Pink Foam

[waltie]

What is the best RPM & feed rate for cutting
pink insulating foam? Thanks

[billp]

Waltie,
You can blast through the material at just about any speed you'd like due to it's softness, porosity, etc. I would usually run a 3"long, .5" ball nosed bit at 10 IPS with an Alpha, and I got great detail.(I think I could have gone faster, but didn't see the need to).
Your major limitation for getting crisp detail will be the method you use to hold the foam down with. Since I was running larger pieces ( 5 feet long, and 3"deep) I chose to use drywall screws with washers on them, but on smaller jobs a Fein vacuum worked just as well.
I ran both PC router and Colombo spindle close to 10,000 RPM and got a clean (for foam) finish with no burning or tear out.
PS- You might want to get a box of "Bounce" anti static laundry sheets. They DO help to prevent static buildup as your machine is cutting, and this means you/your machine won't wind up wearing a lot of pink fuzzy foam dust around the neighborhood.

[harryball]

Bill... what do I do with the laundry sheets? Rub down the machine or stick one in the dust collection hose?

Robert

[waltie]

I will be cutting out large letters for a sign company. I was thinking of using a 1/4 upcut bit. the foam is only .780
would 8ips at 10,000 RPM give me a good finish
with no melting?

Thanks, Waltie

[Brady Watson]

Waltie,
I don't think that I've ever seen the insulation type foam melt. You'd have to be doing something really wrong for it to melt.

The biggest issue with the foam is, as Bill said, holding it down. You CAN blow thru the stuff pretty fast, but you need very sharp tools to do so at high speed. If not, the bit will pull out chunks of foam rather than cut it clean. I'd try running at 3-4IPS 1st, and watch the effects of cutting. If the foam starts moving, you need to reduce the speed, increase RPM or reduce your stepdown. Depending on the design, you'll have to set your speeds accordingly.

Robert,
Rubbing the surface of the foam with a dryer sheet will help reduce static cling. StaticGuard spray works for a few minutes and peters out. Keep a keen eye out for the foam flying in the air and sticking to your gear rack on the Y axis (foam & gear racks have a strange affinity for one another) since build-up in the teeth of the rack can cause positional loss as the pinion runs over large chunks of foam mashed into the rack...

-B

[billp]

The Bounce sheets also work very well for wiping down the gantry after cutting foam for a long period of time. Anyone who has cut lengthy files in styrofoam will probably agree that it is incredibly tenacious, and pretty tough to "corral" once it's been shredded into small particulant form.
As Brady points out above, I don't think I've ever seen the foam "melt" from cutting, (usually that's a process reserved for the first time someone tries to coat it with a solvent based finish, and then you get a real mess.....)
If your letters are flat or slab sided the up cut bit should work fine, but if there are any rounded sections, you might see some tendency to tear out in spots. Then a ball nosed bit might be a better choice.
Generally speaking it's a very forgiving (albiet sloppy) medium to work with and a GREAT way to test new software, techniques, or files....

[paco]

My success with extruded styrene foam (up to 2 inches thick) is with a 1/4" CED 2-1/8" CEL spiral up solid carbide at 1.7"/sec. (max) and 16 000-17 000 RPM at a single pass cut.
Anything out of those spec. as gotten me with less than desirable edge quality. I can cut it way more faster but with a very teared out edges.

When I cut very small letters in 1 inch thick I use a 4 flutes instead of a 2 flutes at 18 000 RPM and 1.7"/sec. for good edge quality.

I would pay if someone could show and prove me that he can cut it with good edge quality at say something above 4"/sec. Challenge up; I'll be asking for details...
I spent days testing to improve both edges and process speed. Sign people want nice letters so I cannot delivers rough edges.

I did melt styrene foam with HSS tooling and 4 flutes 1/4" CED 2" CEL.

Carving is an whole different story because the kerf has room for the "chips". I don't have any problem carving extruded styrene very fast...

[joe]

Paco my friend,

Have you tried a foam board sold as "Ultra Board"? It seems to carve at speed leaving very clean side walls and razor sharp edges. We just love this procuts for cut out lettering.

This is a white laminated forambboard. Styrene surfaces with EPS interior. It comes 1/2" to 3" thick. There isn't any need for sanding or filling. She's ready for paint when routed. I'd put the cleaness of cut up against HDU. To me the interior of Ultra Board looks and feels close to insulation board, but not quiet. The weight is close to the same.

Since Ultra Board has a hard first surface there isn't nearly as much static cling as blue and pink foam. That stuff is off limits in our shop.

http://www.montroysupply.com/catalog/catalogs/SubstratesAluminum/FoamBoards_FluteC411C.pdf

Joe
www.normansinco.com (http://www.normansinco.com)