Introduction: Hot-Wire Foamcutter (Battery Powered)
I have a hand-held battery powered foam cutter (these can be found at any hobby/craft shop). I find it quite useful, however I'm quite often frustrated by its inability to do detailed work. This instructable is simply a tabletop flat bed version of this handheld unit.
-Makes detailed work easy.
-Inexpensive (only a few dollars in parts)
-Small (easily storable)
Lets get started;
Step 1: Parts & Tools
Here is a list of the parts I used. Many of these can be replaced by easier to obtain equivalents, or cheaper options.
(also the metric components can be replaced with their nearest imperial counterpart if you are in Canada or America (M5 = 5mm ~= 1/4")
Parts: (Approximate cost $15)
-Bolt (M5 x 30mm) x 2
-Nut (M5) x 2
-Washer (M5) x 3
-Bolt (M3 x 15mm) x 2
-Nut (M3) x 2
-Washer (M3) x 3
-Nut (M20) x 4 (these are used as legs to lift the board off the table so 4 chunks of anything about 15mm tall will work)
-Nichrome Wire (can usually be found at hobby shops beside their foam cutters as a replacment part)
-Battery holder (2 x AA)
-Small Cutting board (mine was 16cm x 26cm)
-Wire (about 40 cm)
-~40cm of 4mm diameter metal rod
-Hot Glue Gun
-Soldering iron (I used a soldering iron to melt the holes into the cutting board this is because I did not have access to a drill)
Step 2: Hole Drilling
There are only three required holes.
I used a hot soldering iron to melt through my cutting board.
The middle hole has a 3mm hole drilled through and a 15 mm wide and 5mm deep depresion made around it. (this depression is to allow the bolt holding the bottom of the hotwire to rest flush with the cutting boards surface)
Below is a picture showing the hole layout.
Step 3: Bar Bending
Bend the bar so it has two loops large enough for a 5mm bolt to go through. One at the end and another 50mm in (these will line up with the holes you just drilled). Next bend the bar so it goes up for 10 cm, then over for 10 cm and then another loop bent onto the end. Precision is not particularily important as any small misalignments can be sorted out after assembly
If that writeup was a little vague (I certainly found it so) please find attached a drawing as well as a photo of the finished piece.
Step 4: Adding Feet
Glue the four large nuts to the bottom of the cutting board.
This provides clearance for the wire which runs beneath the board.
Step 5: Wiring
Two elements here.
Wiring the battery holder:
Attach a length of wire to each the positive and negative terminals of the battery holder. One length of wire needs to be long enough to reach the hole in the middle of the cutting board. The other needs to be long enough to reach the hole in the top corner of the board. (I attached washers to the end of these wires to make attaching them easier, I put a large washer on the shorter length and use it as a simple on off switch)
Wiring the hot-wire:
The required length of hot wire (nichrome) will vary depending on the type you have. Experiment with different lengths and 3 volts, use a length which produces a dull glow but does not cause the wire to melt. (takes a little trial and error)
Once you have the appropriate length figured out. Add a washer to both ends of it, twisting the wire to keep it connected (as in the photo)
Step 6: Assembling / Using
Time to put it all together.
1.I glued the battery holder close to the top corner (granted this did cut down on my cutting freedom so relocating this may be a good idea)
2.Attach the bent rod using the two 5mm x 30mm bolts to the two holes drilled into the top right of the board.
3.Run the long wire beneath the board to the hole in the middle of the board. Run one of the 3mm x 20mm bolts through one of the washers at the end of your hot wire length. Then feed this bolt through the hole, attaching the wire to the bottom and fixing it all in place with a nut.
4.Taking the free washer end of the hot wire, run the remaining 3mm x 20mm bolt through it. Next run this through the end loop in the bent rod, using the elasticity of the rod to pull it taught.
5.Use, attach the short length of wire to the 5mm x 30mm bolt and cut away.
Hoping that was helpful if anything is unclear (my wording can be rather cryptic at times) please feel free to ask any questions in the comments and I'll do my best to answer them.