SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jan 17, 2005, 02:04 PM
Registered User
Martijn Kaandorp's Avatar
Joined Jun 2004
57 Posts
Foam cutting tips!!!

1.) A 5W 10 Ohms wire wound resistor is a perfect source for a
"hot cutting wire."
If you are carefull enough you can even use the original leads for mounting the "crocodile" clamps. 12V @ 1Amps will do the trick.
2.) If you need a longer wire you can also unwind the heating element of an
old dryer or an electric heater.

If anyone has tips on foam cutting just post them here!!!
Martijn Kaandorp is offline Find More Posts by Martijn Kaandorp
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 17, 2005, 02:45 PM
Registered User
Hercules, Calif
Joined Nov 2004
42 Posts
Wow and just today I was trying out some foam cutting experimate for the first time. I got the idea from a posting here somewhere several months ago and thought I would give it a try. I wanted to see if melting out servo cutouts, etc would be more accurate then just cutting or using a rotory tool. I just got a length of NICKELCHROMIUM wire, I used the yellow wire from a 14 gauge thermocouple lead extension from work. This is stiff enough to hold it's shape very well.

I threw together a somewhat crude but effective and adjustable (probe length) holder and pulled it into a 10amp variac. I found I could set the variac control to a setting where the foam would yield easy to the probe but not burn or smoke the foam. I was very suprised to see how effective, controllable and quickly one can perform very precise work using this kind of tool. I should probably use a setdown transformer between the probe and the variac as I am only a few clicks from zero on the variac for the proper setting. No more cutting and pulling or grinding for me.

Hopefully I can figure out how to post some pictures here of today's activity.

(edit: couldn't figure out how to add more then one picture even though I uploaded 3 of them?)

Lefty
Leftyretro is offline Find More Posts by Leftyretro
Last edited by Leftyretro; Jan 17, 2005 at 02:48 PM. Reason: adding pictures?
Reply With Quote
Old Jan 17, 2005, 03:57 PM
I really should be building...
UK
Joined Sep 2004
145 Posts
altho i havent done much foam cutting, when i was on the lookout for nichrome wire and couldnt find any, i tried fuse wire. this seems to work very well, and provided you can set the current for the heat accurately enough, you can get a nice cut from the trial peices i have done.
Spyda is offline Find More Posts by Spyda
Reply With Quote
Old Jan 17, 2005, 04:03 PM
I really should be building...
UK
Joined Sep 2004
145 Posts
just done a quick search on (uk) google, and came up with this:

"click here"

this is the type of fuse wire what i used, and i used an old battery pack (9.6v) and i think i used the 15amp wire. works quite well, but the pack gets warm quickly so i would have to cut quickly (as in no faffing around).
Spyda is offline Find More Posts by Spyda
Reply With Quote
Old Jan 17, 2005, 04:25 PM
Registered User
Pants's Avatar
Australia
Joined Mar 2002
428 Posts
It's very hard to say which wire will work best. I've been working professionally in the foam cutting business for a few years now and I have gone through huge amounts of wire from the smallest guage right through to fishwire tracers. Some people will prefer to cut with a wire that is very taught, others like myself prefer to cut with some slack in the wire - I think it all bears down to what substance and type of cut you're performing.

For EPP I tend to use a slightly tight, but a fair amount of give in the wire, for when cutting around corners especially in a long fuse if the epp is dense (1.9) then you will need extra amounts of amps to simply slice into it.

When I cut foam wing cores, generally speaking the same amounts of amps for epp are way to high on eps foam and the wire on eps foam should be a smaller guage as it melts a lot quicker than epp will.

Part of the big secret in cutting foam is your templates. If you have any undulations or pits where the wire can get snagged, it will exagerate the imprint into the foam - espcially in wing cores and especially on EPS. Quite often I use a feather cutting for wings and cover the edge of my templates with graphite from a pencil. Ironically the carbon helps with friction - which is crucial on the wing cores.

Other aspects you need to consider are ventilation. You will build up a resistance to foam, espcially if you're cutting over a long period of time. I am not sure which is worse EPP or EPS however a fan at the very least would be recommended and if possible an outside setting. I go about 2 hours now before I have to walk away for an hour otherwise I get headaches and itchiness on my arms, and I have been ventilation from day 1.

There's my .02 cents worth
Pants is offline Find More Posts by Pants
Reply With Quote
Old Jan 17, 2005, 05:14 PM
Registered User
Martijn Kaandorp's Avatar
Joined Jun 2004
57 Posts
Wow, 4 responses already.
The wirewound resistor wire makes really nice smooth cuts in depron.
I use a lab powersupply as a powersource. I now have to make some kind of a table (like a saw table) for cutting depron plates. I will need a large bow for wingcutting (polystyrene, XPS etc.) and a long wire set-up with one end fixed to an underplate for making the upperhalf of a round fuselage such as one of the FW190. That way i can make the fuselage of two peaces of foam where one piece is box shaped (build of depron plates) and the other piece is curved. Should be easy to glue them together making one fuselage all together.

grtzzzz.
Martijn Kaandorp is offline Find More Posts by Martijn Kaandorp
Reply With Quote
Old Jan 17, 2005, 05:30 PM
Registered User
ricky's Avatar
Calgary, Alberta Canada
Joined Oct 2003
130 Posts
Hi Guys foam cutting!
If you having problems getting nichrome, in my hand I hold Cablea's single strand
none corrosive stainless steel fishing line 192 ft. dia .022 in. test 105. When I had
problems getting any length of nichrome, someone on this group suggested steel
fishing line and I really like it. Reasonable in price and for the fellows in Ca. should not
be hard to find there and if it breaks which does not happen very often., I have 192 ft.
of it. I do a lot of foam cutting, blue, EPP and Depron, also so built my own foam
cutter from a 25v center tap transformer, RS# 273-1512 if you do a search on this
site you can come up with a schematic for it. Good Luck!
ricky
ricky is offline Find More Posts by ricky
Reply With Quote
Old Feb 24, 2005, 06:11 PM
Registered User
Joined Feb 2005
5 Posts
Easy source for nichrome wire is Manhattan Supply Co. On the net as mscdirect.com.
Their paper catalog is on very thin tough paper, imagine three phone books in a stack,
over 3000 pages. Anything you need for tools, supplies and so forth. Materials section
has a fair selection of metals and plastics but not much foam. Did find some EPP in 2.2 lb. density. Check it out, the website is kinda awkward but it will get the job done.
Hope this helps ....Kohned
kohned1 is offline Find More Posts by kohned1
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
foam cutting tapered tips GaryO Composites Fabrication 5 Aug 11, 2005 12:24 AM
Pink Foam cutting tips microflyer77 Foamies (Kits) 1 Mar 05, 2002 12:42 PM
Foam cutting CNC software foam_man Foamies (Kits) 10 Sep 08, 2001 09:50 AM
Computer Power supply for Foam Cutting? dwood99 Foamies (Kits) 5 Jul 18, 2001 02:22 PM
Foam cutting - electronics question AC to DC ChrisD Power Systems 5 May 02, 2001 06:11 AM