I recently started working with foam and decide to make a foam cutter. There isn't much that is new about my foam cutter but I did some things differently than the others that I had seen and thought maybe someone could use that information.
List of materials I used...
1 piece of 1/2" Micarta 20" X 20" square
1 piece of metal tubing about 22.5" long. OD: .250, ID: .166
2 2X4 boards 20" long
2 pieces of 16 ga wire 3' long
1 large grounding lug
1 small grounding lug
1 .015 guitar string
2 ring style wire connectors
4 cable nail clips
2 small screws
2 small nuts
4 wood screws
5 self tapping screws
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Step 1: Work Surface
I made my work surface out of a 20" X 20"piece of Micarta. It is smooth and has good heat and electrical resistant properties.
I drilled a hole in each corner so that I could secure the 2X4 boards with four screws. This elevates the Micarta allowing space for the wires underneath. In the center I drilled a hole for the wire to pass through, then I mounted the small grounding lug so that the hole in the lug lined up with the hole in the Micarta. Then I used a self tapping screw to secure the lug and one of the wires (with a ring connector) to the underside of the Micarta.
Step 2: Upper Wire Armature
For the armature I use a piece of tubing. I wanted the wire to be hidden and out of the way.
I bent the tube to 90 degrees about 9" down from the top.
I then drilled a .250 hole in the Micarta base for the tube to go into.
Using a Dremel tool I cut a small trough for the wire to lay in when the base was on the bench.
I fitted the tube into the Micarta and set the height to where I liked it, mine ended up 11" off the top of the work surface.
I drilled and tapped a small hole for one of the screws and tightened it against the tubing to hold it in the Micarta.
Step 3: Wiring
As stated before, I attached one of the wires to the lower lug, then I fed the other wire through the tubing with the other ring connector at the top of the armature.
I slid on a piece of shrink insulation over the end of the tube and slid the large lug over that. I then slid in a small bit of Teflon between the insulation and the lug screw so, that when tightened down, the lug screw would not cut through and make contact with the metal tube.
I added a plate left over from a project box to protect the wire in the trough using four self tapping screws.
I then nailed in four cable nail clips to the underside, inside of the rear 2X4 board and ran the wires through to the outside of the base.
I then attached banana plugs to the ends of the wires for plugging into my DIY power supply that I built using this instructable "Convert an ATX Power Supply".
Step 4: The Guitar String
Guitar strings come with a small brass ring at one end. I used this to hold the string in after it was fed through the bottom lug.
using the other screw and one nut, I fastened the upper wire, using a ring connector, to the lug
Then strung the guitar string around the screw and between the two washers and used the remaining nut to capture the string and keep it tight.
Step 5: NOTES
The guitar string: I searched all over for which guitar string to use. Out of a set, there are three that are solid and not wound. a .010, a .013 and a .015 (listed on the package as .017). I tried the High E or .010 first and it did not last long. The .015 seems to work very well and at two different voltages. I measured the resistivity of the three strings and they were .010 = 1.2, .013 = 0.8, .017 = 0.5 per 12".
Voltages: I am using a ATX power supply as the power for this cutter. The 5 Volt output for slow detailed cuts and 12 Volts for quick cuts.