THE GUILLITINE AND THIN FOAM SLICER
Here is a simple, inexpensive, safe foam cutter you can make and use that really works. By Lee Aston
The guillotine is a frame that guides the cutting wire in an accurate vertical cut. It uses the bow which has already been described. The bow is still suspended by the rubber band chain from the ceiling. It is used for cutting the foam sheet into usable blocks. It trims trailing edges perfectly. It can also make thin foam sheets. I use this tool on every wing I cut.
The guillotine uses 4 flat "L" corner brackets stood back-to-back and screwed into a wood base to guide the cutting wire in a vertical cut. This cutter is designed so the cutting wire drops through the foam and into a slot in the platform so the foam can be removed with the hot wire out of the way.
The guillotine also will cut thin sheet slices out of thicker foam. The same corner brackets that control vertical cuts keep the wire from moving horizontally. The wire can be accurately suspended any distance you want off of the table and it will slice thick foam into thin foam sheets by moving the foam through the cutter like a table saw. I can cut EPP thin slices any thickness I want.
I set the depth one of two ways. I can raise or lower a flathead screw that is just inside the corner brackets and the wire sits on the head of the screws; or my favorite: I put a piece of brass tubing the thickness of the foam I want on each end of the base and it sets the thickness of the cut.
I have one guillotine that uses 6" x 6" flat corner brackets and my favorite guillotine that uses 12" x 8" carpenter framing squares. The 6" brackets cost $1.00 each. The carpenter squares cost $5.00 each but the 12" carpenter squares give you the ability to store the bow between cuts by setting it on top of the squares while the 6" does not. To me it is worth the extra cost.
You do not need to have a large platform on the guillotine. A smaller platform can trim trailing edges and chop blocks of foam. A large platform is helpful if you are going to cut more than one wing and you want to put jigs on the platform so you do not have to measure each cut. A big base is also helpful if you are going to make thin slices of EPP for thin foam planes.
The squares are made of metal. Metal carries electricity. You need to electrically isolate the brackets or squares by covering them with clear or duct tape except for on the edge that touches and guides the hot cutting wire so there is little chance of you making electrical contact with the cutting wire.
The construction described is for the large cutting platform with all of the bells and whistles.
HOW TO MAKE A GUILLOTINE FOAM CUTTER
1. Cut three 24" pieces from a straight 2x4.
2. Using a flat ¾ particle board, cut a 38" x 15.5" and a 38" by 8" cutting platform. (If this board is warped and you use it for slicing thin sheets of the foam, the foam may be thicker at the ends or in the middle.)
3. The 2x4s will be positioned north/south while the platform pieces will be positioned east/west on top of the 2x4s with one on each edge and one in the middle.
4. Leave a ½" gap between the two platform pieces. This gap is where the cutting wire goes and hides after it passes through the foam.
5. The corner brackets will sit on top of the 2x4s next to the sides of the particle board platform, so leave the side 2x4s ¼" wider than the platform.
6. Drill pilot holes, countersink the heads of the screws, and attach the platform to the 2x4s.
7. Drill holes in the carpenter's squares on the 8" side to screw the squares to the side of the ¾" thick platform.
8. Put a layer of clear plastic tape or duct tape on the metal squares to prevent electricity from being transferred to you. Cover the entire square except for ¼" along the edge of the square that touches the cutting wire.
9. Center the squares so the cut occurs in the middle of the ½" space between the two platform pieces.
10. Set the squares on top of the 2x4s and next to the sides of the platform.
11. I use a piece of Formica to set the gap between the carpenter squares so there is enough space for the wire to travel without binding.
12. Screw the carpenter's squares in place.
13. Screw a flat head screw it to the slot near to the gap between the squares to keep the wire from dropping onto the wood 2x4s. Leave the screw up about ¼". This is the screw that you can raise to set the thickness for the thin sheet foam cuts.
I hope this information will be helpful. I am a hobbyist not an electrician or an engineer. What I am going to tell you is the way I have made my foam cutter work for me. There are many other good ideas out there and I encourage you to seek out other ideas and methods to make your foam cuts as safe and precise as you can.
