Machining PolyUrethane Cushion Foam

Just looking for tips regarding special tooling, feeds and speeds when cutting cushion foam?

I watch @wmoy ‘s video below, but I’m not sure where cushion foam falls in the densities he tests? My assumption is that the pink soft foam is the closest?

Also, winton as well as a lot of other videos on YouTube seem to be concerned with making pockets for tool organizers. A seat cushion would be more likely to have a 3D shape to it which makes me wonder if traditional roughing followed by finishing operations would be a bad choice VS just going aggressive with a 3D parallel tool path?

The big problem in my experience is the stuff getting wrapped around the endmill interfering in cutting.

Amana makes special endmills for foam cutting which I’ve been meaning to try.

Is a drag knife an option?

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no, I do not have one, but even if I did I’ve never seen a drag knife that can do 3D shapes?

Not an option then — a drag knife can only do 2D outlines.

Can you configure a “hot” knife?


Sure, is that really going to be easier than getting the right cutter and learning how to cut it?

Carving out an imprint of butt cheeks with a DIY version of a hot knife seems like it might take some skill/practice.

There are CNC controlled hot knife setups — there are some pretty cool videos on YouTube, &c.

I mislike the idea since the smell/fumes give me a headache (too much plastic model-making when I was young).


Eventually, you should see how the prop/model makers do it. They’re always creating those full-chested props for stage and show.

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