harder to fabricate than building from scratch.

As this is a prototype that I am building, I will likely go the route you suggested on plywood.

Thank you for your reply.

 

There are several companies, like Dynaform, that sell fiberglass channel, I-beams, etc.

 

Actually, plywood will be lighter for the same stiffness and strength.

Look into the prefab 'glass panels at the big box stores. You can also buy prefab 'glass panels of various thickness wholesale. Conversely, you might consider making your own panels or possibly "L" shapes, to eliminate 2 bond lines. It takes quite a bit of 'glass to equal 1/4" plywood's strength and stiffness, usually resulting in a heavier end result.

 

Can you use aluminum sections?

 

Sheet aluminum could be easily bent and glued or welded on a single seam. Not cheap, but fast and inert.