Teardrops n Tiny Travel Trailers

Looking for an alternative power source for a hot wire cutter and trying to avoid expensive electronic devices (as GPW would say,"Thrifty"). How about a 12v battery? Or one of those big 6v flashlight batteries?

It has been many years since physics in college, which has been my only exposure to electronics, and to much other stuff piled on top of it. Volts, amps, watts, resistors, potentiometers, lions and tigers and bears.

Help!


Jim

Here's a site that helps you calculate how many volts and amps you need for what temperature on what kind of wire.
http://hotwirefoamcutterinfo.com/Hot_Wi ... ction.html

I bought 20ga nichrome for my straight cutter and powered it off a "wall wart" 12 VDC power supply on a lamp dimmer. It worked fine.

But for my 16 ga "dado cutter" where I shaped the wire to cut a specific profile, I needed 5 or 6 Amps at 3 VDC, so I got some NiMH D cells and used those. They were a pain to recharge because I didn't buy a matching charger, but they got the job done.

Different applications want different temperatures and wire lengths and diameters, all of which affect the volts and amps required.

<Chas>

Ok, so what temp do I need? Isn't there a simple way to do this without resorting to expensive and confusing electronics? I just want to cut, Kerf and shape some pink foam, not become an electrical engineer, nor do I care to break the bank.

My mother threw away my trains 25 years ago , so no transformer. You mentioned a lamp dimmer, but those don't work with DC as I understand. I do have a "trickle charger" that I use to recharge a 12 v deep cycle battery. Would that work?

If you are just going to cut straight lines in rigid insulation sheets, I suggest you use a thin blade kitchen knife, such as a boning or fileting knife. Faster, easier, no fumes and you don't have to build a table and an arm like a jig saw.

All my straight square edge cuts were made with a knife, I used hot wire only for taper cuts or when cutting groves or router-like edge shapes.

You need a DC power supply to plug into the lamp dimmer, a wall-wart power supply from an old laptop or printer or... might be hanging around? Don't connect nichrome wire directly across a lamp dimmer output!

<Chas>

Ah! So the dimmer goes between the power supply and the wall! That makes much more sense! Wall warts? Got plenty of them! Then I guess I just experiment with the settings?

Thanks for all your help!

How about a 12v battery?

FWIW, I made up a bow using Ernie Ball guitar strings #8-11 and powered them off a 12V deep cycle. I was cutting through big 24" foam blocks so it didn't have enough power for the job...but it worked great on 1" pink foam. I wired it with 12ga speaker wire through a momentary push button that I held in my hand. It was all stuff I had laying around.

Thanks, Wobbly. That sounds about like what I had in mind. Never thought about the momentary switch though. Hmmmm.

I am using a manual 2/10/50 amp Schumacher battery charger. The new electronic chargers will not work because they are wanting a voltage signal from the battery. If you can find one of these older chargers they work great. I use different wire lengths to change the wire temp. I have read that others have put a dimmer switch in line to control the temp as well.

I used a halogen lamp power supply that outputs 5 amps at 240V, I wired in a dimmer switch to the live cable going to the transformer and added crocodile clips to the wires coming out of the transformer.

I can then attach the clips to the wire I am using, which is 1.2mm stainless steel. I can cut foam really easily and with the dimmer switch (it also allows me to turn it off and on) set the temperature of the wire so it goes through the foam nicely. The wire loops through a piece of wood where I have screws holding it in place, the clips attach to these screws.

I don't have any pictures but ghcoe's build thread is where I got my inspiration/plagiarism!

Cool about the dimmer switch.

Just a consideration ... when using a dimmer switch or lamp power supply , you'll have AC voltage on the wire ...You could get a tingle ... Using my 5A Variac , has AC on the wire , which we’re careful Not to touch ... besides being HOT ... USE CAREFULLY !!!

Just to add, my transformer didn't like being run off a dimmer switch, and has burnt out. will need to find something a bit more resilient.

That said it was working well up until it failed, a crocodile clip fell off a terminal and then it didn't work so I don't know if that was the cause instead of the dimmer switch.