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How to cut lexan/plexiglass?

Started by dleary, Jan 27, 2016, 05:46 am

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dleary

Hi,

I'm new to the board, so please forgive my ignorance on many of the questions I am likely to post in the coming months.  I live in central North Carolina (USA) and generally my go-to hardware store is Lowes or Home Depot.

This is my first ever post and it concerns windows.  I will be using thick lexan/plexiglass (around 5 - 6 mm thick) for my TARDIS build.  I want lexan because putting the police box together and taking it apart requires some banging of rubber mallets, and I'm afraid that glass would break.  I want thicker lexan because I want to give the police box the appearance of having real, sturdy glass (no give to the touch or when pressed on.  Anyhow, I was wondering how lexan is best cut to size.  Is there a power tool and method to get it done neatly and effortlessly?  I can't imagine using one of those manual "scoring" knives to cut through a thick piece of lexan.  I would be hating it.

Home Depot sells large, thick lexan sheets, but they do *not* cut them to your desired sizes.  Lowes also sells them, and *may* cut them to size because they have them right next to what appears to be an "industrial strength scoring device" that is not electric, but it accommodates larger-sized pieces of lexan.  I would prefer, however, to cut it myself with a power tool, rather than relying upon an under-motivated, under-paid and probably annoyed employee cutting it for me.  I'd probably start out with a bribe of $20. for his trouble.

SO - does anyone have any advice for me?  Thanks in advance!
Nos e Te Ipsum.

Volpone

5-6mm is a lot thicker than I've tried this with, but I put in tile in my bathroom.  (Be patient, I'll get there.)  Nowadays, instead of tiling drywall, they make something called Hardiboard, which is like drywall, but with concrete instead of gypsum.  Much sturdier and less susceptible to mold.  You score Hardiboard the way you would drywall (or you can cut it with a circle saw, goggles, and a mask, and then throw away the saw blade), only instead of a utility knife, you buy a special diamond tipped cutter. 

I've put down a plywood cutting surface and with a steel straight edge, some patience, and a number of passes, I've made some very nice clean cuts in plexi half as thick as what you're working on. 

If you try it, let me know how it works for you.  http://www.pureadhesion.co.uk/images/detailed/Hardie-Backer-Carbide-Tipped-Cutting-Knife.jpg
"My dear Litefoot, I've got a lantern and a pair of waders, and possibly the most fearsome piece of hand artillery in all England. What could possibly go wrong?"
-The Doctor.

Elvis Gump

Also another method I have found as long as all you want is a cut edge, and if you have a standard 10" table saw, you can use the 180 tooth veneer saw blade. I leave on the protective film, but take care to attach a nice smooth board against your fence to prevent thin plexi from catching if the fence has a rounded edge where the fence meets the table that the plexi might be able to slide under and the snag, thus ruining your cut. This method will sometimes make the plexi cut edge melt, especially causing the chips to fuse a little, but you'll see that is easily brushed away and your edge will be fine. A good shop vac will help with the clean up.
Lowe's will cut it for you to size; the cutter is really just a scoring machine, which the scored edge is the snapped in. Same basically with glass, you don't really cut glass, you score and break it.
Thicker stuff like the Lexan requires a lot of scoring cut and you go through lots of blades that way so if you're cutting and the edge will be tucked into a frame, the table saw is quicker.

Elvis Gump

Quote from: volpone on Jan 27, 2016, 06:00 am
5-6mm is a lot thicker than I've tried this with, but I put in tile in my bathroom.  (Be patient, I'll get there.)  Nowadays, instead of tiling drywall, they make something called Hardiboard, which is like drywall, but with concrete instead of gypsum.  Much sturdier and less susceptible to mold.  You score Hardiboard the way you would drywall (or you can cut it with a circle saw, goggles, and a mask, and then throw away the saw blade), only instead of a utility knife, you buy a special diamond tipped cutter. 

I've put down a plywood cutting surface and with a steel straight edge, some patience, and a number of passes, I've made some very nice clean cuts in plexi half as thick as what you're working on. 

If you try it, let me know how it works for you.  http://www.pureadhesion.co.uk/images/detailed/Hardie-Backer-Carbide-Tipped-Cutting-Knife.jpg


For Hardiboard, check Lowes as they sell a special blade with only six carbide teeth on it that is labeled to cut cement board. I've had good luck with mine cutting the siding board and backer board.
http://www.lowes.com/pd_9354-281-4935201___?productId=3240436&pl=1&Ntt=cement+saw+blade

Also I have the little $49.98 saw blade sharpener from Harbor Freight, normally a crappy place for power tools, but being able to resharpen the carbides on wood blades many times with its diamond wheel saves you a lot of money in the long run. So far mine has been great. Don't throw those blades away! Resharpen them on rainy days.
http://www.harborfreight.com/120-volt-circular-saw-blade-sharpener-96687.html

kiwidoc

I've successfully used my tablesaw, jigsaw and bandsaw to cut this up to those thicknesses and been successful each time.   The trick is to take your time and if you have it, leave protective coatings on until afterwards.  good luck!

jorwick

Quote from: kiwidoc on Jan 27, 2016, 08:49 am
I've successfully used my tablesaw, jigsaw and bandsaw to cut this up to those thicknesses and been successful each time.   The trick is to take your time and if you have it, leave protective coatings on until afterwards.  good luck!


I second this.. Having a veneer blade ( or a plastic blade- yes they make blades specifically for cutting plexi and lexan) is MUCH BETTER. But the trick is to go very slowly and ingore that unpleasant plastic burning smell. If you try to go to fast you will crack it and ruin both your cut and potentially your entire stock sheet  

galacticprobe

Jan 28, 2016, 07:27 pm #6 Last Edit: Jan 28, 2016, 07:49 pm by galacticprobe
Welcome to the TARDIS Builders Family, dleary! (I'm not all that far from you - Virginia Beach!)

Anyway, I have to agree with kiwidoc and jorwick. It's been decades since I've cut any plexi (large cuts, anyway... more than an inch or two long). In fact it was in high school so we're talking four decades now - good GLob, how time flies! But when we made several things in Shop Class that needed plexi, we always used the bandsaw or table saw with fine tooth blades. The cuts always came out smooth and didn't take much sanding to get a polished look to the edge.

AH! Wait! I just remembered! (Stupid brain.) I did make a large cut with some .25-inch plexi sooner ago than that: back in 1999 as part of our Coast Guard Chief Petty Officer Initiation. We were required to make a hat box to show off our new CPO hats. My box was huge compared to the others (2-foot square and 18 inches tall - it was designed around a Coast Guard blue pillow so the hat would sit on it like the Crown Jewels). Anyway, the lid of the box was just a frame with a plexiglass panel in it to make the cover. I cut that piece of plexi on the table saw at the Carpenter Shop - four passes on each side to make sure the thing was perfectly square. All it took after that was a few passes across the stationary belt sander to clean up the edges and have the plexi drop right into the frame to make the box's lid.

And as others mentioned, I did leave the protective covering on the plexi until everything was cut and sanded. So the saws mentioned will work just fine and give you nice edges with the blades recommended.

Now about those questions you warned us about - the ones that would be posted "in the coming months"... Never be afraid to ask us anything, no matter how trivial you think the question might be. Someone will always have an answer for you, or know where to fine it. (And the one thing to avoid is starting out with "I know this is a stupid question, but..." Remember: there are no stupid questions, or as my uncle used to say... roughly... 'The only stupid question is the one that doesn't get asked because it never gets answered'.) So ask any question you feel the need to. We're all here to help. ("Remember, I'm pulling for you; we're all in this together." -Red Green)

When you get a chance, if you haven't found it already, check out this post: http://tardisbuilders.com/index.php?topic=6011.0. There is a link in there for the TARDIS Builders Workshop Manual - a free PDF download that was created by one of our members. (More on the Manual in the Helpful Hints post.) There is also a link to some great plans (another free PDF download created by another member) with both imperial and metric measurements for the New Series TARDIS. You can also find plans for some Classic Series versions in our http://tardisbuilders.com/index.php?board=77.0 Section.

So have a browse, prepare for sensory overload, and remember most of all, WE LOVE PHOTOS! So please post loads of photos in your Build Diary so we can watch your Old Girl grow. And then post loads more in the http://tardisbuilders.com/index.php?board=14.0 (this is where the "beauty shots" go) so we can all drool over the lovely lady once she's done.

Once again, welcome to the Family, and good luck with your build!

Dino.
"What's wrong with being childish?! I like being childish." -3rd Doctor, "Terror of the Autons"

warmcanofcoke

At your local hardware store you can buy Blades that cut plastic for your circular saw / table saw. They are the same ones you cut plywood with. If you are looking for a polished edge you can run the edge of the acrylic with a table router, and then if you want the edge to be transparent you will need to run a MAP Gas torch over the edge. (Has to be a MAP Gas Torch - Acetylene just wont cut it - if you forgive the pun.) There are tutorials on youtube. (*Disclaimer: Please seek permission from your parent, significant other or White Guardian before use of power tools and torches. Always use proper safety equipment.)
Nate<br /><br /><br />"The Caves of Androzani": <br />Peri - "I thought you knew everything."<br />The Doctor - "Ahhh, not quite; it's going to worry me until I find out what it is."