This hot-wire cutting jig is meant to cut long and even blocks of different but precise size. I made this to make the blocks that go between the studs in the walls of my garage\workshop because I was tired of the mess that cutting the blocks made (that and the problems uneven snapping caused).
I must credit http://hotwirefoamcutterinfo.com/Introduction.html for much of the information that allowed me to build this.
Step 1: Parts and Tools
You will need:
- Drill (and maybe use the same battery!)
- Bits (1/4, 5/16 and 5/8)
- screw drivers
- Soldering iron (I use a butane iron, much better)
- power supply for your cutter (see my instructable on the topic here https://www.instructables.com/id/Hot-Wire-Cutter-Battery-Power-Supply/ )
- 5/8 dowel
- wood screws
- 1/4-20 machine screws/bolts
- 1/4-20 t-nuts
- wiring (I prefer using extension cord wiring for its flexibility, I find it to be best value; silicone sheeting wiring would be even better, but it is more expensive)
- tin for soldering
- nichrome wiring (I used 26 gauge)Anderson connectors (optional)
- 1/2 inch copper plumbing pipe (2x the length you are aiming for + a bit of extra)
- 2x female-female copper coupling fitting for 1/2 inch copper plumbing
- 2 small self tapping screws
If you want to make a static jig (non adjustable, but more reliable), you don't need the 1/4inch stuff, or the dowells)
Step 2: The Arms
- The copper arms are cut to length. Copper is used as it will conduct the electricity to the nichrome wire, but also to act as a heat sink for prolonged use of the cutter.
- if you want a non-adjustable version, this is where this steps ends
- At the end of the pipe, the coupler is soldered in place, and the dowel is inserted in the other end of the coupling. The reason for this is to be able to serve as a handle, but also to prevent the arm from being crushed when the bolts are tightened.
- The wiring is soldered to each arm and the connector added to the other end (if you are using some)
- I then drilled a 1/4 inch hole through the coupler. It is important to be drilling through the wood as well, this is important for the structural integrity of the device.
- In order to prevent the arms from moving independently, 2 extra bits of dowel are cut to the same width as the spacer block, and are used to make the handle / join the two arms on the dowel side
- This is where the wood screws come in handy!
Step 3: The Base
The base should be the width of the edge along which you will be running the block to properly space the 2 arms of the cutter. In my case, it was a piece of 2x4.
I simply drilled a 5/16th hole all the way through to have both arms aligned, and inserted the 2 t-nuts.
For a non-adjustable version, instead, drill 2 5/8ths holes spaced as you want it in which you can put the pipes to hold them.
Step 4: Assembled Structure
- The 1/4 inch bolts are used to secure the arms to base/spacer block we prepared earlier.
- The nichrome wire is attached using the self tapping screws at the end of the arms. Wind the nichrome around the screw and tighten to finish up the tension setting.
Step 5: Height Adjustment
Now I went all out and added a laser pointer to know what height I am at, but really a pencil mark on the arm will do. As you fold the device in, the gap will get smaller, measure the space from the wire to the base, which acts as a parallel reference face, measure the distance and write, on the base, what the corresponding height to the angle is. This way you can make quick adjustments.
Step 6: Use It!
Use it! The video above demonstrates my two types of foam cutters used according to their strengths.