"Insulation Foam hills? Tips, cutting - hot knife?" Topic

I'm planning to make a bunch of terrain in 1" thick and 2" think blue/green/pink insulation foam – the kind that snaps if you bend it, very common for terrain making.

I'm looking for both a specific recommendation on cutting it, such as a hot knife to purchase or other suitable means, and any tips people have for cutting the foam.

I was thinking that a jig-saw type of blade might do it, but would probably create loads of foam bits to dispose of.

Thanks!

A hot wire cutter is indeed your best friend with foam board. Mine is decades old from the Armory, but a web search will give you many to choose from (I see that Woodland Scenics among others makes one).

For large-scale gross shaping, rather than sawing I recommend cutting with box cutter or long X-acto blade.

You can further shape and smooth cuts with sandpaper. When it comes time to paint, I have had good luck with first applying a coat of artist's gesso, which gives a good toothy surface for successive layers of paint and seems to eliminate any need for a second coat to ensure opacity.

Get youself a Proxxon Hot Wire Cutter. While you wait upon delivery, take some time to research it on YouTube. Shifting Lands is a German vendor who makes phenomenal accessories for it, too many, too complicated to describe what they can achieve.

You can make a few of the tools, yourself, to save money. The circle cutter is the simplest to build. The tool for making precise, straight cuts, is more work to build, and it will likely be worth your money to buy it outright. The other accessories allow you to build onion domes (Russian cathedral types), and many other shapes, all carved out of foam insulation.

I bought mine, a few years ago. I was given a 7' length, 5"-square, of open cell foam packing material by a friend. I carved it up with my Proxxon, and I made 50+ foam hills (second image; uncovered foam pieces), which I covered with the same indoor/outdoor TeeTime green carpet that I cover my table with, for mini's games. They are not realistic looking, but they are eminently playable. I attached the carpet strips and pieces using Low Temperature Hot Glue -- fast, efficient, and easy; the Low Temperature Glue did not melt the foam. The hills perfectly match my table surface.

Here is an image of some modular, cavern wall sections I made out of pink foam, using my Proxxon. I angled the cutting wire, then I free-hand pushed the foam pieces through it, wiggling it as I went. I wanted a natural, rolling cut, as if carved by water, over time. It is not realistic, but it works for me. I painted the pieces with house paint (latex), then I brushed on The Dip Technique, for shadowing (Minwax urethane stain will dissolve unpainted foam, so make certain to apply it only to painted foam sections…). Very simple, very fast, with acceptable (to me) results. Just some ideas for you to consider. I place them end-to-end, to form caverns, for FRPG's and fantasy mini's games (BattleSystem Skirmish).

I'm old-school for terrain and painting, but the Proxxon gave me something I've desired for decades. I love that machine, I do not regret spending the money, at all. Worth every penny, Baby! Cheers!

Some good suggestions here. I have a couple of things…a hand held hot wire cutter…battery powered…between wire and the back is about 6-8"…I also have a hit saw…batteries in the handle and blade is serrated about 9" in length….could not tell you where I got them.

I also use a a battery powered hot wire cutter that I got at a model railroad show many, many years ago. I also use regular matte acrylic house paint and can get a good cover with just one coat.

As an example, I made these 4" hex hills using the cutter and a cardboard template.

In December 2020 I cut a large number of Chrismons for the outdoor cross at our church. We used them again this past December.

Jim

P.S. That's a 15mm Memoir 44 game.

I use a set of hot wire tools from the Foam Factory, they have a large range.

Uh Colonel, there seems to be a madman in a blue box on the battlefield…

link

Cheaper floral battery operated foam cutter and serrated kitchen knife are my two tools

Spray after with water based paint to do basecoat then scenic touches

Dr. Who isn't mad, he's just slightly deranged.

Jim

First off , if you get a hotwire cutter don't uses it in a enclosed space. It make a Poisonous gas.

Foam can easily be cut with a streak knife, Small blade cutter, hand saw and worked on with a rasp/file. If you want really straight cut uses a table saw.

Over time, the edges of hills tend to chip off in places, so before painting I always give them a good coat of Mod Podge. It's best to paint the Mod Podge over the edge and then an inch or two on the underside. Haven't had one chip yet.

I use a very, very sharp kitchen knife with a very stiff blade. It cuts it fine. I seal the lot with two coats of undiluted PVA to protect it from damage and stiffen it up.

I very much like using a wand style hot wire knife to cut hills and shape the edges at an angle. Something like this should work: link

When using a hot wire, make sure it is well ventilated. Those fumes are toxic.

Also, to make the foam super strong, coat in 2-3 layers of PVA and sand. I do the top and bottom to completely seal the foam. A couple coats of hobby acrylic paint and it's ready for details. Don't use aerosol on foam as it could melt the foam.

If you do use a saw or knife or rasp on the foam, wear a dust mask and safety goggles. The dust is a real pain in the butt.

Lots of good advice so far.

But it really be more a matter of knowing what you want to do than any one tools does it all.

I have played around with most (if not all) the tools for working form. If you want exact shapes, you need a table style wire cutter, and Proxxon is the best, but also costs $. USD

If you just want hill shapes, skip cutters altogether. Just snap your foam into something a bit bigger, then melt the sides to shape. You can get slopes, cliffs, even rolling hills. I like heat for melting, but some folks like chemicals. But let use stick to heat for now. Most anything that gets too hot to touch will work, old flatiron, soldering iron, hair curling iron, also hot air sources, like old hair dryers, heat guns, butane torches, even cigarette lighters. Open flame is clearly a danger, but you need a way to snuff a flame no maker what heat source you use. Place the snapped off foam with a side you want down against some flat surface like a stone counter top, or sheet of metal, and melt the edge back with the heat source. The foam collapses into itself making, often, natural looking shapes. The flat surface soaks up heat leaving the bottom level.

It is shocking that I can not find a video of this, but here are two which can give you some idea. Both working with the even cheaper bead-board type foam.
First a heat gun:
YouTube link
This one, they are not making anything, just melting stuff, but you can get some idea.

The next is using a candle flame, the actual melting starts about 2:30 into it.
YouTube link

I got spoiled when I won some carved foam hills at a con some years back. They were glued to a thin, beveled edge, plywood base, which gave them rigidity and weight, which keeps them from sliding around the table.
I've copied the technique but haven't mastered it. Probably the difference between a professional setup and making do with tools not designed for the job.

I second the vote on the Proxxon 115e link , best hundred bucks I ever spent on a tool. I have been making things for years without a hitch. It works like a table saw or a jig saw and has tons of after market accessories. Just a few of the things I have made:

Very impressive, very inspiring, Anton Ryzbak! Thanks for sharing! Cheers!

Thanks Sgt Slag, Lots more shenanigans here link

@Dyehard
Do you have any pics? I never thought of that!
When the heat is close [say, hot hair dryer] does it make toxic fumes, or are they "contained" by the insulation foam melting?

I have some small scales I work in, 10mm and 6mm and even some 15mm, that I think that would work well with.

For the larger 30-54mm stuff, I am ok with more of a "toy soldier" look that is less "natural".

But certainly intrigueing.

I was also thinking about the wands that Cormac Mac Art mentions and links. In fact, that was my #1 idea from the evil A-zon before I posted!

I do not have any photos of my own right now, and stuff packed away. But I did find this example on the web:

I would always assume that something unpleasant will come off or out of melting foam, best done outside. But it would be a function of your tolerance and the size of the project. Heat alone should just collapse the foam structure, but who knows what the puffing agent was. A side benefit is it forms a "crust" of more solid plastic, so stronger and tougher.

I know by posting I'm resurrecting this wonderful and very informative chain/posting – that's part of my purpose as I didn't want it all to get too buried in the Boards. But my main goal is to thank each and everyone of you for posting your material and tools ideas. I found it VERY entertaining and helpful and the varied entries sparked my own interest and zeal to try some things – plus I've purchased many new tools both mentioned here – foam hot wire cutter, foam board, adhesive, and on and on. I also found beaucoup terrain, material and tool demos on UTube as adjuncts and hints.
So, and to all, thank you and keep up the very good work and motivations.
(Tom,,,,,don't know if you are still a ‘hostage' in Europe, but you need to write a book someday of all your experiences and knowledge in the hobby world.)
(Anton, truly inspiring stuff you make. Maybe not the ironclads however,,,,,ha ha.)
Toby Barrett