PDA

View Full Version : Has anyone cut divinycell foam?



knight_toolworks
02-27-2008, 06:55 PM
I may have a decent job doing some airplane sides out of it. a two sided 3d cut but a simple curved shape so it should be fast. a depth of cut total of about 2.25" I was thinking of doing the roughing cut with a 1.75" straight mortise bit and I have a 2" diameter core bit to do the final cut. I wish I could use it alone but it only has about 1.25" length of cut.
anyone have an idea of cut speeds and rpms?

Brady Watson
02-28-2008, 03:23 PM
4 IPS @ 13,000

It is PVC based and much like Sintra or Komatex PVC. Vacuum hold-down is a must if you are going to be cutting 3D into it. Be conservative with your speeds & feeds as it likes to move around on you...

-B

knight_toolworks
02-28-2008, 03:41 PM
this is a two sided cut. it is a slight curved surface about 3/4" thick so end up with a curved shell. I will be cutting two of them out of a 4'x4' 3" thick piece. the finished cut will look like ( with a 3/4" thick wall. the parts are 20" wide so there is some material on each side for hold down when I flip it. but the inside will be hollow so I see only strips on each end and middle to hold it down. I can make a vac board for that but not sure if thats enough hold down.

Brady Watson
02-28-2008, 09:58 PM
Well then...vacuum is out. If you are making more than 2 of these (or you priced it appropriately), it wouldn't be a bad idea to offset the 3D to the inside (making it smaller) and make a 3D vacuum jig that the 2nd side can suck down to. You really have to be conservative when cutting a 2-sided thin-walled part since the tool will either push or pull the skin up or down, causing it to be inconsistent in wall thickness.

-B

knight_toolworks
02-29-2008, 01:35 AM
I was thinking the same thing. if it is cost effective to make these then I was thinking of making the twin humps to hold it in place.
the problem is getting an estimate of the time to cut them. till the 3d file is drawn out it is hard to even get a ballpark figure on time to cut it.
atleast the foam is pretty ridged at /34" thick I had a test piece and it was stiffer then I thought and I just used my cam clamp to hold it in place. I will post the 3d files when done to get some more imput.

joe
02-29-2008, 08:31 AM
The hold down isn't much of an issue by using a couple of spots of "Enerfoam 42" around your the sides of your material. This is a foam adhesive, much like the expanding foam purchased at HomeDepot used as insulation filler. Except the can be used over and over. Ours is still good after a year. We use it all the time on 3D work. A sharp putty knife takes the piece right up. Cleans up easily.

To find it, look under EFIS/STUCCO at Demand Products. This is one of those little secret products which really comes in handy. It's much more effecient than vacuum hold down on 3D carving.
www.demandproducts.com (http://www.demandproducts.com)

I'd suggest purchasing their cheap $25.00 gun. A can of foam glue is about $15.00.

knight_toolworks
02-29-2008, 01:32 PM
great info I will have to get some if this job goes through.

brucehiggins
02-29-2008, 02:14 PM
Joe, Sounds like great stuff. How long do you have to wait after applying before cutting material? You say you can re-use - just stick it down again? I would love the extra insurance that the vacuum holddown doesn't slip.

joe
02-29-2008, 09:05 PM
Bruce,

If you go to the Damand website and look at their adhesives, you will see there are several suggested set up times. I glue up my material on 3/4" plywood about ten minutes in advance. The background's cut a little larger that my piece to be machined. Then the plywood is screwed to the router bed.

Keep in mind this adhsive isn't to be used under your product. You spot it around the sides of your material. Some folks put a full bead on all sides. I use a quarter size spot.

Since this adhesive expands dramatically, it wouldn't work to put it beneath. That's probably my fault not explaining it's use. I'll take a snapshot tomorrow and post it for you.

We scraped all the vacuul stuff three years ago and haven't missed it. Good riddens to the noise and trouble. I like hold down, clamps, screws, and adhesives. "Verks For Me"