Cutting plastic

What sort of circular saw blade should be used to cut plexiglas (Lexan) of 1/8 inch thickness? This is to make fixed windows, screwed flat to the structure of a shed.
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Don Phillipson
Carlsbad Springs
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A sharp plywood blade would work. More teeth the better.
Go slow and let the saw do the work especially when finishing a cut.
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On Sun, 10 Jul 2005 09:30:51 -0400, Don Phillipson

Howsa 'bout a plexiglass blade?
All SORTS of tricks exist for this, and ymmv.
If you have a lot of plexi or Lexan (they aren't quite the same material) to cut, consider a dedicated blade designed for the purpose.
Failing that, try the material manufacturers' websites for any relevant application notes. In general manufacturers want you to feel warm and fuzzy about using their stuff, so they try to make sound recommendations.
Some woodworkers swear by reversing an 80-tooth sawblade (so it turns the wrong way).
I've done short runs, say five or six cuts, using an matt knife and a straight edge. After several scores, it snaps right off cleanly.
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Charles Krug wrote:

These work better: http://www.tapplastics.com/shop/product.php?pid 
R
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I have used those on plastic they are great and I just used one to cut 1/4" backer board worked great to scribe it but did have to keep sharpening it.
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wrote:

Yeah, a knife or box cutter can work too. I've done it.
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Lexan is a trade name for polycarbonate plastic. Plexiglas is a trade name for acrylic plastic. Which do you have?
Assuming acrylic: The best blade is a triple chip, alternating profile tooth with 80 carbide teeth on a 10" blade. Rake should not exceed 5 Deg. These are typically a special order item and cost around $100 or more.
Getting a Terry-Fletcher plastic scoring tool is better for smaller projects. They cost around $6 and last long. Avoid those cheap plastic cutters with the swing open blade. You can avoid any cutting work by asking a hardware store or a picture framing business to cut it for you. They likely have a machine to cut it for you.
I don't recommend screwing it to the window frame. plastic expands and contracts with varying temperatures so it needs room to move. It is much better to mount it in a channel system allowing 1/32" per foot for expansion. Also, screws cause high stress points that detracts from the material's high impact strength. John
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JohnR66 wrote:

Building a shed. $100 blade for a couple or three windows? Cost more than the windows probably.

I wasn't recommending a particular brand or style of cutter, just pointing out the difference between a dedicated plastic scoring tool as opposed to cutting it with a utility knife. I'll remember the Terry-Fletcher brand name for future reference. Thanks.

In other words, it will probably crack at those screw holes. Thanks for clarifying, John.
R
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Try using a router to cut it works for me
wrote:

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My son used my Roto-zip to cut plexiglass. It worked real good.
Dean Swinger wrote:

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On Sun, 10 Jul 2005 09:30:51 -0400, someone wrote:

Like the other guy said, Lexan is a very different thing from plexiglas. Lexan is a very high strength engineered plastic and not typically used on DIY projects or stocked in local hardware stores. If you have Lexan, you probably made a special effort to get it.
I used to have an office in Pittsfield, MA which considered itself the home of Lexan (GE Plastics) and has a road named Dan Fox Drive; I have been told that Dan Fox was the inventor but have not tried to verify that.
Reply to NG only - this e.mail address goes to a kill file.
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v wrote:

Home Depot stocks it around here.
R
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From the Company files, http://www.gelexan.com/gelexan/fox_bio.html
Bill
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Normally with a delicate plastic you can flip the blade around. (getting the right blade is the best choice, but there are others)
This makes it sort of grind rather than cut. I did the siding on my house this way, worked real well.
Tom
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On Sun, 10 Jul 2005 09:30:51 -0400, "Don Phillipson"

I use a thin kerf 7.25 inch carbide tipped blade to good effect. The blade is half the thickness of a regular blade and used for cutting thin panels. Cheap too - Under $10 a blade if I recall.
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If your material is 1/8", then you need a blade with at least 16 teeth per inch. Personally, I use a saber-saw with a hacksaw blade, and go really slowly. If you need a clean edge, sandwich the cut with scrap wood.
At my local borg store, you can get four different kinds of clear plastic, ranging from lucite to lexan, with price about proportional to strength.
Crystal-lite (with the pink backing) is far less likely to chip, crack, or spall during cutting than the lucite, so I only use lucite where I can bury the edges in putty. Lexan probably won't chip at all.
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