Any Tips For Cutting Plexi?

[MBL]

Howdy all, Tim here. I was wondering if there are any tried and true methods for cutting plexiglass. I need to have some curved sides and don't know if scoring and breaking is the way to go...or if I should use a saw. Any ideas? Any help on this would be great!
Thanks
Tim
MBL

[Antibilly]

If you cut plexi use a jig saw and do it when its cool or in the AC. if not the cut plexi will melt onto your glass and make a mess

[gears-n-grease]

A jig saw with adjustable speed and a medium fine tooth blade work good. I have found that if you use to high of a speed it kinda molds the shavings back in ,in some places.I have only found the snaping method good for straight stuff and it works better if you clamp half the plexi to something straight along the edge while snapping it.

[KCsledz]

I would also add use masking tape and tape off where you are going to cut then draw your guide line. It won't help the physical attributes of the cutting process but you can see where to guide the saw a bit easier.

[old beet]

Spend the xtra $ for Lexan. Won't run or crack........OLDBEET

[bigron]

[ QUOTE ]
Spend the xtra $ for Lexan. Won't run or crack........OLDBEET

[/ QUOTE ]

definetly go with the lexan. you can cut it on a foot shear. way easier to work with.

[MBL]

Thanks for the tips! Now this Lexan...can I get this at the Home Depot? Lowes?
Tim
MBL

[Ron]

They have reg Lexan and scratch resistant Lexan. If you know anybody that builds circle track cars most of time they know were to get the best deals on it.

These saws do a real nice job
Rotozip (http://www.sears.com/sr/javasr/product.do?BV_SessionID=@@@@1455587949.1096290329@ @@@&BV_EngineID=cchhadcmilddgdecehgcemgdffmdggg.0& vertical=TOOL&pid=00926559000)

I have used them on Lexan then took a sanding block or sandpaper to the edges.

[bigron]

i've seen it at lowes but i'd call around you can probrably buy a whole sheet for what lowes wants for a small piece. don't know how thick your wanting but you can also use tinsnips to cut as long as it's not to thick. they may even cut it for you where you buy it.

[C9]

Lexan, a trade name is also known as Polycarbonate and Polycarbonate is what you'll find at Home Depot and the like.

It comes with a protective paper glued on - as does plexi.
Leave the paper on until you install the Lexan.

I cut Lexan on a 10" table saw equipped with a 60 tooth carbide blade.
It cuts easy and leaves a pretty good finish.
Do be careful to hold the Lexan down and don't let it raise up due to the action of the saw and when it flaps back down many times a small chunk is broken off the edge. The Lexan wants to raise when the back side of the circular saw blade is coming up through the kerf.
Depending on the thickness of the Lexan it may not be a problem, but it is something to look out for when cutting 1/8" or 3/16".

When cutting curves I take off what I can with the table saw and bring the curved area into complicance with a disc sander on a table.

I've also had success cutting Plexiglas with a router, but you have to be careful to run the cut in the proper direction.
One way the router cuts fine, the other tends to pull the cutting bit into the Plexi.
Similar to a "climb" or "non-climb" cut on a mill.

If you use a router do the cut with a straight sided plain (non-ball bearing) cutting bit about 1/8 - 3/16" in diameter.
Clamp a straight edge on the Plexi as a guide.

These techniques for cutting Plexi should work for Lexan as well.

Be aware that cutting with a router builds up a pretty good static charge and if you're cutting a big piece you'll have the static electricity go to ground through your shoes.
Especially if you're doing the cut on a floor that has metal plates. (As the power station I worked at did.)

Note that many Polycarbonates have a solar resistant coating on one side. That side goes toward the sun.

Clean it with soap and water, rinse well and dry with a very soft cloth.
It will remain unscratched and optically clear for a long time with reasonable care.

[MBL]

I am looking to use about a 3/16th thickness...I don't have the big equipment though....I might just try it with a hand held jigsaw....we'll see. Now I plan on using this as a temporary windshield....I know not the best idea...what thoughts are there on this? I know some on the HAMB have a plexi windshield.
Tim
MBL

[C9]

Use a fine tooth blade.

Check the shoe on the Sabre saw/Jigsaw and make sure there are no sharp corners.
If so, file em smooth or round.
If you don't get rid of the sharp corners, protective paper or not you'll scratch the Lexan/Plexi.

Fwiw - my little brother uses 1/8" Lexan in his drag race Henry J (166mph @ 8.13) and the windshield is hanging in there ok.
It's a one piece windshield with the V-Butt area heated and bent to shape instead of the two-piece flat pane windshield the stock HJ's use.
The windshield is well supported in the stock windshield well and has quite a few pop rivets retaining it.
The many rivets bit are what make it work so well.

The windshield has bowed in a bit, but it doesn't look to be a problem.
Even so, if it were my car I'd take the weight penalty and use 3/16"

Fwiw #2 - Lexan is what is used in the aircraft industry for windshields.
Granted, they're curved and self-support themselves well, but they have a proven track record with many years of use behind them.
Jet fighters and the like use Lexan for canopies as well.

A temporary Lexan windshield should be just that. Temporary.
Using wipers on it will scratch it up in no time.

[Slag Kustom]

i used 3/16 lexan in one of my race cars with no problems.

how are you installing it (ruber gasget or glueing it with urethane) ???

[Rand Man]

You can use a jigsaw for your project if you follow a few of the rules suggested here. I would cut a pattern out of something fairly solid like 3/4" plywood. Clamp your "glass" to the board to keep it from flopping. You might want to sandwich the glass between two pieces. Score the cut line with a new, sharp utility blade. Buy a good jigsaw blade designed for the job.

[MBL]

It is going on my 26 Model T Roadster. I made a windshield frame out of 5/8ths copper tubing. I shaped the bottom to match the cowl and the sides to match the stanchions. Then I cut a slit to fit the glass/plexy..I will probably use some sort of rubbery tape to dress the edge that goes against the glass.
Tim
MBL

[48_HEMI]

you really need to engineer a fastening system on a windshield. all plastics are flexible and bow in the wind. they can slip out of the groove at speed. race cars screw them in. ureathane will probably work after a proper cure (7-14 days) Copper tubing and lexan are both soft make damn sure that screw the copper to the cowl before you put the lexan in. http://www.jalopyjournal.com/ubbthreads/images/graemlins/smile.gif

[bigron]

i would not use plexiglass for a windshield. plexiglass can shatter. 3/16" you should be able to cut with some tin snips.

[MBL]

How do people hold the glass/plexi in when they use only the groove in the stanchions?
Tim
MBL

[4t64rd]

There's a place on U.S. 19 over here, Farco Plastics, they have everything, and will cut it if you pay them. If not, 32T blade in your jigsaw, slow speed. leave the paper on, if you want to get fancy and make sure you don't get stress cracks later, you can "flame polish" the edges with a propane torch, makes them shiny and smooth, leaves no area for cracks to start. I used to design retail product displays out of plexi and lexan, so I'm not fucking with you.

If you go to the Thomas Register website and search for boat windshields and look for one around here, they might be able to give you more advice.

One more thing, if you redesign your windshield to have a slight curve, either direction, you might get enough structure in it to overcome the bowing at speed.

[safariknut]

I would only add to what has already been said:Use Lexan for it's shatter resistance.To cut it,I've used a jigsaw(slightly modified)with a fine tooth blade and used duct tape on the"shoes"of the saw(the metal pieces on either side of the blade)to keep it from scratching the surface.Feeding it really slow and having both sides clamped firmly to keep from shattering the edges.The flame polishing idea sounds like a definite plan and I never knew about the UV coating on one side;thanks for the info.

[MBL]

I don't plan on using it as a permanent fix but rather a temp placement and template for the actual glass. I am hearing mixed ideas about using it though...some say don't ever and some say fine in a race car....glass will shatter too...what is it about he plexi should I be worried about?
Tim
MBL

[Sinner]

Plexi will shatter, lexan won't. That's what everyone is saying.
I would use the lexan, it costs more but it won't shatter into long sharp pieces.

[Rand Man]

Have you been down to the local glass shop and priced a piece of flat safety glass? One trick used to be cut down an early Ford Bronco windshield down.

[fastcat]

You can get Lexan sheets on ebay from a couple companies. They sell the pieces they have left over from jobs at a good discount. Look for the lexan with a coating called MR10 it is a scratch resistant coating. I picked up lexan for all the doors and winshield for my project. Shawn

[james]

Okay, I thought this was common knowledge, but maybe not. The best way to cut plastic (plexi or lexan) is jigsaw with fine, fine blade, but first go to home depot and buy some peices of styrofoam. The cheap white stuff they make those $1 coolers out of. Make sure it's as thick as the length of you jigsaw blade.Set your lexan on the foam and go at it. That's the big secret. The foam gives 100% support, yet the jigsaw slices throgh it like butter. I've cut fairly intricate channel letters like this and rarely have a crack. Another secret is - if you need to drill holes, set your drill on reverse. It takes a little longer, but same thing-- won't chip or crack.

[noboD]

MBL, to make yourself feel better about the Lexan not breaking, take a piece of scrap and lay it on the floor and hit it with a hammer. Really tough stuff. I had a piece of 1 inch thick Lexan and shot it with my 45 cal.1911, wouldn't go through. You can also bend it in a sheetmetal brake if you need, give it plenty of clearance.