Replies

1. 
   Scott | Oct 07, 2009 09:24pm | #1

   I've never been able to find anything better than a brand new large Olfa knife. You're right, there's no way around making a nasty mess, especially with thick board.

   76 sheets is a good score. You'll be a pro at cutting it after all that....

   Scott.

   
   

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   Edited 10/7/2009 2:25 pm by Scott

2. 
   frenchy | Oct 07, 2009 09:26pm | #2

   Take a really sharp utility knife and cuttting at the correct angle cut as deep as you can. then make a matching cut on the opposite side and snap it apart.

    But I'm lazy and want it done fast so I cut it on my table saw a tiny fraction larger then the bay and then stuff it in.. 99% of the time the only spray fill I use is as back up.

3. 
   Piffin | Oct 07, 2009 10:16pm | #3

   I use my tablesaw, but it makes bead dust.

    

    

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1. 
   frenchy | Oct 07, 2009 11:33pm | #6

   Yeh! I should have mentioned the need for a mask on the table saw. Thanks for catching that for me..

1. 
   Piffin | Oct 08, 2009 12:41am | #12

   My table saw does not like to wear a mask 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

1. 
   frenchy | Oct 08, 2009 01:13am | #14

   Hey! where's the little smiley face? 

    That was pretty funny..

    I've got a dust collector I use on mine but still if you don't want to get those beads up your nose or eat them  you'd better put a dust mask on your face.. (please don't ask How I know) 

1. 
   Piffin | Oct 08, 2009 01:38am | #17

   They don't bother me in the least. I was just adressing his Q of wanting something that does not make the dust 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

4. 
   renosteinke | Oct 07, 2009 10:48pm | #4

   That's enough material, and enough special cuts, to make looking into the special Bosch 'foam cutter' worthwhile.

   The tool looks something like a saber saw; the difference is that it has two blades that move in opposite directions. See it here:

   http://www.boschtools.com/Products/Tools/Pages/BoschProductDetail.aspx?pid=1575A

   To be fair, they do say "Foam Rubber Cutter." I'd take a piece of foam to the local fabric / upholstery shop, and see if their tool works on styrofoam.

   Otherwise, look at these:

   http://www.hotwiredirect.com/products/hot-knife/

   
   

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   Edited 10/7/2009 3:50 pm ET by renosteinke

1. 
   CLupis | Oct 08, 2009 12:25am | #11

   The hot wire product looks like a versatile tool.  I've ordered it and will tell you how it works cutting both the expanded polystyrene, and the isocyanoacrylate insulation I'm working with.  Thanks for the lead.

1. 
   JRousseau | Oct 08, 2009 01:31am | #16

   A hot wire tool is going to work with your expanded polystyrene (EPS) or extruded polystyrene (XPS) foam fine. I am doing a similar insulation project and I had a friend cut the EPS to size with his CNC hotwire cutter and used both the hot knife for some detail work and a hand saw when it was handy for getting each piece to fit perfectly. Most hot wire cutters run about 1 inch or so per second so the longer the wire and shorter the distance of travel through the foam the quicker the job will be. (The CNC just chewed through it!)While EPS can burn cleaner than wood at high temps, and does have some fumes at lower temps (ventilation is required), the fumes from the polyiso foam are really bad! DO NOT use a hot wire cutter Polyisocyanurate foam!!!Use a utility knife and a straight edge to get that stuff cut. Also, are you having to cover this with 1/2" drywall for fire safety? That's what I had to do in my location to comply with code. Note: the R-value of the EPS is about 4 per inch and for the Polyiso is about 6.5. They say it's a bit higher when there's an air cavity next to the foil face. So I'm sure this will definitely help keep you comfy in the house.

   Edited 10/7/2009 6:38 pm ET by JRousseau

5. 
   Norman | Oct 07, 2009 11:30pm | #5

   An ancient Skil jigsaw seems to work very well for me.

6. 
   FastEddie | Oct 07, 2009 11:39pm | #7

   Hot wire cutter.

   "Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

1. 
   frenchy | Oct 07, 2009 11:44pm | #9

   I've used them (I have them) and they are nasty!

     Go too slow and the foam  can burst into flame, go too fast and the cutter get's stuck. start too soon and it takes longer to heat up.   Either way they are stinky and much slower than a table saw or a simple score and snap..  

7. 
   TJK | Oct 07, 2009 11:41pm | #8

   You could make a hot-wire cutter without too much trouble. It will make some noxious fumes, but the cuts will be clean and mess free. Here's an example:

   http://www.instructables.com/id/Hot-wire-foam-cutter/

   and there are probably hundreds more on the web.

8. 
   RedfordHenry | Oct 08, 2009 12:18am | #10

   Tajima box cutter (the large one with the big blade) is the best tool I have found for extruded and polyiso foam.  Have never used it for expanded though.

9. 
   SamT | Oct 08, 2009 01:09am | #13

   22 TPI hacksaw blade used as a pull saw.

   SamT
   A Pragmatic Classical Liberal, aka Libertarian.

   I'm always right!
   Except when I'm not.

10. 
    [email protected] | Oct 08, 2009 01:21am | #15

    Hot wire would be the first choice.  Followed by, a power carving knife with the two blades that slide past each other. 

    If you use the carving knife, a bit of slightly soapy, (3-drops of dish soap per quart) water in a spray bottle makes a good lubricant.  Waxing the blades with a bit of paraffin also helps.