HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jun 15, 2004, 02:52 PM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
1,137 Posts
Best Voltage / Amperage /AC/DC for Foam Cutting

Is there a table or rule of thumb for the optimum foam cutting setup?

Is AC or DC better or more controllable?

Is it better to control heat with constant voltage and vary the amperage or constant amperage and varying voltage?

Is there a best voltage or amperage for foam cutting?

Is it better to scrap the first three questions and just go for a temperature? Which leads to what are the melting or optimum temperatures for cutting the different materials such as blue foam, pink foam and EPP?

Lastly - I am assuming that any answer to any of the above questions is just a starting point because the each piece of foam will probably have a different density or moisture content even within a given type of foam.
mdennis is offline Find More Posts by mdennis
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 17, 2004, 01:33 AM
Registered User
Australia, NSW, Sydney
Joined Feb 2003
1,114 Posts
mdennis,

My hot wire set-up, which I use primarily for slicing blue Styrofoam and EPP into thin sheets, uses a 0.5mm (.020 inch) nichrome wire, and runs off my lab power supply which produces 3A max. This is more than enough current to cut these foams in straight lines but if I cut wing cores (with curved wire paths) I need more current to keep the wire sag under control. The relativey low current also seems to give a better surface finish and better thickness tolerance which is important for the thin sheets I cut.

I use DC, but I don't see any reason that AC can't be used instead. I set the supply up in constant current mode, but this may not be the optimum. If you could measure the wire temperature and control to that, I think this would be the optimum set-up.

Graham.
Salto is offline Find More Posts by Salto
Reply With Quote
Old Jun 17, 2004, 01:46 AM
Dismembered Member...
arx_n_sparx's Avatar
Niagara Falls/Toronto area
Joined Dec 2003
4,536 Posts
Well, I'm using this power supply: http://www.nsrca.org/technical/tip_t...wer_supply.htm
I honestly don't know the voltage or current thru the wire, as I haven't bothered measuring it. I just put a nice big knob on the potentiometer, and have made notes as to where the "dial" is set for the various foams. The power supply has enough "smash" for what I'm doing - my bow is almost 5 ft/1.5 m long. I'm using SIG control line wire (.018") for the cutting wire.

I tried asking questions similar to what you are, mdennis, and the answers I got back were basically "try it on scrap until you get it right". I don't think the guys were being flip, either. I DO know that if you get wavies (like a ruffled potato chip) in the cut, your heat is too low (ask me how I know *wink*). Like Salto/Graham, I'm using mine to slice foam sheets, and I also have a vertical "scroll saw" set up for cutting out parts.

Brad

ps - try searching "KreAture" - he did a thread on this. Found it: http://www.rcgroups.com/forums/showthread.php?t=197494
arx_n_sparx is offline Find More Posts by arx_n_sparx
Last edited by arx_n_sparx; Jun 17, 2004 at 01:49 AM.
Reply With Quote
Old Jun 17, 2004, 09:00 AM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
1,137 Posts
Great info - Time to make a pile of foam scraps. Thanks

Next is vacuum bagging class with short courses in fiberglass, kevlar, carbon fiber, mylar and making bigger stickier messes.

Mark
mdennis is offline Find More Posts by mdennis
Reply With Quote
Old Jun 17, 2004, 04:51 PM
Dismembered Member...
arx_n_sparx's Avatar
Niagara Falls/Toronto area
Joined Dec 2003
4,536 Posts
Quote:
Originally Posted by Salto
mdennis,

My hot wire set-up, which I use primarily for slicing blue Styrofoam and EPP into thin sheets, uses a 0.5mm (.020 inch) nichrome wire,
Graham.
Didn't notice this at first. I'm not using Nichrome wire, and I know that a LOT of guys swear AT it instead of by it. Most use stainless steel - either braided (like moi/many use fishing leader) or solid (real aircraft safety wire - .020"). NiCr sags and is weak. I have a LOT of tension on my wire - if you are musically inclined, I'm between the 2 middle strings (D & G) on a guitar over that 5' length! I don't have to worry about the wire sagging during cuts.

Brad
arx_n_sparx is offline Find More Posts by arx_n_sparx
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
whats' the best wire for foam cutting ? Raglan Scale Sailplanes 16 Mar 23, 2008 07:20 PM
CNC software for foam cutting KAMarks The Builders Workshop 0 Sep 15, 2002 09:20 PM
Using Orbit charger for foam cutting tom_yellowblue Power Systems 6 May 02, 2002 03:49 PM
Templets for foam cutting J Morgan Power Systems 29 Feb 18, 2002 06:38 AM
Computer Power supply for Foam Cutting? dwood99 Foamies (Kits) 5 Jul 18, 2001 02:22 PM