Cutting EPS Foam

[Hobodog2]

Anyone have experience cutting white R-Tech® brand expanded polystyrene (EPS) (from Home Depot).

What type of bit and what speeds and feeds do you recommend pls?

Thanks, Pete

[mikeacg]

Pete,

Haven't seen the white stuff yet! What does it cost a sheet?

[Hobodog2]

Mike

Well, I bought 1" thick, 2' x 4' sheets for $2.98 each. I don't recall pricing on the other sizes, but it was comparable to that line of pricing.

I ended up using a table saw to make some cuts and the laser engraver to make the more detailed cuts - both worked great, nice and smooth and straight.

The laser tends to make a tapered cut due to the laser beam diverging as it goes through material.

Pete

[jsooter]

EPS foam is often cut with a hot wire. I don't know if that helps you though

[mikeacg]

Pete,

I've been playing with 2" Pink EPS foam for the last month and it cuts like a dream though it tends to warp up as you cut out sections. I put carpet tape under the middle along with screws on the edge and that helped alot.
I'll run over to HD tomorrow and grab a hunk of the white stuff and give it a shot. I'm redoing my entryway in 3D foam and 1" would be perfect - especially at that price! If it is anything like the pink, you can run the heck out of it. I cut the last pieces at 6 IPS and I know I could go faster.

[Mayo]

If you don't mind that the edge will have uniform lines going parallel to the face of the material, you can use a RotoZip tile cutting bit.

Depending on the foam, you may have to adjust your cutting speeds.

The pink foam will melt onto this bit if you either cut too slow or have your router speed too fast. I cut pink foam at about 1.5 inches per second but I almost never buy it any more because I don't want to deal with the printing on the surface. In addition, all the sizes from 1" and thicker now are only available (around here) in sheets that are scored almost half way through on both sides to make it easier for contractors to snap the sheet into pieces at 16, or 24 inches. The blue foam has similar characteristics but it's a softer, less brittle foam compared to the pink - which isn't pink any longer by the way. Around here the pink foam is now mauve color.

I now buy 2lb density white foam exclusively - from out of state, and the difference between it and the local H.D. **** is amazing.

I usually cut this white foam at about 2 to 2.75 inches per second depending on the thickness of foam and how detailed my parts are.
Router speed is at my lowest setting of 10K.

On thicker foam - 1 1/2 and 2 inch, I have successfully used the normal RotoZip bits. I like that the bit is 1/8" so I can get relatively tight inside corners on letters. The bits do have some flex to them, so you may get a stepped look on the cut edge if you cut too deep per pass, or your move speed is too fast.

For hold down, all I use is 3M Super 77 Spray Glue. A light mist on the foam is all I need to keep it in place. I do not put the spray glue on my spoil board - which is also foam. Let it tack up for a couple seconds before putting it sticky side down onto the spoil board, and then FIRMLY using both hands over the entire surface, apply pressure to bond it to the spoil board. You'll know if you used too much glue when your foam refuses to come off the spoil board except in little chunks. I sometimes have to lift my parts slowly and carefully to avoid breaking them but it's cheaper than a vacuum system and because every job I do is totally different from one to the next, a vacuum jig or plenum for me isn't worth the time to make it. If I was doing the same parts repeatedly - in quantities of hundreds or thousands of pieces, it would pay off but most of my orders are for quantities of between 1 and 24 pieces.

[mikeacg]

Mayo,

Where do you get this 2lb density white foam (if you don't mind sharing your secret...)? I'm really getting into cutting foam lately but I would love to find better pricing!

Mike

[Mayo]

Hi Mike

Check your messages - info sent.