The Craftmans Shop > Radio Control Models

Hot Wire Foam Cutter

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dsquire:
Bernd

The temperature and the speed of the hot wire is the most important thing. In theory, the hotter the wire the faster the cut. The idea is that the wire does not cut the foam, it just melts it when it gets close to it and when it cools pulls back to each side and is more dense at the 2 cut surfaces. In theory the wire should not even touch the foam. It just gets close to it and melts the foam as it goes. Too fast and the wire hits the foam before it melts it. Too slow and it melts too much causing an uneven cut and possible closing up behind the wire. :lol: :lol:

This is why the temperature and the speed are so important. The best thing that one can do is practice, practice and some more practice. Now having got that all straight, it is different cutting through 2" thick foam then it is to cut an airfoil shape 30" long. Did I say more practice. :bang: :bang: :bang:

All that styrofoam and blue or pink foam that you see out on garbage pickup day, take it home with you. It can be cut up into useful pieces once you get the hang of it and until then is cheap for practice. :poke:

Some place on one of my computers I think I have alink to some hot wire information. If I can find it I will post it up here for you. :coffee:


Links added:

Here are a couple of links that may give you a few ideas. Also have some CNC controled hot wire cutter links if you are interesterd.

http://www.rcgroups.com/forums/showthread.php?t=628704&pp=30

http://www.8linx.com/

http://www.utahflyers.org/index.php?option=com_content&task=view&id=37&Itemid=33


more links added 2009-09-30

bit of foam cutting and lots of metal casting info
http://www.abymc.com/

commercial foam cutting machines
http://www.foamlinx.com/

Foam cutting power supply
http://nsrca.us/all/building/65-powersupply.html

 
Cheers  :beer:

Don

added links September 29, 2009, 10:39:06 pm
added links September 30, 2009, 12:13:06 pm

Bernd:
Don,

Ain't that the truth, pratice, practice, practice, repeat as needed.  :D

I have a bunch of foam from when they built the house, so don't need to dumspter dive just yet. :)

What is the best glue for gluing two pieces together. I've tried several products. The spray adhesive seemed to work the best. I then need to cover with fiberglass. I did a test piece with "Atomotive Fiberglass Resin", "Finish Coat" and succeeded to melt the foam. I guess there's several different resins out there. One of them must be compatible with the foam? Any idea's? Thanks.

Bernd

Edited: Yeh, add as many links as you can find. Would be nice to get them all together in one place.

dsquire:
Bernd

I have always used a slow setting epoxy when joining foam. I have also used a water based contact cement to glue two sheets together or to add a veneer covering. Atomotive Fiberglass Resin will attack most foam so must be avoided. If you want to cover foam with fiberglass cloth for strength then I would check out West Systems Epoxy. You can adjust the working times and it is one of the safer epoxies to use if you have adequate ventilation. Here is their link.
http://www.westsystem.com/ss/

I have never used it personallly but have followed a lot of articles that used it and read up on it quite a bit. It is the epoxy that I would be using if I needed a quart or more or was building a mould and parts. From everything that I have seen they seem to have an excellent reputation in the boat building community.

I also added a few more links earlier today in the above post. I figured that way they would all be together instead of spread out.

This afternoon while house cleaning I came accross some extra foam so we loaded up my delivery mans' vehicle and I gave him direction on how to get to your place so please keep an eye out for him. If there is more than there than what you can use, maybe you can give him directions to Andys' place and he can have the rest.


Cheers  :beer:

Don

Bernd:
Don,

After checking those links you posted I've gotten a bit smarter about all that's been talked about. The Utah Fleyers had the best info on building hot wire cutters. Didn't know that many kinds exsisted.

Also remembered from my days on a hovercraft forum. They taked about the West System. I checked out the prices and downloaded the price sheet. Looks like close to $75 for the intial setup. I think I'm going to try that out. There are several places close by that sell the stuff.

I think I've come to a final design on my rescue boat. I built one foam pontoon to try out some ideas. Looks like I'm going to go with two electric motors using airplane props to push it. Reason being is nothing can get caught, like sea weed, on the prop or rudder. Simple 2 channel radio and a couple of 6 volt batteries for the motors.

I see some foam I can use on that delivery guy. Then I'll send him to Andy.  :lol:

BTW, those links are great.

Bernd

Stefan Pynappels:
I built a very simple hot wire cutter when I worked as a lab tech in a college and I was asked to come up with a way of cutting polystyrene sheets abot 30mm thick into jigsaw like shapes which were supposed to simulate enzymes locking together or something.

2 thin wooden beams on either end of a pivot block with screws in the ends to connect the nichrome wire to. There was only 60mm of wire, but the throat of the cutter was about 600mm. I used a variable power pack from the lab to power it, and at the end of cutting out 400 shapes, I think I got the knack of adjusting speed and current to get clean cuts. Still hate the smell of it though..... and I think they still use my ridiculously simple bit of kit now.

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