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  1. #1

    Plexiglass cutting

    I need to cut from 1/8 to 1/4inch plexiglass for my bridge windows. There is a curve to the windows so no straight line. I have the origional windows removed so there is a templet. ANYONE have a surefire way to cut plexiglass easily without cracking or splintering the edges?
    thanks
    Rian

  2. #2

    Re: Plexiglass cutting

    Use a sabre saw with a fine tooth blade. Not a a real fine metal cut.ting blade, but a relatively fine wood cutting type. Rub it with a wax candle and continue to do that while cutting. Use a slow speed and keep the preassure on. Don't let it get hot and melt the plastic. If yo have a tight turn, switch to a blade that is narrow front to back. You can block sand the edge smooth after cutting to eliminate any stress cracks.

  3. #3

    Re: Plexiglass cutting

    I can help you with this, being my old line of work, all we did was cut plexiglass all day. You can do it by hand, and is really the safest way.

    Put your old window on the new sheet and trace it out. And then get a plexiglass cutting tool ( you can get one of these at Lowes or Home Depot ) and with the first cut, slowly score just inside of your line the first time, and then do it again, and as you get deeper with your cut, you can increase the speed and the pressure on your plexi. If you are using 1/4 inch, this can be done in about 5 or six passes. Then Bring you scored line to the edge of the table, and start at one end, and just start snapping it all the way across, Then to preety up your edge, use a propane torch in the rough edge, not to close, and just heat it till it is smooth, just keep the heat moving.

    The glass you buy comes 4x8 sheets or you can buy a half sheet. Just utilize the piece you buy, and if you have to draw it out a couple times, ( might just mess the first one up ) then you can try it again.

    Or you can just take it to a glass/ plexiglass store which specializes in car's , bathrooms etc etc, and take them the piece off the boat, and have them do it for you.

    Good Luck

    Dan

  4. #4

    Re: Plexiglass cutting

    Dan .... what is the best way to bend .080 plexi? The supplier told me that it takes 280 degrees of heat to make the plexi bendable. Thanks.

  5. #5

    Re: Plexiglass cutting

    EZ,

    This is what we used to make 90 degree bends

    http://www.professionalplastics.com/...ending-acrylic

    and for other kinds of bend, we used a heat gun. Just make sure you keep constant heat and distribute it evenly along the place you want to bend!!

    I have hear of a household oven being used, like for making the bends in a Venturey windshield on a boat, coarse it can't be too big, unless you use a pizza oven at Domino's or something....LOL.

    What are you wanting to bend???

    And I highly recommend anyone who wants to do any work with the acrylic, try to get the " Acrylic Plus " as I spoke off in the EZ2CY thread, if you can get yours hands on a sheet. Cyro Plastics is the manufacture of the " Plus " but if you get in touch with Cyro, and get the name of the closest distributer to you, they will probably sell you a single sheet if you do the footwork.

    Hope this helps

  6. #6

    Re: Plexiglass cutting

    For cutting straight lines I use my table saw with a fine blade running backwards. For rounds configurations I use a fine blade and I warm the plastic where I plan to cut. For bends I use the oven and only heat what I need to bend and bend it over a form.


    BILL

  7. #7

    Re: Plexiglass cutting

    To table saw plexi use a SHARP blade going forward, not backward. You want to cut the stock, not friction saw it. The number of teeth isn't that important, just remember that you want each tooth to cut about .001" of an inch chip load. If you multiply the number of teeth by the rpm of the saw, times .001", you'll see that you want to feed the stock pretty fast through the machine (cut across a 48" wide sheet in ~15 seconds). If the plastic is melting, you are feeding it too slow. The stock shouldn't be warm after cutting, if it is, speed up the feed rate. Properly done, a table saw cut is ready to flame polish without further sanding or smoothing.

    To band saw plexi, use about a 10 tooth per inch blade, and don't feed the stock too fast, or you'll get chipping on the bottom edge, but feed fast enough to cut, not rub.

    Drilling plexi is done with spade drill bits, or if you don't have access to those, "dub" the leading edge of the drill on a grinder so the leading edge of the twisted flute is parallell with the axis of the drill (similar to cutting brass). Feed rapidly enough to avoid melting the plastic, use a coolant to lubricate the cut and keep the drill cool (water is ok) and back off the feed rate when you cut through the back side to prevent chipping out the back of the hole. If your drilled hole has a rough melted appearance, you let the drill get warm. You MUST keep it cold.

    Machining is done with very sharp end mills, kept wet with oil. Don't try to cut plastic with a dull one, you'll get a terrible finish. If you have to cut with a fly cutter, grind a large radius tool (+.25r) to prevent chipping of the surface, and hold down the feed rate. If the flat surface is chipping out, slow down the feed. High surface speed (rpm) is fine. The same is true when turning. High speed tools diamond honed by hand work best, carbide turning tools aren't sharp enough.

    Flame polishing is best done with an OxyHydrogen flame, but you can also do it with a butane or propane flame. For best results use a "blazer" micro butane torch (sold at hobby stores) and adjust the air control for hottest flame. the object is to melt the surface as quickly as possible without heating the underlying material. Practice with the torch on scrap. Like welding, flame polishing is an aquired skill. If you move too slow, the surface will take on a bubbled appearance. Practice, practice, practice. With enough practice, scratches in the middle of panels can be flame polished out.

    Forming is done at 150F, the slumping temperature. If you form or machine (and then glue) plex without annealing it first, you will get crazing. the annealing temperatue is low, usually about 115F for 8 hours.
    Gluing is accomplished with methyl methacrylate. Fit the parts with .002" clearance, and admit the solvent with a 5cc syringe with a 25 1/2 guage needle. For small parts use a 3cc syringe. The idea behind the small syringe is to give more control over the amount of solvent applied. Remember, that you are not gluing plex per se, but rather solvent welding it. For larger joints, fit the parts with .005" wires every few inches as spacers holding the joint apart. Insert the solvent, wait 20 seconds, and pull out the wires, closing the joint. This will allow time for the solvent to melt the stock, and closing the joint will push out any air bubbles.

    Sorry for the long post, but I've been fabricating plexi (acrylic) and Lexan (polycarbonate) scientific parts for 30 years.
    "The older I get, the faster I was......."

    1979 60C "Ohana" hull# 331

  8. #8

    Re: Plexiglass cutting

    Wow! These are fabulous posts. I'm going to be a lot more confident working with these materials with this info.

    Thank you all very much.

    Ted

  9. #9

    Re: Plexiglass cutting

    Dan ... thxs for the reply. I'm thinking about using plexi for the curved aft corners of my enclosure (1979 43DCMY). These are about 42" high and 14" at top and 18" at bottom. It will be tricky as the top is rounded and the bottom angled to conform to the teak cap rail. I'm thinking about using the heat gun as the sheet will be too large for an oven.

    I'm also thinking about using the plexi for the large side curtain panels (appx. 42" high by 38"wide). I'll either use plexi or Stratoglass for the panels at the boarding gates as they need to bend some.

    My panels are currently bordered with vinyl. I've done some tests with hot glue and it appears to adhere the plexi to the vinyl well ... or I may just use 5200 sealant adhesive.

  10. #10

    Re: Plexiglass cutting

    I forgot to address edge treatment. To get a nice smooth rounded edge to your panels, use a router table with a bearing supported radius cutter. Don't feed the part past the cutter too slowly, or once again you'll melt the part instead of cutting it. Follow up with flame polishing.
    "The older I get, the faster I was......."

    1979 60C "Ohana" hull# 331

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