Hot Wire Foam Cutter

[Stephen]

Several years ago I made a foam cutter power supply. i used plans found on the internet and power transformer from Radio Shack. I would like to make this agian however since Radio Shack is closed the trasfomer is no longer avaiable. The part number as I remeber was 273-1512B 25.2 V AC 2 amp. Has anyone built there own and what are you using for a power supply?

[William DeMauro]

Just use 2 server power supplies in series We use them to power our chargers but 12V should be more than enough. Plans are all over the internet and on RCGroups. just google it. Power supplies are cheep and easy to convert. These are cheap

[Brent Williams]

25.2v 2a transformers are available online for around $20.  Amazon, eBay, ect.

[Tim Wescott]

25.2v 2a transformers are available online for around $20.  Amazon, eBay, ect.

Or if you want a better chance of getting something that's intended for a professional audience, DigiKey, Mouser, Newark or (in the UK) Farnell.

[Howard Rush]

You don't want voltage to vary under load.  Don't use a dropping resistor.  A variable, regulated power supply would be the bee's knees.   

[Mike Alimov]

My battery charger has a hot wire mode, and the current is adjustable down to 100 mA resolution. Junsi iCharger 306B, a great piece of hardware. It does however need an external 12V power supply.

[Jim Hoffman]

I also use my battery charger for foam cutting. Progressive RC icharger 306B .   It needs a 12volt power supply.  Works great 

[George Truett]

I have been using a variable AC power supply from Circuit Specialists for 3 or 4 years now on one of my foam cutters.  I use the 5 amp digital version, very easy to set for repeatable results.
https://www.circuitspecialists.com/variac-variable-ac-ps05kva_with_digital_display.html

[John Rist]

https://www.mpja.com/

MPJA has a verity of power supplies as well as good supply of soldering irons.  I have there Solder Station with LED Display, ZD-929C,  https://www.mpja.com/Solder-Station-with-LED-Display-ZD-929C/productinfo/15845+TL/.  It heats fast and is temperature controlled.

[Tim Wescott]

MPJA is a very nice surplus house.

They even have cheap variable bench supplies, of the sort that Howard mentioned.  They're MPJA branded, which probably means cheap Chinese, but mine hasn't burned down my shop.  Yet.

[Stephen]

Thank you all very much for the help. Supper helpful !!!!

[Jim Carter]

Hi!  What the heck!!  Let me throw in an idea of what I have and still use ... an old ho model railroad transformer!  Fully variable dc voltage with a built-in circuit breaker, if it was ever necessary (never had it pop, that I remember).

Jim Carter

[Steve Helmick]

I used a 120v. Dremel remote variable speed control. Other than the potential for electrocution, it worked fine. Think of it as a mild Tazing....  Steve

[Dennis Toth]

Question - do you want a DC power supply that is variable voltage (i.e. HO transformer) or something that is a variable current (don't know what that is but someone out there knows)?

Bests,    DennisT

[phil c]

Question - do you want a DC power supply that is variable voltage (i.e. HO transformer) or something that is a variable current (don't know what that is but someone out there knows)?

Bests,    DennisT

Kind of an electrical summary-  V=IR  Voltage across the wire  equals the amperes X resistance.  I got some thin, modified ni-chrome wire about 0.01ohms per meter.  It's very thin, plenty strong, and very corrosion resistant.  The latest driver for the wire is made from a light dimmer switch,  an electrical box, and a face plate.  The box is wired so a 100watt bulb is in series with the cutting wire and a slider switch turns the wire on and adust the power to control the heat.  You can buy all the safety certifed parts at places like Home Depot.

The other big problem is getting the right balance between cutting speed and power.  Once you've found found the right temperature and the right cutting speed 1/8 hard plywood or micarta and a method to to make the end airfoil templates it's quite possible to cut wing panels on a table. I had to hookup a CNC version to let me do two or three things at once.  A cheap power supply(above), a stiff platform, and some cheap ball-slides and one person can cut wing blanks and it's possible to cut nearly perfect wing panels everytime.  Look at some of the sites for the plastic extrision molding.

Anyway, that will give you a start, or give me a call.  I've got about a mile from a leftover partial spool from one of the wire manufacturers, about 5 miles of 0.009 wire.  Inconel  is considerably strong when hot, but it still is amazingly strong.
Send me a envelope and a stamp I'll cut 6-10 ft.+

Phil Cartier

[Istvan Travnik]

Mine is:
https://www.banggood.com/search/nice-power-r-sps3010.html?from=nav

It is better to use switching system precision laboratory supply unit, since does not heating the room/environment, like others.
For precise works (blue / pink foam cutting) it is strongly advised to use digital, with adjustable both voltage and current control.
Istvan

[AMV]

The simplest and most cost-effective system is one with a stepdown transformer, a stock dimmer, and a fuse.
This site (especially this page) has all the details and supplies you need to build your own.

Cheers
-Andrey

[Gerald Arana]

I used a 120v. Dremel remote variable speed control.  Steve

Me too! Works beautifully.

Cheers, Jerry

[Brent Williams]

I have used a simple Sears (Schumacher) 12v car battery charger plugged into a router variable speed control from harbor freight which plugs into the 120v wall.  I've massacred a lot of foam with this rig.  I mostly use it to cut foam sheets into custom packing material for boxes.

[Istvan Travnik]

Why I seem to "advertise" precision, digital laboratory supply unit, with adjustable voltage & current regulation?
I use it not soleily for truncate foam blocks, but for several other, very fine purposes:
- making hinge slots in bluefoam wings with miniature soldering iron
- I made small, precise "heat lancets" to make small (1x2 mm) grooves into bluefoam pieces, for carbon filament reinforcements,
- the carbon filament can be used as resistor-selfheating by electric current, to better suck up the resin, after inserted into its groove...
...and so many other purposes.
Istvan