[toneV8]

I have wire for foam cutting:

Nickel-Chrom 0,2mm/0,008inch resistance on one meter is 16,8 ohm

Nickel-Chrom-Titan 0,4mm/0,016inch resistance on one meter is 8 ohm

How to calculate what kaind voltage and ampere I need if I use 1 meter of wire.

Does anybody have schematic for foam cutting.

[blackbeard52]

Try this....

http://nsrca.org/technical/tip_trick...wer_supply.htm

Hope it helps
Bob

[SteveC68]

I built that power supply about 2 months ago and it cannot be done for the $30 that the author claims. A few of the parts are no longer available at Radio Shack. Also the transformer listed is only good for 2 amps. I have this supply connected to a 24" bow with .018" stainless nichrome wire. With the supply set to the hottest setting it still has a lot of drag through the foam. It would work for extremely slow cutting speeds at best. How much money are you willing to spend on a power supply?

Also are you going to be using this with a CNC machine? If so are you planning on using GMFC or Jedicut (both of which have heat control from a DC power supply)?

Steve

[toneV8]

For now without cnc only testing wire and building proper power supply. So do you plane to build some other power supply.

[SteveC68]

I plan on buying a power supply already built. You can get an excellent power supply on ebay. Just search for Mastech power supply. You need at least 5 amps. If you want to build a good power supply then you will end up spending close to 3/4 of the cost of the one you can buy on ebay with almost none of the features. When I built my supply I bought most everything from mouser, and a local store. I ended up with over $50 in receipts, and a power supply that isn't that great.

[miljnor]

The trick with building your own power supply is scavenging used sources!

Otherwise your ARE better buy a pre-made because Steve is right the parts cost is close to a pre-made with a lot less features and not pretty besides.

[toneV8]

I am researching on web power supply for foam cutting. Problem is electronics - potentiometer, transformer is not a problem I have couple of them witt different voltage and ampere.

[SteveC68]

Try the power supplies on this page.

http://users.belgacom.net/hamradio/homebrew.htm

There is an 18V 4 amp DC supply that looks pretty easy to build. You have to scroll down on the left side of the page to get to the Power supply schematics.

[miljnor]

Did the sight get hacked?

this is the only forum i could post in?????

[blackbeard52]

Havent ordered from here yet but prices are unbelivable even if they are kits


http://www.anykits.com/catalog/

Bob

[blackbeard52]

A very good conversion of PC PSU..... http://www.antennex.com/preview/archive3/powers.htm

bob

[SteveC68]

How about these Power Supplies? Only problem is they are non adjustable output. However if you run a board with heat control like the HobbyCNC Foam Pro or the MM2001 and use either GMFC or Jedicut then these power supplies would work as the board and software control the wire heat using pulse width modulation I believe.

http://www.mpja.com/prodinfo.asp?number=16013+PS

Steve

[Ornery]

Hey,

I use a automotive 12v/15 amp battery charger with a 10amp Variac.
The Variac is between the charger and the wire.
It works great to about 48" of 18ga. NiChrome. The charger must have a MANUAL setting on it.
I use one with a setting of 12vdc/10amps pretty much full blast most of the time. I if I need more heat, I just move the alligator clips closer together.
Or better still, cut dead slow...

The only problem is at the low end the Variac doesn't like voltages between
1v-3v, no fine tuning, which sucks for tiny detailed cuts with short wire. Maybe I'll stick another dimmer in the circuit somewhere...I've blown up a few wires using 120VAC being impatient, and wanting to blast through a job with hight heat. Spectacular white hot wire flying around on the end of a spring!! Wear your eye protection!!.

I've also jammed a digital multitester into the powerstrip, which is nice
to keep track of what voltage works with what length of wire, and a nice little
12 v indicator light, taped on the side. Funky as hell, works fine.

I'm trying to figure out how to get some kind of monster power supply going,
like 100v so I can gang cut 6 or 8 wires at a time. Some kind of parallel circuit I would imagine, calculated for the resistance of each length of wire.
Sounds like a total pain.

Mmmm! I smell burning plastic!!....oh wait....it's my frozen pizza!

Ornery

[radcliffe]

Link to a schematic by Don Bladier for applying a pulse width modulated 24 bolt supply to cutting wire. http://members.fortunecity.co.uk/slm...interest2A.htm

link to 24v 10amp transformer, $18.95 that can be used.
http://www.mpja.com/prodinfo.asp?number=7846+TR

Harold

[High Seas]

My quick 2 cents -- the automotive battery charger I use is a 6/12 volt charger - that you can set to 6 or 2 amps.
Works fine with a 30 inch bow - and if it seems like it'll get too hot - I cycle it on and off with a foot switch. Got it (the charger) Wally World as I recall - cheap as chips. The foot switch at Harbor Fright! - Happy Halloween =:0>

:cheers: Jim