Techniques and advice for modifying the shape of foam and other materials.
Cutting & Carving Foam with Knives
Cutting Against a Straight Edge
Creating an Improvised Fence
A top-down diagram of a straight edge clamped to a
cutting board over a sheet of foam.
Key: Grey, Cutting Board; Blue, Foam; Black, Ruler; Red, Clamps.
Cutting Foam Freehand
Carving Foam
Cutting Foam with a Band Saw
Shaping Foam with a Router & Router Table
Shaping Foam with a CNC
Cutting and Shaping Foam with a Hot Knife
Shaping Foam with a Bench-Top Grinder
Shaping Foam with a Dremel
Cutting Cores & PVC to Length
Tape is Your Friend
A wrap of tape around the spot that is about to be cut, even if just on one side of the kerf of the blade doing the cutting, can help mitigate any chance of splintering.
Don't Cut All the Way Through
Try to always be cutting towards the center. Once you are most of the way through the rod/tube, roll it 180 degrees and cut from the other side. Cutting 'out' from the center and breaching the surface can cause problematic splintering, even with tape present.
Hand Saw
Hand Saws are a bit tedious for solid rods, but tend to make quick work of hollow tubes. Focus on making long, straight, strokes and don't put too much weight on the core as you saw. Make sure to flip before you get all the way through, as this is the most prone method for splintering from that.
Dremel
Using a cut off wheel attachment, it is easy to make quick work of cutting through both solid rods and hollow tubes. Dremels will throw a lot of dust when cutting solid rods. Bear in mind that you'll also likely be cutting at a slight angle, so the cut will need to be cleaned up after you've separated the offcut from the "keep" section of the rod/tube. As this approach is grinding away material abrasively instead of using a saw blade, it is the least likely to cause splintering when done well.
Band Saw
Like the hand saw, but without the manual cutting. If your blade is dull, this will not go well. This will also dull blades quicker than cutting foam or wood.
Miter Saw
A quick and easy way to cut cores in batches or by themselves. Make sure they are well taped to prevent splintering and make the cut with smooth motion rather than slamming the blade through the material as it spins to prevent splintering.
