View Full Version : Hotwire Foam
11-21-2005, 06:15 AM
CNC hotwire. I don't even want to know what that machine cost :p
I'm so sick of making rubber molds. Direct built, hard coated foam is looking better and better every day.
11-21-2005, 07:47 AM
Aside from the initial price of the equipment, consider the cost of those huge foam blocks, as well as the fact that much of what a machine like this does is limited to rather rough finished shapes that can't have severe undercutting. A rapid prototyping machine, which can create literally any shape by depositing layers of material to build up the form is superior, where that's concerned. The disadvantage is that you are limited to small sizes, as opposed to the larger sizes that can be done via hotwire CNC. This machine is great for stock shapes like fluted tapered columns, for TV and movie sets, or 3D lettering for signage, etc., but it has rather limited application for serious fine art sculpture....unless you're a minimalist. Better for sculpture, if you're going the CNC route, is a 5-axis CNC router, which can do things a hotwire cutter can't. http://www.danielsengraving.com/foam/a-6.shtml. But, bear in mind that, with either method, there is still the requirement for a lot of hand finishing. Even with a 5-axis router, there will be areas the machine just cannot do and these will need to be carved further, by hand, and smoothed by hand. Nothing approaching the level of finish shown in these gallery photos comes out of the machine without additional hand finishing.
11-21-2005, 09:30 AM
Hi, Yeah, I thought it'd be fun to carve some foam and then coat it with fiberglas. Well, Trymer board is, I think the only foam that can be directly covered with fiberglas, and it ain't cheap!
Some guy tried to sell me a 2'x4'x8' for about a grand and all I wanted was a small piece to try and see if I liked it.
All other foam products melt when they come in contact with the fiberglas resin unless they're coated with something.
I may try some foam sheets from the lumberyard, blue board or something, glue them together with who knows what? Carve it, coat it with latex paint or acrylic polymer emulsion and try fiberglas.
I haven't done any of this so if my info is incorrect, please set me straight. Thanx!
Have a great day,
11-21-2005, 10:57 AM
Actually, any polyurethane can be directly coated with polyester resin without damage to the foam. It is polystyrene (Styrofoam) that polyester resin dissolves. Even this can be prevented by the use of a barrier coat of some kind, applied under the fiberglass.
That was definitely overpriced. Check this out: http://www.aircraftspruce.com/catalog/cmpages/lastafoam.php
11-21-2005, 12:47 PM
speacking of which:
I think I want to try hotwirecarving of foamboard glue-ups
when I've carved foam glueups , it is with knives and saws and grinders and gouges and hooked blades(made out of old bandsaw blades with reshaped edges) and is a really terrible mess when I'm done, and leaves me vaccuuming bits and pieces for weeks-----some of the stuff gets a charge and flies and sticks to anything it can find with an opposit charge
so, I was thinking of making a hotknife but ain't researched it yet
plannin to make fake foam rocks and other decorations and rough figures painted and/or covered in stucco for the greenhouse desplays
11-21-2005, 01:24 PM
I'm using the same process, myself; i.e., carving blocks of foam by hand, which I've assembled from glued sheets. I'm using a 1 lb. Styrofoam, though, which carves very easily, and I'm using acrylic modeling paste (acrylic binder with powdered white marble) as the shell material, which I then paint and seal with spray acrylic. This works fine for indoor display.
As for tools, all I use is a drywall saw and a small surform.
Where do you do your carving? I do mine in the garage, so cleaning up means just sweeping the floor when I'm done.
For foam rocks, you might try a technique I picked up from sculptor Don Frost. He uses pourable polyurethane foam kits and pours them into a plastic trash bag. This results in freeform blobs that look sort of rock-like. The it's just a matter of finishing.
11-21-2005, 02:03 PM
homemade hot wire tools.....
11-23-2005, 07:37 PM
I got everything save the Nichrome Wire
thinking it's gonna be a bit easier than I had feared, and I'm gonna try shaping and smoking some of the old bandsaw blades and other steel wire on the shelves while asking around for the nichrome (nichrome=nickle chrome and steel?)
11-24-2005, 09:39 AM
Personally, I tend to just use a wire brush and sand paper. A hot wire comes in useful for cutting, but I really just need a wire brush for shaping.
11-24-2005, 10:48 AM
Nichrome wire is used for heating eliments in kilns.
Take a look on e-bay. There's a lot for sale there.
Try an old toaster? http://www.toaster.org/works.html
04-10-2007, 04:07 PM
I webmaster the www.hotwiredirect.com website. I noticed a few people coming to our site from this thread. I may be able to give you more information regarding hotwire foam cutting and eps foam suppliers.
First of all, the expanded polystyrene (EPS) foam is not very pricey, a block that measures about 4'x4'x8' of 1 pound per cubic foot density is about $200. 2 pound foam is double that amount. You may be able to get recycled/regrind for a little less. These prices are as of today's date and vary with petroleum prices, i.e. they were half this amount only 7 years ago. For a rather comprehensive list of foam suppliers in your area visit:
There is also a link from there to international block molders.
Regarding the prices of the hotwire cutting tools, we offer a hot knife for $259 this includes a basic blade and nice carrying bag. We also have nichrome wire, power units, and computer controlled equipment.
We have aided the nearby Walla Walla Foundry on one project in the past. http://www.wallawallafoundry.com/digital/assembly.html
Let me know if you have any more questions: email@example.com
I hope this all helps,
04-17-2007, 12:56 AM
We specialize in cutting expanded polystyrene...it has been a long learning curve over the past 5 years but we are now capable of creating just about anything asked of us....our website outlines some of the equipment we have and shows many photos of past projects.... www.3dcustomfoam.com ...we started with hotknives and progressed to the newest technology....we use 3 axis CNC machines but have our eye on a 5 axis ...our company name is 3D Custom Foam Inc. and we are located in Burnaby B.C. Canada (several miles away from Vancouver)
04-17-2007, 08:42 AM
I may try some foam sheets from the lumberyard, blue board or something, glue them together with who knows what?
Glueing Blueboard is basic Martha Stewart grade crafting. 3 words... Hot glue gun. We do this all the time at work to form knockouts, cavities, beam pockets etc for precast foundation walls.
I havent tried it yet on blueboard.. but Smooth-on "shell shock" should be compatible as a top coat.
04-22-2007, 09:13 PM
Nichrome wire isn't usually what you want for a hot wire foam cutter that you'll use by hand (as opposed to a CNC machine).
You probably want to use inexpensive stainless steel wire in the .012" to .024" diameter range. One source is a tackle shop---stainless steel leader wire in (in the 30 to 110 lb test range). Stainless has several times the resistance of regular steel, so you can use a thicker, stronger wire and keep it really taut without burning out a reasonably-priced power supply.
You can make a good power supply from a dimmer switch or router speed control and a dumb transformer.
This thread over on rcgroups.com may be useful
And in particular this post where I compiled a lot of info about wires and power supplies, and sources for parts. (I've made several now.)
05-16-2007, 06:58 PM
I have read some of the questions regarding the use of EPS foam and CNC hot wire cutter. First, there are several manufacturers of the machines. The basic cutting is done by manually manipulating the hot wire or by feeding dxf. files via computer. This is process is mostly a 3 axis feed by which a nichrome wire will slice through the expanded poly styrene ( EPS Foam). There are several software programs that can derive the files needed, a basic ( and inexpensive) is rhino 3D by McNeel. Profile cutting is the usual output, though some hotwire machine incorporate a rotating platform which allow for 4 axis manipulation. Available machine include some of the basics by Hotwire Direct and Chroma. These machines will wire cut up to 3# EPS and most basic blue foams by Dupont. these machince retail for about $15000 To upwards of $100,000 for multple wire access. The bulk are used for manufacturing architectual elements. I would recommend finding someone with a machine and producing your own file, most pieces are cut within minutes this way.
05-17-2007, 11:57 AM
Profile cutting is the usual output, though some hotwire machine incorporate a rotating platform which allow for 4 axis manipulation. Available machine include some of the basics by Hotwire Direct and Chroma. These machines will wire cut up to 3# EPS and most basic blue foams by Dupont. these machince retail for about $15000 To upwards of $100,000 for multple wire access.
There are vastly cheaper CNC hot wire cutting machines, and kits and plans for making your own even more cheaply.
My impression is that you can make a modest-sized machine with 2-axis control of each wire end for several hundred dollars, or buy one for a very few thousand. RC modelers use them for cutting wing and fuselage cores. (Mostly profile-like cuts, but with taper and/or twist; the paths followed by the ends of the wire can be different sizes, shapes, and/or orientations, so that you get 3D shapes that interpolate linearly between two 2D shapes.)
Not my area, but there's a bunch of information on this in the hot wire foam cutting forum and other forums on www.cnczone.com.
01-06-2009, 11:17 AM
I make very affordable hand operated hot wire foam cutting tools. The Bow Cutter and Freehand Router seem to be the most popular tools among professional sculptors. You can get them from many of the sculpture supply stores, or directly from our online store. You can see them at www.hwff.com (http://www.hwff.com).
Be sure to check out the Gallery section to see some of the incredible sculptures artists have made with our tools. We also have specially formulated glue and coatings that will not dissolve the foam, or that can be used as a protective coat before fiberglassing.
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