Help please: cutting styrofoam sheets

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My shop has a steel roll-up "garage" door that faces a blistering sun for several hrs/day. I'm determined to insulate it. The easiest way I see is to slap some styrofoam shhet insulation onto it.
I can get 4' X 8' sheets at Big-Box for a good-enouhg price, but need to trim the sheets down to ~ 44" X 22" to fit into the recesses of the door.
What's the best way to cut 1-1/2" or 2" styrofoam sheets? I don't have a "hot wire" cutting tool.
Thanks a heap, --Zz
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Buy a hot wire cutting tool... Or rent one if you can...
Any other method of cutting those expanded polystyrene Styrofoam panels will result in thousands of the little polystyrene balls flying everywhere and could result in tear outs near corners and edges...
As for the door itself, is it a standard garage door or one of those commercial ones made up of the skinny segments ?
You can insulate a standard garage door but those steel segmented doors shouldn't have anything attached to them like that, you could build a portable insulated partition and move it in place when you want the door to be insulated...
You might find it easier in the long run to install some sort of awning to shade the door than to mess around trying to block the heat on the inside of the door after it has penetrated...
~~ Evan
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On Sat, 3 Jul 2010 16:20:25 -0700 (PDT), Evan

It's got 4 horizontal segments, it doesn't "roll" up, but slides along runners and lays flat against the ceiling when open.

I thought about that, but it faces the street and neighbourhood, and I'm not sure how that'd be appreciated.

THe styrofoam will only set me back $80 or so, and it'd be WAY easier than building and awning.
Evan, I appreciate your response.
-Zz

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A retractable awning would only cost a few hundred dollars...
You would only extend the awning on days when you wanted to work inside the space to shade it from the hot sun...
~~ Evan
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I've cut many pieces of styrofoam sheets with hardly any mess using one of these knives
http://pipeknife.com/glass/pipeknife.asp
and the second blade down here
http://pipeknife.com/glass/blades.asp
which extends 3" after it is placed in the knife.
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Yup, any of those tools would work well on the extruded polystyrene panels which are blue or pink and fairly solid -- however ANY of those used on white expanded polystyrene would create such a mess you would never want to drink out of a Styrofoam cup or see a box with those white cast corner pieces in it ever again...
You can really only cut foam paneling accurately around any obstacles with a hot wire cutter... I challenge you to cut out a perfectly round hole for a pipe without having to fill the overly large hole you cut out with your utility knife with some other kind of foam sealant out of a can... Using edged tools to cut this material is ok for straight cuts to trim panels to size, but as soon as you need to start fitting it to an odd shape, the hot wire cutter is the only way to go for doing the job right the first time...
~~ Evan
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Any of what tools?
I posted a link with *one* tool, a "pipeknife", and a blade from the same link that would accomplish what the OP wants to do without leaving a "mess".
I've cut plenty of the white styrofoam w/o leaving a "mess" with the tool and blade mentioned above.

A challenge? lol
The OP wants to put some styrofoam on the inside of his garage door.
No need to be perfectly accurate. The tool and blade that I posted would do the job.
You are over-thinking.
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-snip-

If you don't need to pay shipping, a hot knife can be had at Harbor Freight for $20. There are some on ebay for $25 with shipping.
I've used a serrated steak knife with a minimum of mess.
Jim
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wrote:

SEE? THAT's why I post here. And why Usenet is of such value.
Thanks Jim.
-Zz
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On Saturday, July 3, 2010 4:39:16 PM UTC-7, Zz Yzx wrote:

+1 for the serrated knife approach. Thanks! Bob
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In typed:

If it's real insulating styro and not just the junk stuff: I use a fine blade in a jig saw for finer work and a ply blade in my circular saw for the long cuts or arcs. Works well & not a bad mess unless you twist the circular saw so the back of the blade hits the styro. Use the closed dell insulating styro; the junk stuff will disappoint you badly as it's not a good insulator.
HTH,
Twayne`
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Twayne wrote:

Absolutely, you want to use the extruded polystyrene (XPS), not the expanded (bead type) polystyrene (EPS).
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Make one!
When me and a buddy worked at "a place", we were told to make a whole buncha foam dividers, about 2" thick, for a whole buncha containers, about a dozen per container. It woulda taken forever to cut by hand. Days.
Since we had nearly unlimited resources and were too stupid to know any better, we thought, "let's make a hot wire foam band saw thingie". Some 1-1/2" channel stock, some chromium wire, some lamp plug wire, a 110V Variac, and a couple of insulators and we were in business. We bolted the whole thing together in an afternoon and hooked up it up. We cranked up the Variac till the chromium wire began to glow and ran a piece through it. Worked like a charm! We finished that day by mapping out the piece cuts and gathering foam stock. We finished the whole project the next day.
You may be able to rent a Variac. I've seen chromium wire on the web for about $50 roll, but didn't look real hard. I'm sure you can find it cheaper. I'll let you work out the construction details. Our rig was just as crude as it sounds, but worked like a thousand dollar machine. ;)
nb
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On 7/3/2010 6:56 PM, notbob wrote:

You could also get the nichrome wire from an old electric clothes dryer or electric heater. Perhaps a 1,000 watt light dimmer would work as a heat control?
TDD
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wrote:

There's more than one kind of stryfoam maybe. What they had in the 50's was foamed plastic, hence the name. Stiff, with lots of air bubbles.
Then theres the kind with lots of 3mm. beads crushed together. I don't know for sure if that is styrofoam or not.
Maybe there are more.
Others have given good answers. Just wanted to add that for cutting foam rubber, an electric knife is great and what the stores use. There's is designed to have the blade pointing up from the table, for a straighter line, but it works well with a regular knife. But that's foam rubber, not styrofoam.
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There is only one Styrofoam. It is the blue extruded polystyrene foam board sold by Dow under the registered trade name of Styrofoam. Owens Corning sells a similar board (Foamular) colored pink, GP sells a yellow board.
There is also the white material that is actually expanded polystyrene board (EPS) that is molded as a large billet and then cut into slabs by hot wire cutters. It is often referred to wrongly as Styrofoam but the Dow lawyers will correct you on that. The only problem with the white eps board is that suppliers often make it as cheap as possible and do not fuse the bead as well as it should be and you get some loose bead.
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40 TPI hacksaw blade?
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You have to be careful with that. It can ignite the gas.
Wait, wrong thread.
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wrote:

I cut a bunch with my table saw using the fence and it seemed to work great (no split outs), but like you say, it was snowing in Florida for a while. I got a shop vac full of little round foam BBs. It turned out OK, my wife said they were great in her potting soil.
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On Jul 3, 9:49pm, snipped-for-privacy@aol.com wrote:

No matter what you use to cut it, do it outdoors!!!!
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