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CNC'ing foamboard

Monolith

I was wondering if anybody is aware of this being done before? As my last job was as a CNC programmer, I'm interested in sticking a load of foam boards on top of one another to form a big cube. I'd then like to CNC the block into a model.

Any opinions or ideas? And indeed does anyone have any relevant links to building architectural models via the CNC process?

Thanks.

 
Mar 8, 07 12:21 pm
won and done williams

In school, we'd laminate sheets of plywood and CNC route them. Not sure how this would be done with foamboard. You'd have to be sure they don't delaminate while routing. There are of course limitations in depth, etc. based on your various drill bits.

What tools were you using when you were a CNC programmer? I imagine you'd have more experience with this than I would.

Mar 8, 07 12:52 pm  · 
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mdler

I dont know if the heat would catch the foam on fire or not?

Mar 8, 07 1:03 pm  · 
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postal

i'm not sure about foamboard...but I've done it with blue rigid insulation foam...

you may need to test it out a few time to make sure it works...

getting a good lamination would be key...

along with trying different bits and speeds in order to make sure you're cutting through the foam board, not ripping or melting...

wait, what kind of CNC machine are you using? 3-axis? 5-axis? Water jet? Plasma!

Mar 8, 07 1:34 pm  · 
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strlt_typ

a studiomate and i have once cnc'd layers of foam for a project. in school it was a common material to use (instead of wood) for building models/forms because it doesn't put too much wear on the bits.

we used the hardest/stiffest foam we could find (can't remember the rating system used but you can easily find this out). this will give you less crumbling on the surface but this is no big deal since you can sand the model afterwards...the foam we used, from what i remember, was about 1"-1.5" thick...

we used elmer's ultimate glue and didn't get any de-lamination...make sure you cover every surface and some of the glue will fill the crevasses on the foam's surface so apply about a 1/16" of an inch thick layer of glue...


use plywood to sandwich the layers together and clamp...

our foam model was eventually used as a mold for vacuum forming...

Mar 8, 07 1:43 pm  · 
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strlt_typ

to clarify, like what postal used, we used rigid insulation foam...

Mar 8, 07 1:47 pm  · 
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postal
Class Documentation

Here's some documentation of our little CNC projects... We analyzed our parts using Dr. Frames, Autodesk Inventor, then used Rhino w/ MADCAM to send to "The Boss" (3-axis) (Thank you SOM for your kind donation, ha), used foam molds to make sand molds, and sand molds to cast parts in aluminum.

I wish I had some pictures of the 5-axis monster machine that they had just got. (Thank you Felsen's Grant Money)

Mar 8, 07 1:59 pm  · 
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mdler

mmm..poly glue. 1st time I used that stuff, washed my hand with water afterwards. Wasnt aware that the glue is water activated

Mar 8, 07 2:04 pm  · 
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PerCorell

Eh my only experience are with a piano wire glow cutter or what it is called ; with that you can draw out lines ,then what lines would you need to transfere from scale printed sections other than 3D-H. If anything is easy it is to print full scale and transfere that to the sheet, then cut it by hand by following the lines allowing the piano wire , acturly a specialised tool that highen the woltage as soon as the temperture of the wire lower.

Mar 8, 07 2:43 pm  · 
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binary

you can get precision board in various densities ...comes in a beige and a pink color

Mar 8, 07 3:52 pm  · 
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Monolith

Thanks so much for all of your replies.

When I was a CNC programmer, I was CNCing emboss, cutter and foil dies in brass and magnesium.

As mdlr mentions, there may well be a fire risk. I'm not sure of the exact tech spec of the Heidenhain & Cincinnati machines we had but I know the drill revolution speed was fairly low, as a high setting often resulted in the fine drill bits snapping on precision cuts.

I'll ask my ex-workmate for his opinion. Perhaps I could model out of a lump of magnesium!?

Thanks again.

Mar 8, 07 5:13 pm  · 
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flashpan

We've done it. No problem with heat, just set the spindle speed low (5000rpm), use a straight-flute bit, and set the feed low as well (50 inch/min.)

However, if your foam board has a paper backer, you will have problems getting a clean cut. Paper doesn't like to be routed, but it does like to be cut. You will get a sort of torn edge no matter what settings you specify.

If you could find a rotating signcutter's blade for your router, that would likely produce the best results with any product that is paper-like.

Good luck

Mar 8, 07 5:30 pm  · 
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Monolith

Thanks flashpan. Would be good to speak to you further if thats cool? I don;t know how the IM system works here? Do you have an email address or can I give you mine?

Glad to hear this can be done, as I think with the non paper laminate foam boards, a model of what I have in mind would look great.

Mar 8, 07 5:39 pm  · 
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EdgewoodAnimal

We've used it in our office. It cuts like butter. Really clean models - especially for topos. Our foam came in 3" thick by about 3'x7' sheets.

Mar 9, 07 1:14 pm  · 
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