Foam suitable for vacuum former ?

[flanajb]

Having not had much joy with my timber former for vacuum pressing some curves, I think I would be better off making the former out of solid foam. This will also make the former a lot lighter as I struggled to lift the one I spent nearly a day making.

If solid foam will suffice, anyone able to tell me where I can get hold of a piece 60cm*60cm ?

Thanks

 

[Steve Maskery]

Insulation foam, the pink stuff from B&Q, is a very good material for this kind of application. It a few years since I bought any, but, IIRC, I got a man-size pack of 4 sheets for about £20.
Cutting it is the problem. If you have a controllable power source you can cut it with a hot wire. Otherwise, it's a case of bandsawing it and collecting a lot of fine pink dust (for a long time to come!).
S

 

[flanajb]

Insulation foam, the pink stuff from B&Q, is a very good material for this kind of application. It a few years since I bought any, but, IIRC, I got a man-size pack of 4 sheets for about £20.
Cutting it is the problem. If you have a controllable power source you can cut it with a hot wire. Otherwise, it's a case of bandsawing it and collecting a lot of fine pink dust (for a long time to come!).
S

Thanks Steve. The plan is to clamp it between 2 formers one at each end, and then use a piece of timber with a piece of coarse sandpaper glued to it to form the curve ?

I will also look into making a hot wire

 

[Steve Maskery]

The plan is to clamp it between 2 formers one at each end, and then use a piece of timber with a piece of coarse sandpaper glued to it to form the curve ?

That's exactly what I did originally. It's jolly hard work. I'd recommend making it up in vertical layers, like a loaf that's been sliced the wrong way. You can hot melt it to a template and then use a notched fence on your BS. The slices are then stuck together with a building adhesive. The results were much better, as well as being less tedious.

S

 

[flanajb]

The plan is to clamp it between 2 formers one at each end, and then use a piece of timber with a piece of coarse sandpaper glued to it to form the curve ?

That's exactly what I did originally. It's jolly hard work. I'd recommend making it up in vertical layers, like a loaf that's been sliced the wrong way. You can hot melt it to a template and then use a notched fence on your BS. The slices are then stuck together with a building adhesive. The results were much better, as well as being less tedious.

S

Thanks. That makes sense.

I think this has to be the way to go when making a large former. Timber ones rapidly get so heavy with all the bracing, that you struggle to lift it.

Just a couple of questions.

1. Does the foam collapse at all under vacuum or does it remain stable ?

2. If I buy 35mm thick sheets, could I template them using a router ?

Thanks

 

[Steve Maskery]

I didn't have any trouble with it collapsing. It is quite dense-structured. I covered the top with a thin layer of backing-board and varnished it so that glue didn't stick. There was no collapsing.

If you use a router, keep the speed right down. You might get melting problems. I don't know, never done that, but I'd see that as a risk.
S

 

[flanajb]

I didn't have any trouble with it collapsing. It is quite dense-structured. I covered the top with a thin layer of backing-board and varnished it so that glue didn't stick. There was no collapsing.

If you use a router, keep the speed right down. You might get melting problems. I don't know, never done that, but I'd see that as a risk.
S

Given your experience, would you always make your former out of foam. The reason I ask, is that in my other post, someone suggested making the former out of mdf, but having 3 or 4 ribs, followed by a solid former. This also sounds like it has potential, but I imagine it is still going to be heavy. I suppose the only way to work it out is to weigh one of the solid former, make a rib and then calculate the total weight of the finished article.

There are pros and cons with both.

Foam
Nice and light, but has the downside of being difficult to shape, unless you have the right tools

MDF
Finished former will be heavy, but can use template and router to ensure a very accurate former.

Decisions, decisions :duno:

 

[Steve Maskery]

Foam every time.
MDF ones are very heavy and the hollow structure does not give uniform support. You can easily get a laminate that has the rib shadows in its finish. DAMHIKT.
Foam, foam, foam.
S

 

[flanajb]

Foam every time.
MDF ones are very heavy and the hollow structure does not give uniform support. You can easily get a laminate that has the rib shadows in its finish. DAMHIKT.
Foam, foam, foam.
S

Steve, your the Man! Foam it is. Thanks