Build Your Own Hot Wire Foam Cutter at Home.

Foam board, in many forms, is in common use on model railroad layouts. Effective use of foam can allow for scenic contour that provides both firm support and realism to your layout.

Effective cutting of foam can be an entirely different matter. Mess, irregularities and impatience can make cutting foam into a chore, at least for me.

A hot wire foam cutter can cut foam cleanly, quickly and smoothly, and it can be done with minimal cash outlay. I did it and so can you!

A hot wire foam cutter can be built from material that may be laying around your home or garage. Combined with a few items purchased from any hardware or building supply store, you can have the finished product in a few short hours.

Materials:

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 Small pieces of wood (ie. 1X2 pine)    

Plywood                                              

Wood screws                                      

Electrical cord                                      

Eyelets                                               

Doweling                                            

Wire (ie. galvinized steel or nichrome)

Old model train transformer               

Alligator Clips                                    

Tools:

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Drill                                                    

Plyers                                                

Screw Driver                                      

Saw (electric or otherwise)                

Wire Strippers                                   

Elbow Grease and a little patience    

Disclaimer:

Working with tools requires safe practices. Ensure that you are familiar with the operation of your tools. Utilize proper safety equipment (ie. Safety glasses, gloves, etc). If you are a minor, please ensure that you have parental supervision or permission before beginning. A completed project is always more satisfying when it is completed without injury. Also, as this project involves electricity, remember that it is dangerous and can shock, burn and cause death if not used properly.

As the old saying goes, there are a thousand ways to skin a cat, this is just one. You can use many variations and achieve the same result.

The Build:

I started with the base. I wanted it to be strong and level to provide a firm work surface. I used several short pieces of 1X2 pine that I had laying around.

[G2:50007]Fig.1

[G2:50010]Fig.2

Figure 1 shows the front of the base to the right of the picture (figure 2 shows the front to the left.)

I laid two feet, 16" long and 8" wide, from the outsides of the feet. On top, I laid out a box (fig.2). At the back of the box, the pine stands on its narrow side. This is where you will later attach your upright bracket. The pine at the front is laid flat, This will allow you to screw in an eyelet to which you will later connect your galvanized steel wire. I drilled small guide holes and screwed it all together with 2 1/2" wood screws.

[G2:50019](Fig.3)

Next take your bit of plywood, the size of which really depends upon your personal preference, and place it on top of your base. I used an old shelf out of a computer desk that was slightly wider than the base and about 20" long. I wanted a bit of length so that I could cut larger pieces without difficulty.

Determine how your plywood will sit on the base and mark out guide holes for screwing it onto the base. You will also want to determine where the eyelet  on the front of your base is in relation to your plywood so that you can drill a larger hole directly above the eyelet. This is where your hot wire will run through your base up to the bracket. Lastly, you can cut a hole in the back of your plywood to allow the bracket to pass through where it will be affixed to the back of the base. You can also have your plywood flush with the back of your base, in which case you wouldn't need a hole at all. Screw the plywood onto your base.

To build the bracket, I used a metal shelf bracket for support, which I purchased at a local building supply store for about $3. I used some more of my 1X2 pine to give the bracket some substance, drilled a hole in the end of the upper arm of the bracket and inserted a short piece of 1/2" dowel. I screwed another eyelet into the end of the dowel. This is where your galvenized steel wire connects at the top. Height and depth of your bracket are a matter of personal preference. Just ensure that the end of the top of your bracket lines up with the eyelet in the base of your cutter. You want your wire to be perpendicular with your cutting surface to give you straight, even cuts. (Fig.4)

[G2:50022](Fig.4)

Now you can attach your bracket to your base. I recommend screwing it to the back of the base. You may notice from my pictures that my cutter appears to have a pivot where the bracket attaches to the base. I was trying to be fancy and have an extension spring underneath to help keep the tension in my cutting wire. Didn't work out that way for me. I ended up removing the spring and attaching the bracket permenently to the back of the base. The spring was attached to the eyelet in the end of the bracket top.

[G2:50025](Fig.5)

I had some old cord laying around, left over from some lamp fixtures I installed. I took this and seperated the two wires. I attached alligator clips to the ends of each. One wire runs underneath the base to the eyelet in the front. The other wire I ran up along the bracket so the the other alligator clip is near the spring at the top. The alligator clips I got at a hardware store for $2.

I then took a piece of galvanized steel wire (you can use nichrome wire, too), attached it to the eyelet under the plywood, ran it up through the hole in the plywood and attached the other end to the spring on the end of my bracket, making sure that it was reasonably taut. The alligator clips where then clipped to the wire at either end. I bought a whole roll of galvanized steel wire at the hardware store for $5.

[G2:50028](Fig.6)

The other end of the electrical cord I connected to an old model train transformer I had. This is handy because the transformer already reduces the voltage to safer levels and allows you to control the output. Figure 6 shows a Tyco transformer, I actually used a Marx train transformer. Once connected, you need only turn the throttle up until you can hear the wire hum or the wire will easily cut through foam. Too much and the wire will snap or it will overload your transformer. Slow and steady wins the race here.

If by some chance you don't have a spare train transformer, you can buy a single pole light dimmer switch and a transformer unit in the electrial section of your hardware store. Connect a plug in to the dimmer, connect the dimmer to the transformer and then the transformer to the wires running to either end of your hot wire. Use care if you intend to do this as you will have connections with 110v, a dangerous amount of electricity. Ensure your connections are secured, taped with electrical tape and housed so they can not be touched inadvertently. A dimmer and transformer would run between $15 and $20.

Now your done!

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Now you can cut foam quickly and safely with your stationary Hot Wire Foam Cutter. With the left overs of several home projects and $10 out of pocket, I was able to build mine.

Have fun and good railroading.

Cheers,

Jim R