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Cheap ($30+-) and easy to build hot wire foam cutter made from commonly available parts. Cuts styrofoam for surfboards, model plane wings, sculpture, model train or tabletop wargame terrain, 3D sign letters, mold models for lost foam casting, etc.
5/17/2007, Important note! Please be sure to read the comments that other users have left below. There's a LOT of good info there. Check out the links that folks have posted and study what they've said here and you will be able to build a cutter thats suited to your budget and the materials you have access to. There are a lot of alternatives listed or linked below for the frame, the transformer, the wire, the enclosure, and the heat control. Don't underestimate the power of comments! :)
5/17/2007, Important note! Please be sure to read the comments that other users have left below. There's a LOT of good info there. Check out the links that folks have posted and study what they've said here and you will be able to build a cutter thats suited to your budget and the materials you have access to. There are a lot of alternatives listed or linked below for the frame, the transformer, the wire, the enclosure, and the heat control. Don't underestimate the power of comments! :)
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The parts should be pretty easy to find.
1. 12 foot, 16 guage extension cord, about $2 at Home Depot
2. 2 wooden yard sticks from the Home Depot paint department, $.97 each
3. 4 #10-24 x 1.25" machine screws with nuts, $1 at Home Depot
4. 10 #10 washers, $1 at Home Depot
5. About 12 feet of strong, low-stretch string. I used 200 lb dacron kite line.
6. A single-pole dimmer switch. About $10 at Home Depot.
7. A 25 volt, 2 amp transformer, $10.49 from Radio Shack.
8. An electric guitar string, about .10 - .16 size. I think around $1? You can get these individually at a music store or you can use either of the 2 smallest strings from a packaged set. You should keep a spare handy because they can burn out or break from too much tension.
9. A length of two conductor electrical wire with a regular plug on the end. I salvaged mine, but you could use another extention cord if you like.
10. A piece of wooden dowel or stiff plastic rod about one foot long (not shown). I used a bamboo skewer.
11. Optional: 4 regular-thickness CD cases. These are for the box that holds the transformer and dimmer switch, but you would be much better off with something like a "project box" from Radio Shack.
1. 12 foot, 16 guage extension cord, about $2 at Home Depot
2. 2 wooden yard sticks from the Home Depot paint department, $.97 each
3. 4 #10-24 x 1.25" machine screws with nuts, $1 at Home Depot
4. 10 #10 washers, $1 at Home Depot
5. About 12 feet of strong, low-stretch string. I used 200 lb dacron kite line.
6. A single-pole dimmer switch. About $10 at Home Depot.
7. A 25 volt, 2 amp transformer, $10.49 from Radio Shack.
8. An electric guitar string, about .10 - .16 size. I think around $1? You can get these individually at a music store or you can use either of the 2 smallest strings from a packaged set. You should keep a spare handy because they can burn out or break from too much tension.
9. A length of two conductor electrical wire with a regular plug on the end. I salvaged mine, but you could use another extention cord if you like.
10. A piece of wooden dowel or stiff plastic rod about one foot long (not shown). I used a bamboo skewer.
11. Optional: 4 regular-thickness CD cases. These are for the box that holds the transformer and dimmer switch, but you would be much better off with something like a "project box" from Radio Shack.
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Since there are 3 output wires. It's will be something like 12-0-12. Meaning that if you use any of the left or right wire with the middle wire, you'll get 12V output, but if you use the two outermost wire only(without the middle wire), you'll get 24V.
A bit confusing, but i hope it helped :)
Any idea what I might be doing wrong?
Thanks in advance.
My problem is that when I cut I have strands of plastic trailing off of the cut edge. Why do I get those?
Forgot to post my email address.
rmndela@yahoo.com.
I have just finished assembling and testing a Hot wire foam cutter.
Works perfectly in cutting large junk styro foam materials into thick slabs or thin slices or into any form.
The power supply is quite sturdy at 6 amperes and has fully-controllable current output to vary the heat of the nichrome wire.
Most of the parts were just salvaged from junk electronics products and few parts were bought from an electronics store. The circuit is easy to assemble for those who could follow instructions.
Please email me if you need further clarifications.
Rod
A Center Tap is a wire that is connected to the transformer winding RIGHT AT the middle. As other commenters have mentioned, when that wire is used in conjunction with one of the other [end of the winding] wires you get PRECISELY ONE HALF [1/2] the voltage, AND if it is wire "like a ground" on two seperate circuits each connected to ONE of the winding "end" wires you get TWO seperate circuits of one half the specficied voltage each.
If you just use the two end wires then you get the full rated voltage.
Again, I'm an electrical/electronics novice, but this is the way it was explained to me. Hope this helps for novices to understand "Center Tapped" transformers.
By the way, transformers can be ordered with several taps [on both the secondary (output) and primary (input) windings to obtain many combinations of voltages and current outputs].
They also have thermal protection .
.The only problem I've had is figuring out just the right wire. I used an old #1 e guitar string. But if anyone has any suggestions let me know. I would love to turn this into an automated CNC type system but it's in the drawing phase, and any input will be greatly appreciated. All I have is a regular PC an a free CAD software. Well thank you all and I hope these help(This is not design and I take no credit for it.)
great place to get wire is the local welding supply house. .025 or .030 high
grade stainless steel (316 or 316L) (L is for low carbon) or Inconnel wire
works great. Plus, a good power supply is a small 2 (two) amp battery charger,
or for longer wire operations a 40-200 amp will work.
*A Transformer doesn't require a ground - your work should still be grounded, but not the transformer.
There are three wires used in AC, Hot, Neutral and Earth Ground. It sounds like you are using this green wire as if its the AC neutral wire when in fact it is Earth Ground. In DC, we talk about ground being the return path to our electrical circuit, but this ground is not the same as Earth Ground. In the U.S./Canada, AC neutral wire is usually white and black is hot. See the following link for AC color codes:
http://www.allaboutcircuits.com/vol_5/chpt_2/2.html
If the device also converts AC to DC, then it includes a rectifier and can also include a transformer before rectification. It is also called a DC power supply. If the DC power is clean and maintains voltage or current, then it is a regulated power supply or linear regulator.
You can use either AC or DC to heat a wire. The wire acts as a resistor.
If you use a light dimmer with a transformer, you should "derate" the transformer (by selecting the correct wire resistance) so no more than 70% of the rated power flows thru it. Also, do not use the lowest setting on the dimmer. It will severely reduce the life of the transformer. A fan "dimmer" used to regulate fan speed is a different type of device and it is suitable for use with a transformer. You still need to make sure it has enough of a power rating.
If you feel any tingling when using electrical power equipment, the rig is unsafe and should not be used until the safety problem is found and corrected.
dude, go to home depot, and get some 16 gauge wire, that stuff wont ever fall apart
Not sure I understand the "downlights"
Would be obliged for further info.