HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jan 25, 2009, 04:35 PM
Starting to Rebuild
Wingnut31's Avatar
Fayetteville NC
Joined Jun 2006
1,028 Posts
Discussion
Hot Wire Frustrations

I'm getting pretty frustrated with finding a power supply for a hot wire cutter. I have blown out transformer after transformer. I have scavenged some from appliances and had no luck, not enough amps there. The ones at Lowe's lasted about 30 sec and didn't get hot enough. I bought a car battery charger but it's short circuit detection trips.

Is there a battery charger out there that doesn't have the circuit protection on it, or is there a way to disable the protection?

Does anyone have a specific transformer I can get and where to get it that will work? I even tried to power it with a car battery. It worked but was too hot. Could I use a rheostat to regulate the voltage or pile on some 1 ohm resisters till I get the right temp? I'm trying to use some thin music wire to heat a 48" bow.
Wingnut31 is offline Find More Posts by Wingnut31
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 25, 2009, 07:24 PM
Registered User
Joined Nov 2007
893 Posts
Generators can operate at near short circuit with no problems. You could try using a permanent magnet motor as a generator. Or I would use an automotive alternator driven at about 6,000 RPM.
mjsas is offline Find More Posts by mjsas
Reply With Quote
Old Jan 25, 2009, 08:09 PM
Registered User
Ron W3FJW's Avatar
Tacoma WA
Joined Feb 2008
561 Posts
A forum search would bring this link up. All you need to know is discussed in this thread.
http://www.rcgroups.com/forums/showthread.php?t=948665
Ron W3FJW is offline Find More Posts by Ron W3FJW
Reply With Quote
Old Jan 25, 2009, 08:09 PM
Starting to Rebuild
Wingnut31's Avatar
Fayetteville NC
Joined Jun 2006
1,028 Posts
I was looking at my wife's sewing machine and thought about her pedle speed control...I better no, she would kill me.
Wingnut31 is offline Find More Posts by Wingnut31
Reply With Quote
Old Jan 25, 2009, 10:26 PM
Registered User
dusty IV's Avatar
Joined May 2004
1,590 Posts
Quote:
Originally Posted by Wingnut31
I'm getting pretty frustrated with finding a power supply for a hot wire cutter. I have blown out transformer after transformer. I have scavenged some from appliances and had no luck, not enough amps there. The ones at Lowe's lasted about 30 sec and didn't get hot enough. I bought a car battery charger but it's short circuit detection trips.

Is there a battery charger out there that doesn't have the circuit protection on it, or is there a way to disable the protection?

Does anyone have a specific transformer I can get and where to get it that will work? I even tried to power it with a car battery. It worked but was too hot. Could I use a rheostat to regulate the voltage or pile on some 1 ohm resisters till I get the right temp? I'm trying to use some thin music wire to heat a 48" bow.
================================================== ===============

There are more ideas on PS for foam cutters then I can comprehend. Most of them are bogus imho. I tried various ideas that didn't work at all. Biggest problem I had was burnt out wires half through cutting. Grrr.

People claimed they worked but sure didn't for me so I designed my own.

I made mine a very long time ago when huge transformers were available cheap. That's the first hurdle but I have no idea where to find one now. If you are into electronics I can give some details on what I did. It's to confusing for most folk however.

To keep the wire from burning out I used a constant amp regulator circuit and still have the original wire in use. It was just a common length of piano wire from the hobby store.

Picture of my swing arm with a watts link cutter. If you look close you can see a gray box at the bottom with the PS. I sure feel your pain on trying to get a supply to work.
dusty IV is offline Find More Posts by dusty IV
Reply With Quote
Old Jan 26, 2009, 03:51 AM
Registered User
Australia
Joined Sep 2001
1,509 Posts
I've been using a 12V 8A car charger for many years with no problems.

Dave
david_dewit is offline Find More Posts by david_dewit
Reply With Quote
Old Jan 26, 2009, 10:30 AM
Registered User
Dan Baldwin's Avatar
United States, CA, Norwalk
Joined Apr 2004
2,715 Posts
Quote:
Originally Posted by Wingnut31
I'm getting pretty frustrated with finding a power supply for a hot wire cutter. I have blown out transformer after transformer. I have scavenged some from appliances and had no luck, not enough amps there. The ones at Lowe's lasted about 30 sec and didn't get hot enough. I bought a car battery charger but it's short circuit detection trips.

Is there a battery charger out there that doesn't have the circuit protection on it, or is there a way to disable the protection?

Does anyone have a specific transformer I can get and where to get it that will work? I even tried to power it with a car battery. It worked but was too hot. Could I use a rheostat to regulate the voltage or pile on some 1 ohm resisters till I get the right temp? I'm trying to use some thin music wire to heat a 48" bow.
What size music wire are you using?

Dan
Dan Baldwin is offline Find More Posts by Dan Baldwin
Reply With Quote
Old Jan 26, 2009, 10:58 AM
Registered User
earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
12,943 Posts
Do you have any surplus electronics stores in your area?
I had bought a huge monster transformer there from them a while back.
http://www.tannerelectronics.com/
I think what was doing you in was the high duty cycle used to heat up the wire. The smaller transformers can't handle the current needed for too long like that. So you have to up the power levels a lot to keep the transformer from overheating.
So probably something around a 200w transformer is needed.

The old time big transformers are sort of prehistoric nowadays. Everyone changed over to switching power supplies.
If you know what the current levels are, a big heavy duty switcher may be the way to go. But you have to get a heavy duty one as it might shut off the output if it thinks it is a short circuit.

Anyone still have a big 12v battery charger that one could get? They usually have or had big transformers in them.
Maybe something like this would do the trick:
http://cgi.ebay.com/PYRAMID-PS36KX-3...12129005r31532
earlwb is online now Find More Posts by earlwb
RCG Plus Member
Latest blog entry: My new Gaui X5 Rc Helicopter
Reply With Quote
Old Jan 26, 2009, 11:05 AM
Registered User
Joined Oct 2004
2,779 Posts
You can also just use a 12 volt battery as a buffer, just keep it charged with the charger when not in use, or top up the charge when you expect to use the foam cutter the next day.
Brandano is online now Find More Posts by Brandano
Reply With Quote
Old Jan 26, 2009, 11:22 AM
Say when.....
quigley257's Avatar
United States, MO, Hillsboro
Joined Sep 2005
1,389 Posts
I built mine using the instructions I found on-line. It uses a transformer and a rotary light dimmer switch. It works great!!

Here is the article I followed to make mine...http://www.instructables.com/id/Hot-wire-foam-cutter/

--quigley
quigley257 is offline Find More Posts by quigley257
Reply With Quote
Old Jan 26, 2009, 01:57 PM
Registered User
earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
12,943 Posts
Hummm, I wonder if the guitar string wire was a little too thick for your purposes. The heavier the wire the more current or power is needed to power it up so it gets nice and hot.
earlwb is online now Find More Posts by earlwb
RCG Plus Member
Latest blog entry: My new Gaui X5 Rc Helicopter
Reply With Quote
Old Jan 26, 2009, 02:47 PM
Say when.....
quigley257's Avatar
United States, MO, Hillsboro
Joined Sep 2005
1,389 Posts
I have been using Sig braided stainless control line flying wire for cutting. It works quite well.

--quigley
quigley257 is offline Find More Posts by quigley257
Reply With Quote
Old Jan 26, 2009, 03:00 PM
Registered User
vintage1's Avatar
East Anglia, UK
Joined Sep 2002
29,703 Posts
stainless fishing trace is also a good way to go.

Good source of transformers for 12v use is low voltage halogen lights. SOME electronic ones will work with a dimmer on the mains side.

However a dimmer on the LV side is a bit nicer.
vintage1 is offline Find More Posts by vintage1
Reply With Quote
Old Jan 26, 2009, 03:58 PM
Starting to Rebuild
Wingnut31's Avatar
Fayetteville NC
Joined Jun 2006
1,028 Posts
I was using some thin music wire I can't remember the thickness but you wouldn't want to use it as a control rod. I also used guitar string the thinnest from the pack of replacments.
Wingnut31 is offline Find More Posts by Wingnut31
Reply With Quote
Old Jan 26, 2009, 04:51 PM
Starting to Rebuild
Wingnut31's Avatar
Fayetteville NC
Joined Jun 2006
1,028 Posts
Ok, I have been looking around, no electrical suppy shops have or will look for one here, so now I'm on Ebay. Here is what I have found.

Option 1

Portable Option 2

Rope Cutter Opt 3

Opt 4

Option 5 I will have to toss or modify the jig

Progressiavly they get more costly. Do these look like good options?

Thanks for all the help guys.
Brian

I wanna cut 48" panel of Dow and Owens Sheathing into 3/8' to 1/4" sheets
Wingnut31 is offline Find More Posts by Wingnut31
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Batt charger as power/thermal source for hot wire foam wing cutting bow? - UK Steve Wrona Foamies (Kits) 3 Feb 29, 2004 03:07 PM
alternatives to hot wire foam cutting? breadboy Foamies (Kits) 7 Oct 04, 2001 07:18 PM
epp foam glue to cut with hot wire? inedesca Scale Kit/Scratch Built 4 Jun 08, 2001 08:08 AM
hot wire technique (HELP!) DeaninMilwaukee Foamies (Kits) 13 Apr 25, 2001 04:41 PM
How do i make my own hot wire rig? PunkerTFC Electric Plane Talk 21 Apr 22, 2001 09:50 PM