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*
Wire

* 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.

Foam Cutter Power Supply Tutorial

After completing my foam cutting table yesterday, but failing at hooking up the power supply to it, I wanted to get it done to cut some foam.

The Garage of Evil tutorial calls for using a Pony PET-120-12-60 power supply, but no store around here had one in stock. I was going to buy one online, but did a little online searching and found, first, that these are called transformers (I didn't know that ahead of time, and when I tried to explain it to people they had no idea what I was talking about).

Once I knew what I was looking for, I went to Radio Shack and was able to find what I needed: I got a 12.6 VAC, 3 amp power transformer (it was Radio Shack part number 273-1511B).

I also bought a basic dimmer switch from Lowe's:

While the GoE plans also calls for a switch-outlet combination, I didn't figure that was going to be necessary. While I'll get a project box for the parts, the double gang box I originally bought won't fit the RS transformer. I guess that's one of the benefits of the Pony model, it's more compact than this one. But I wanted to cut foam now, so I went with what I had available.

I also bought alligator clips which I connected to 16 gauge wire I had available from my LED light projects.

It was then time to hook up the transformer and dimmer to the plug wire I salvaged from the train transformer. The GoE directions were essential since there are a heckuva lot of wires and no real rhyme or reason to them. Following the schematic, I hooked up all the wires, though I had two yellow wires coming out of the transformer instead of blue. 

Also there were no white wires on any of my components, everything was black or yellow so it was a bit of a guess as to which went where. Maybe it doesn't matter so much. Either that or I guess right. Obviously I bypassed the switch/outlet part.

I connected the transformer to the alligator clips, which in turn were connected to the guitar wire.

Here is a look under the table showing the other connection at the PVC arch:

I plugged in the setup and with fingers crossed I turned on the dimmer. There were no sparks and the circuit wasn't blown so it seemed to be working. A quick touch of the wire showed it was hot, so I shoved some foam into it and success!

I definitely didn't bring anything new to the discussion here, and I suggest anyone looking to build this power supply themselves to follow the Garage of Evil tutorial. It was a big help.

One note of caution: I wanted to see how high I could crank the power on the dimmer and put it all the way up. It didn't take long for the wire to turn red hot and then pop! About half the way provided sufficient power and I sacrificed the wire just to see what would happen.

Foam Cutting Table Tutorial

I spent this morning making a foam cutting table, basically following the design of my fellow NJ/PA Make & Take haunter, hpropman. Joe's design is in turn based on the welded table version made by the Garage of Evil.

I figured I'd offer a step-by-step tutorial with photos for everything I did. The project cost me less than $10, and the most expensive part was the metal bracket, which was about $7 alone. I was fortunate in that I had a piece of MDF already on hand, so if you were to make one too it might cost you a little more for the wood.

This was the quick plans I sketched out on a scrap piece of note paper which I taped up outside my garage where I was working to refer to if necessary. Some of the measurements subsequently changed, but I note them below.

The table started by cutting my MDF to size. I made mine 24" wide by 36" long. While a really big table would be fun, storage is always a consideration and this should handle most projects. Some of the other versions out there use a laminate top because it is super slick and smooth for moving the foam across the table, but MDF is a very smooth surface as well.

I next made two stretchers from 2x3 board I had on hand. The stretchers run the along each long side, though not completely to the ends. I made my 24" long and centered it on the table length, that way if I chose to use a fence to help make straight cuts I'll have a place to clamp it.

I laid out three screw holes centered on the width of the boards (3/4") at 7", 18", and 29". I pre-drilled the holes and countersunk them to keep the screw heads below the table top. When using MDF it is important to pre-drill your screw holes otherwise you're likely (read: guaranteed) to split the wood.

I also glued the strechers to the table top for added strength.

I then clamped the stretcher to the top and pre-drilled it to make sure the screws went in securely (this could have been done all as one step). 

I then screwed the top to the stretcher with 2-1/2" drywall screws.

Here's an end view showing the two stretchers attached.

The next step was to make the arm that holds the cutting wire. I ripped a 2x3 in half, but using a 2x2 would be a good choice, but I was trying to use up spare wood I had on hand. The riser is 22" high while the arm itself is 18" long.

They attach at a right angle with the arm on top of the rise. Once again I pre-drilled and countersunk holes to attach them with two screws. Like drilling into MDF, when drilling into end grain of wood as you are here, pre-drilling is important to prevent splitting.

The next step is to attach a shelf bracket to the arm assembly to ensure it remains rigid and there's no flex that would allow the string to go slack. I used 1" screws here.

To attach the arm assembly to the table, the riser will be screwed to one of the stretchers. An alternative method, particularly for ease of storage, would be to attach the arm assembly using two bolts run through the riser and the stretcher and held in place with either a knob or wing nuts. As I had forgotten to pick up wing nuts, I opted to screw it to the stretcher, though this can be changed at a later time.

As always, the screw holes were pre-drilled and countersunk.

Once that was done, I drilled a 1/8" hole for the wire. It is located 1/2" back from the end of the arm and centered on it. A second hole was drilled another 1/2" back, but this one did not go all the way through the arm as it will be used for an hanger bolt that can be used to keep the appropriate amount of tension on the wire.

An alternative would be to use a guitar tuning key, but my local Guitar Center told me they were sold in sets, not individually, and since I had the hanger bolts aplenty from my LED spotlights project I used them instead.

Once the arm assembly was screwed to the stretcher, it was necessary to locate the hole in the table top so the wire can pass up through the table from underneath. It should be fairly perpendicular to the table so that your cuts are straight.

Initially I was going to use a plumb bob hung from the end of the arm and then measure back 1/2" inch to align the holes. But my daughter came up with a novel, better idea: using the laser pointer on my stud finder. I turned the laser on, shined it down through the hole in the arm, and the laser dot appeared on the table top precisely in line with the hole in the arm. I marked its location and drilled through the table with the 1/8" drill bit.

I had taken a picture of the laser dot marking the spot, but unfortunately it didn't show up in the picture.

The next stage of the project was to make the PVC arch the holds the wire in place under the table. I had 2" PVC pipe on hand, but I imagine 1-1/2" pipe would work too. I cut off a ring about 1-1/2" wide and then cut it slightly more than in half to create tension when it's holding the wire. A 1/8" hole was drilled in the center of the arch.

The wire that I used was 18 gauge nickel wound guitar string. It comes with a ball at the end which is perfect for holding it in place. I got two wires for less than $2 at Guitar Center.

The wire's passed up through the arch, through the table, and through the hole in the arm. I then wrapped it around the hanger bolt to secure it. When the bolt is turned it applies tension to the wire.

At this point, the table assembly is complete.

The next step was to make the power supply, but since that didn't work out so well, I'll save that for another tutorial. My problem was I had attempted to use an old train transformer to generate the heat, but it apparently wasn't strong enough and didn't heat the wire sufficiently enough to cut through the foam. So I will build the power supply described in the Garage of Evil tutorial, but I have to order the low voltage transformer and will show the steps I used when it arrives.

Right now the table looks great and I'm disappointed the train transformers didn't work because I'm itching to give it a go.

Hopefully the steps described and the pictures provided will help you build your own foam cutting table.