Cutting Foam

[ron]

Robert,

I have a little router/foam experience. Most of my 'foam work' was helping with some faux rock work, plaster overlay over styrofoam. There is where I found rotary files were not the tool, IMHO.

On a ShopBot I would try standard carbide bits, slow down the RPMs and up the Move speeds. Boy are you going to create a lot of 'foam mess'.

[seaside@esva.net]

Robert,

I haven't cut foam myself, but others have said that dust collection is especially important, particularly if you have a ball-screw z-axis. Seems the foam dust gets into the nut for the ball screw and binds up all the little ball bearings.

Bill

[robin]

I have cut quite a bit of foam on several occasions (before I had the ball screw) and found after a time the machine started to slip and stall. Several hours of head scratching later I discovered a build-up of foam dust (it becomes "gummy") on the cable pulleys. After a careful cleaning the problem disappeared.

I don't doubt the same could happen to the recipricating bearings in the ball screw setup with a much more difficult cleaning required.

[birdsofplay]

You are very correct sir !

I've run into the same problems making a large
LOGO sign for my Building. With raised letters
I had to take off a lot of foam. It took several hours to complete the job.

Lots of PINK schmeez all over the place.

I just wait for a windy day, open all the doors and windows and run up the compressor ... wheee !

[rickb]

Robert,
re: cutting styrofoam
Check out the "Percival" cutters from King Arthur's Tools. NOT a router bit but a cutter designed for a die grinder. About 2" in diameter on an extended ball bearing handled shaft. The cutters are saw chain (chain saw stuff) in a small endless loop, clamped between a pair of spring steel disks attached to a mandrel. Larger sizes named "Launcelot" and "Squire" mount in a 4.5 to 5" angle grinder. They are popular with people who build log cabins, carve totem poles and do ice sculptures. They can really hog out material fast and rough or can be used with finess for a relatively fine finish. Because of the extended shaft length of the Percival, a die grinder mounted in a "bot" could use a good portion of the possible z axis. At the last National Hardware Show I asked the tool's developer about using the Percival in a router and he tended to not recommend it as it had not been designed for that use and so not tested.
More info at katools.com
You should be able to bury your shopbot in foam dust in a few minutes using this, maybe even do slight undercuts with it.
Hope all this helped.

[birdsofplay]

That might keen for 3D foam sculpting.

For lettering it's kinda course IMHO :-)
unless your doing really BIG letters.

I suppose you can choose yer poison
either take off more depth but a narrower
cut using a long spiral router bit OR
take off a lot of width but only limited depth
( i expect the Percival to be about 1/4 to 3/8" )
Plus, as you say, it's probably NOT a good idea to
run it up to 10K rpm on a big PC 3.25HP.

Either way, larger signs are usually "one timers"
so they are worth the wait, however they are produced.

Thanks for the tip

[shimp@bellsouth.net]

I have had my "bot" for about a month. Can someone tell me how to hog out material going from signlab 6 to the file conversion then file part command? ie. leave raised copy/border.thanks

[danhamm@abccom.bc.ca]

Roy,
From Signlab export your file as a DXF.line file.
In the shopbot program use file conversion to convert your DXF.file to shopbot file..

You can use colors for different depths of your cuts, and you can export your file in pieces to account for bit changes edge profiles and or flat
bottom for hogging backgrounds and roundovers for
lettering..
You can edit your sbp.files in notepad or word or
any text editor..as to put more than one file together and put in pauses for bit changes..
I hope this helps..

[Mayo]

Signlab has a shopbot driver (available on the shopbot web site under downloads) which will write .sbp files - no conversion is necessary. It doesn't mention if it will work on ver. 6 SignLab though - it mentions ver. 5 and earlier. Install it the same as installing a plotter driver. Cut to file using the shopbot driver and it generates an .sbp file.