Question about foamcore

[pacopaco]

Hi All,

Whenever I use foamcore, it is very hard to cut and the results are uneven and messy. What does everyone use to make the cuts into this stuff so that my edges end up looking nice and smooth?

[The Plastic Surgeon]

You need to cut and peel back the paper layers and then cut the foam using a very sharp scalpel or even a hot knife.

Hope that helps!

[Hephesto]

It rather depends on how thick the foamcard is. The thinner stuff can be cut pretty easily with a crafts knife. The following works quite well for me:

- draw the shape you want to cut (make certain your measurements are correct)
- use a ruler and craft knife to trace the edges and slowly work you way down into the material
- if it is a simple square shape a few deep cut will be enough to allow you to break of your part from the rest of the sheet
- once done use the same craft knife to shave of any bits of the foam that may be sticking out
- add glue, bit and some paper clips for structural purposes nd you're really to go ;)

[brominated]

In my experience with the Foam core, the hot-wire works great. Use the tip to bore a hole then drag it slowly along a straight edge. I've also found that you can make a hotwire just by putting wire on a heating element or using a lighter and dragging it along. That works great on 1/2 inch thickness foam which is what I am working with presently.

Hmm, I think a bit of clarification is in order. I call foam-core the sheet polystyrene you get for insulation materials. Thats what I'm using right now for my project. I guess there is some confusion on my part on what is foam core. Wouldn't hotwire work just fine if you slit through the card and go into the foam-board?

[Klingsor]

Are we are all talking about the same stuff?

Foamcore to me is a sheet of thin polystyrene faced with thin card on each face. It comes in 3, 5 and 10 mm thickness's though 5mm is the most common and is normally white though black and other colours can be found.

Foamcore is easily cut with a scalpel or any sharp craft knife but the blade has to be sharp and for some reason it dulls blades quite quickly. I mark out what I want to cut with a ruler and sharp pencil then cut it using a scalpel and stainless steel ruler.
I do not peel the card back unless I want to expose the polystyrene for some quick texturing, if you are happy with a flat surface just leave it be. I have found that the last box of foamcore I bought seems to have the card better bonded to the polystyreene as it is harder to remove at all, let alone neatly.

One would suspect that your blade is not sharp enough.

A hot wire cutter is superb for naked polystyrene sheet, particularity on the expanded sort as it makes a lot less mess than cutting it with a knife. For foamcore it is a bit of an irrelevance, thee is no point peeling back the card, it is difficult and messy and does no good to the surface. Stick with a scalpel, it is cheaper as well!

[Mananarepublic]

I use a real retractive blade cutter that I can set a specific length. I use a metal ruler to help me with the guidance and then I cut straight through and then along one length.

/M

[pacopaco]

Are we are all talking about the same stuff?

Foamcore to me is a sheet of thin polystyrene faced with thin card on each face. It comes in 3, 5 and 10 mm thickness's though 5mm is the most common and is normally white though black and other colours can be found.

Foamcore is easily cut with a scalpel or any sharp craft knife but the blade has to be sharp and for some reason it dulls blades quite quickly. I mark out what I want to cut with a ruler and sharp pencil then cut it using a scalpel and stainless steel ruler.
I do not peel the card back unless I want to expose the polystyrene for some quick texturing, if you are happy with a flat surface just leave it be. I have found that the last box of foamcore I bought seems to have the card better bonded to the polystyreene as it is harder to remove at all, let alone neatly.

One would suspect that your blade is not sharp enough.

A hot wire cutter is superb for naked polystyrene sheet, particularity on the expanded sort as it makes a lot less mess than cutting it with a knife. For foamcore it is a bit of an irrelevance, thee is no point peeling back the card, it is difficult and messy and does no good to the surface. Stick with a scalpel, it is cheaper as well!

It is the blade. it's just so frustrating that I can only make about three cuts, then the whole thing gets very very messy and uneven.

[Mananarepublic]

Get a silly sharp blade (a la carpet cutter) you can buy a great one @ home depot. The steel ruler helps a lot as well with making just one straight cut.

/M

[BDub]

Get yourself some of these. http://www.foamwerks.com/

[snikrot]

i use a hot knife it works very well it always gives me smooth cuts

[Bulwark]

Several years ago I read an article about using an electric carving knife to cut foam rubber. So I went out and picked one up to cut some eggcrate sheets for a case I was working on.
A few months later I was in the same position as you. I needed to cut straight lines in foamcore without tearing the paper. On a whim I tried the carving knife. It worked great! It makes a bit of a mess and you have to take the width of the blades into account, but I had perfectly straight lines in no time and without any dull hobby knife blades.
If you do this, make sure your fingers (and nothing else) is on the backside in the path of the blades. Also, cut at a steep angle, the straightness of the blades will help your lines stay straight.

[Lord Anubis]

Best advice I ever got for cutting foamcore-- never try to cut all the way through in one pass. No matter how thin it is, even if it's just the basic stuff, always make two passes. Go halfway with first one, the rest of the way with the next one.

Easier on the blades, easier on you, and super-clean results. ;)

[chromedog]

A steel ruler and a snap-off blade craft knife or a stanley knife with a fresh blade.
Whenever the surface layer starts to tear, rather than cut, I snap off to get a fresh bit/replace blade.

Clean cuts all round this way.