Foam cutter power supply

[Thedroid]

I'm building a hot wire foam cutter to build archery targets with. I need to be able to cut through multiple layers of expanded styrene, and a hot wire cutter is just the ticket. I'm using a 48" wide piece of nichrome wire, and I need an adjustable power supply capable of putting out 48 volts with a 10 amp rating. I hooked up the wire cutter to a 0-120 10A variac as a test today in order to see what I needed, and I wouldn't hesitate to use it, but its not for me, and the variac can put out a full 120.

Any ideas that won't break the bank?

 

[niget2002]

I just always used a car battery charger. The type with 6v and 12v and low/high amps on the 12v. High amps at 12v should cut, maybe just a bit slower than the 10 amps you used did.

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[Thedroid]

I don't think that the battery chargers voltage is high enough to drive more than maybe an amp or so through this length of wire. Unless I go with a thicker wire, I need around 48 volts which gives me around 4.5 amps through the wire. This makes the wire glow orange and cut real well. I'd like to hook up the variac to a transformer to keep things safe, but I can't find a transformer thats rated at what I want.

 

[Mattlt]

Find a cheap welder.

 

[Lightning rod]

Your proposed power supply is about 250w

That's going to cost you about $300 new.

Is this out of your price range?

Maybe you can search some of the electrical surplus supply houses

For a step down transformer. 120/48 v 250 va . That should work for you

Like this
http://ca.mouser.com/ProductDetail/Hammond-Manufacturing/167P50/?qs=sGAEpiMZZMumryolnogYRrHNjb2261AV

Build your own

 

[nehog]

Again, consider used computer power supplies! Lot's of amps, and with multiple supplies having outputs connected in series you can get voltage and current. (you cannot series one power supply's outputs normally, which is why you need multiple supplies...)

 

[Kevin C]

One issue is that you want an adjustable 48 V supply. There are 48 V switchers, but they typicly have a limited ( if any) adjustment range.

Adjustable lab power supplies are hard to find at 10 A / 48 v.

You could roll your own using a fixed 48 V supply and PWM driving a mosfet to drive the heater and control the output. There are a number of forums that address doing this.

MeanWell has several 48 V supplies are carried by Jameco. I just bought an 800 W for around $200.

http://www.meanwell.com/search/SE-600/default.htm

Data sheet for a 600W

You could also use your Variac to drive a 120 to 48V stepdown transformer. That would limit the max voltage.

You can find PWM controls on E Bay most seem to have a max of 40 V

http://www.ebay.com/itm/DC-Motor-Speed-Controller-Pulse-Width-Modulation-PWM-Adjustable-Controller-/370763041168?pt=LH_DefaultDomain_0&hash=item5653330990

 

[Kevin C]

http://www.ebay.com/itm/9V-60V-20A-DC-MOTOR-SPEED-CONTROL-PWM-HHO-RC-CONTROLLER-24V-12V-36v-48v-MAX-600W-/170974195361?pt=LH_DefaultDomain_0&hash=item27cedb2ea1

Possible controller for a 48V supply.

 

[justsam]

Check for old telephone company surplus. Most central office equipment is 48vdc, and station equipment is 24vdc.

 

[niget2002]

We used metal fishing line on a 36" bow for cutting rc airplane foam cores.

I still say start with the power supply, then find the size wire that works with it. It will be cheaper in the long run.

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