Project Capri Hard Top: How do I bend the top?

[Mark42]

Been messing around with the side and top pannels I cut from foam. I think the side pannels are a little too tall, and the top should be curved (as other members previously suggested). I'd like to cut 3" off the height of the side pannels, and put a 3" bow in the top. This is what it looks like now:

So here is the top. Its leaning against the Mountianeer so you can get a feel for its size. The trailing 6" edge at the bottom needs to be cut off, just havent done it yet. The point at the tip is the center of the V shaped windshield.

So what is a good way to bend this 1.5" thick foam? Its fairly rigid, I can bend it about 2" by hand, but more than that and I'm afraid it might snap. Also, bending like that just bows it in the very center, not evenly.

I can take a razor knife and make 3/4" deep slices on the top side (showing) every 3 inches or so. I'm sure that will let it bow nicely, some strings can be used to hold the bow while two "D" braces are glued on from the underside (one near the front, one near the rear). I could fill the slices with epoxy putty so it will tend to hold its shape and not close up (go flat again) before I get the epoxy and glass on it.

I know it will shrink in width an inch or so from bowing, but not enough to be a problem. I made it plenty wide enough.

Any other ideas or suggestions?

 

[superpop]

Re: Project Capri Hard Top: How do I bend the top?

I am sure you know this but while it fits in your garage now, you will not be able to get it out once that top is attached. Is that why you want to cut it down a bit?

 

[superpop]

Re: Project Capri Hard Top: How do I bend the top?

Also, you may want to consider some windows on the sides or you are going to have some monster size blind spots on either side.

 

[Mark42]

Re: Project Capri Hard Top: How do I bend the top?

I am sure you know this but while it fits in your garage now, you will not be able to get it out once that top is attached. Is that why you want to cut it down a bit?

Yeah, next project is to raise the ceiling of the garage.


Once the top is done (and it is removeable) I won't have to put it in the garage. It will be covered outside.

I like the headroom in the center, so I want to keep it. By cutting down the sides, it will look more proportional and have a little less area for wind to push against making manuvers easier. Bowing the top 3" will keep the same headroom in the center. The cross braces would be needed even if the top is not bowed. And snow buildup in winter won't bend the bowed top like it could a flat top.

The roof pannel has to be finished before I can start making and fitting the windshield frames.

I don't want to go overboard engeneering this top, but I don't want it to fold up in the wind or under snow weight either.

 

[Mark42]

Re: Project Capri Hard Top: How do I bend the top?

Also, you may want to consider some windows on the sides or you are going to have some monster size blind spots on either side.

Just haven't cut them out yet. Thats pending the finished side pannel height. Take the link in my signature to see the photoshop pictures of the finished product.

 

[redfury]

Re: Project Capri Hard Top: How do I bend the top?

I'd say your best bet is to either cut slices down the middle of it and then fill them in, or....

scrap that and buy yourself a few thinner slices of the same stuff and laminate the foam into the shape you want and trim off the excess. You can bend the thinner foam the way you want to by making a quick jig out of some wood, and then layer the foam sheets on top of each other, bonding in between with whatever adhesive works best for that pink stuff. You'll end up with a stronger top, and get the shape you want without monkeying with the thick piece of foam.

You may even find yourself using furring strips along the width of it to create the bow and lay the foam over that like an old cedar strip canoe. Couple of ways you can do this and get excellent results.

 

[Dan Schmidt]

Re: Project Capri Hard Top: How do I bend the top?

Polystyrene foam is brittle and cannot be bent effectively without uniform heat.

 

[TheWoodCrafter]

Re: Project Capri Hard Top: How do I bend the top?

So Mark, you are planning on using the foam board permanently for the sides and top?

 

[i386]

Re: Project Capri Hard Top: How do I bend the top?

Did you see the bending jig i made for my deck?

I scored my plywood on both sides then screwed it to the jig and filled the saw kerfs with thickened resin. Not quite the same medium as foam board but it might work.

Pics of the jig start about here.

 

[oops!]

Re: Project Capri Hard Top: How do I bend the top?

I'd say your best bet is to either cut slices down the middle of it and then fill them in, or....

scrap that and buy yourself a few thinner slices of the same stuff and laminate the foam into the shape you want and trim off the excess. You can bend the thinner foam the way you want to by making a quick jig out of some wood, and then layer the foam sheets on top of each other, bonding in between with whatever adhesive works best for that pink stuff. You'll end up with a stronger top, and get the shape you want without monkeying with the thick piece of foam.

You may even find yourself using furring strips along the width of it to create the bow and lay the foam over that like an old cedar strip canoe. Couple of ways you can do this and get excellent results.

Polystyrene foam is brittle and cannot be bent effectively without uniform heat.

gotta agree mark......unless you score the back side of the foam....it will be really hard to bend.....you might want to think about thin plywood, or expanding foam, and carve the shape you want....either way its gotta be glassed ....so you just need the shape

 

[Mark42]

Re: Project Capri Hard Top: How do I bend the top?

I'll give slicing it a try. If it doesn't work, then I'll try 1/4" ply.