Wednesday, May 18, 2011

Handheld Foam Cutter Tutorial

The latest addition to my hot wire foam cutting tools is a handheld device for when I want to do close-up work and don't need the table. Detailing the edges of tombstones, for example, or carving out pieces of foam that might be too awkward for the table to handle are the instances where a handheld foam cutter would be handy.

While initially basing my handheld cutter on a device hpropman made, this one is much smaller than his as I envisioned using it for the times I mentioned above. His cutter was about a foot or more in width; mine is about 6 to 8 inches.

To make the cutter, I used scrap 1/2" Schedule 40 PVC though I imagine other sizes would work, as would thinner Schedule 20 PVC. The parts list for my device are as follows:

Handle - (1) @ 8"
Cross bars - (2) @ 2"
Arms - (2) @ 4"
T - (1)
90 degree Elbow - (2)
End Caps (3)
Nickel wound wire 18 gauge
Screws (2) @ 1"
Nuts (6)
Washers (4)
Wire Connectors*

* I'm not sure exactly what they're called. They're circular and allow you to insert a wire into the end which you're then able to fit over a screw.

After cutting all the pieces to length, I dry fit them together. Actually, I didn't glue up any of the parts because I figured there may come a time when I want to swap out the parts for wide or longer pieces, depending upon what I'm working on, and rather than building a whole new cutter, I could just remove whatever's in there currently and replace it with the new parts. The caps definitely shouldn't be glued because you may need to gain access to the nut holding the screw in place.

This is a really quick project, the hardest part being fitting my fingers in the end caps to tighten down the bolt. Here is a picture of the end cap assembly showing the screw, two nuts, wire connector, and washer. As you can see, I drilled a 3/8" hole in the top and side of each end cap. The top hole is obviously for the screw; the side hole allows the wire to travel down inside the PVC.

I wrapped the 18 gauge nickel guitar wire below the top nut and tightened the nuts down. I stretched the wire across to the other side and did the same thing. Since I couldn't show a picture of the completed end cap assembly underneath that would have any meaning, below is a drawing of how the assembly looks.

One adjustment I may look at making is coming up with a way to fine tune the tension on the wire because when it heats up it does stretch a little. But in the meantime it works just fine. I also noticed I didn't need nearly as much power with this device as I did with the table. Or rather, I noticed the wire actually turned orange on the handheld at the same setting it was on for the table. Perhaps it has to do with the shorter distance between the wire, or maybe it's that I'm using 14/2 Romex wire compared to the 16 gauge wire I used for the table that I had left over from my LED spotlight project. Either way, I dialed it back before I snapped the guitar string.

With the hot wire handheld cutter and foam cutting table, I think I should be able to tackle any of the foam cutting projects I have in mind. I do have a tendency to build jigs and tools to help build projects without building any project itself! At least now I don't have an excuse for not working on props.

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