DIY Hot-Wire Foam Cutter

The file downloads have a few small improvements above the cutter that’s pictured.

Here’s the “One-Nite” DIY Foam Cutter. It took one work session (one night) to design and assemble. I was surprised how easy and fun cutting foam is. 

I designed it using Sketchup and used a desktop CNC (with SketchUCam) to make the parts.

Here’s my desktop CNC cutting business cards from LP Records. A CNC laser is a great way of cutting parts too (my laser).

The entire frame is made from the same material to simplify the bill of materials and tooling.

One-Nite Hot-Wire Cutter Specifications

Power Supply: 9VDC, 500mA
Cutter: 40 gauge nickel chromium
Current : ~220mA
Z-Axis: 4.5″ fence
Cutting Table: 8.5×11″
Format: Vertical cutter with removable fence

Make It

Cut the parts out and make this frame.

I chose 1/4-20 bolts since I had them on hand. You could use any nuts and bolts. Don’t forget to adjust the hole sizes though.

Bill of Materials:

  • Couple sheets of 24×24″ hardboard
  • Three 1/4-20 bolts about 2″ long and about 6 nuts
  • Two wing nuts (or regular)
  • 40 gauge nickel chromium wire
  • Rubber bands (#10 or #12)
  • Two alligator clamps
  • Glue (wood glue, white glue, etc.)
  • 9V 500mA power supply
  • Styrofoam. Work in a ventilated area since some foam gives off poisonous gasses when heated.

Nickle chromium wire installation.

It’s way too easy. Cut out the parts from 1/8″ hardboard. Wood glue them together, add the three 1/4-20 bolts with nuts.

The top bolt (right) is locked in place with nuts and the nickle chromium wire is locked to it with nuts. The wire is fed through the hole in the cutting table, wrapped around the lower bolt and attached to the last bolt using a rubber band. Attach the wire to the elastic by looping the wire onto the elastic and then spinning the elastic to twist the wire. The last bolt can be made shorter so its easier to loop the elastic on.

Electrical is clamped to the bolts with alligators. Here’s how I chose a 9V supply. Using a lab supply I set the current limit to 150mA and increase the voltage until the wire cuts nicely. Note voltage and amperage and choose a supply that matches the voltage but has about twice the amperage. 

The fence is held in place by clothes pins (there is a 1/4″ overhang of the cutting table). Very adjustable.

Frame: simplecutter014

Fence: simplecutter015Fence 

Foam Slicer

Here’s a design for just slicing. Bolts will point up from those holes and you can span them with nickle chromium wires. The cutters run along the surface. Use the bolt threads to help align the wires so you can “multi-slice” the foam.

I’m wondering if 1/8″ is enough room for nuts which would be on top of the holes.

I made three hold sizes so different bolts can be tried (1/4″, #8, #10 and #12).


Hot Wire Cutting Bow

I had some extra hardboard left over from the projects above so I used it to make a 10′ cutting bow. It accepts a pair of 1/4-20 bolts so you can wrap the cutting wire around it with an elastic. Here’s the sketchup file: HotWireBow

Foam Slicer In Action

I’m getting geared up for another foam glider blitz so am running my foam cutters. Here’s what it looks like!



A robotic version of the cutter.

Use this cutter to make a cool Valentines card with a flyer inside.

Make up some flyers and have a party!

Phil Rossoni makes a Tyler McCready design using this foam cutter!


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