Milling Plastazote LD33 closed cell Foam - Any milling advice?

**Zeeflyboy** · 06-03-2017

It's got good structure but somewhat soft and giving if you squeeze it... Nothing like a rigid insulation foam, and it bounces back rather than crushes. I believe that it's a type of polyethylene foam which is available in various densities - this one is 30kg/m3

It's actually two sheets - one 30mm yellow and one 5mm black. The plastazote stuff is available in black, white, red, blue yellow or they have some cheaper similar foam in black and white only. You can then heat weld them together (carefully!) using a hot air gun to create the bi-colour piece.

I've managed to find some clean looking machining of similar looking foam where they were using single flute down cutter, so i've ordered two of those (a 3mm and a 6mm) to have a try with.

**Zeeflyboy** · 10-03-2017

Right, nailed it I'd say!

The below is using a 6mm single flute down cut bit (belin). Conventional rather than climb, 16,000rpm, 3000mm/min feed rate and 15mm step down (except the test collet cut out was done with a ramping helix to get the wall angle smooth).

Came out nice and clean - now I'm happy to move on to actually making the proper inserts.

**Zeeflyboy** · 11-03-2017

Well, milled really nicely but It was stuck down too firmly and i couldn't pull it off the bed without ruining the foam

At least I have some spare material.... sigh

**Zeeflyboy** · 26-03-2017

Quick video of milling this stuff:

What I learned in case anyone is interested in having a go:

- When making multi layer stuff, it's much easier to use 3M super77 spray glue to stick the layers together... that is the glue that my research turned up and you can get it in this country for a fair enough price from farnell. While heat welding works, I found it quite tricky to get the right balance between hot enough to get a good weld and not too hot to deform or damage the foam.

- Down cut router bits are definitely the way forward, gives a much cleaner edge.

- Never climb! Conventional milling all the way.... climb gives a truly awful edge finish.

- If you ever get any foam stuck on the bit, hit feed hold immediately and clear it off... it can very quickly give you a fuzzy edge cut.

- Fast feeds are good, but single flute cutter is quite happy whizzing through at around 3,000mm/min or even less which is well within the reach of most machines.