Plexiglass Cutting

You can run this on the table saw if you have tuned your machine to run near vibration free and used a fine tooth blade. Carbide with zero rake like a blade for aluminum and SHARP. If it is the softer plexi the edges should be near chip free. The harder acrylics tends to micro chip at the edges. Cut over size and hand scrape the edge to size. A fast moving flame will help clear the edge.

I've watched a pro cut and bend acrylic for boat windshields a dozen times and I'm still amazed how easy he makes it look. Its more of an art of feel than science.

If you use the router method, use a spiral cutter either up or down (user preference) and straight edges to control the cut. The bit will try to jump if you try to free hand it.

Check with your acrylic supplier for solvents. They will help to clear the edges of imperfections. Just don't touch the edges till the solvents have completely vapored or you'll leave finger prints.

Good luck

Jim Vrzal Holiday, Fl.

I've just recently replaced the windscreens in my tailwind in 3mm plexiglass. commercially the stuff is cut with a carbide tipped circular saw. I used my table saw with the carbide tipped wood blade that has been in it now for over 10 years. curved areas I cut with the bandsaw using a wood blade. each surface was then edge sanded on a horizontal linisher. did a beautiful job.

if you ever need to taper the edge I have done this on a piper cherokee replacement windscreen. the guys used a thicker material then found it wouldnt fit. an angle grinder with a new metal cutting disk, blunted off a little by grinding across a brick, does a very near perfect job if used with a very gentle touch. most areas of the taper came out transparent off the tool.

the sanding and grinding heats the edge which anneals it.

fresh plexiglass is a pleasure to work with. I think most of the horror stories come from using old bits that have been laying around for years.

if you need to drill it use a piece of MDF as a backing piece and dont let the plexiglass rise off the backing board. a sharp drill with very gentle feed worked for me in a drill press.

buy a piece of scrap and have a play. it is nothing to be afraid of. Stealth Pilot

"Plexiglas" brand IS cast acrylic. The only 'softer' clear plastic glazing I can think of is polycarbonate -- Lexan. Lexan requires slightly different cutting techniques, and is ruined - permanently de-polymerized - by almost any chlorinated solvent.

Plexiglas and other acrylics cut fine with (as you said) a fine-toothed, low rake carbide blade. Run it slower than for wood to help prevent friction heating, and keep cutting continuously. Allowing the blade to dwell in the work will always result in a melt/burn.

Edge touch-up is best done by first using progressive abrasives. This often will give you as good a finish as you desire. If not, then _soak_ the edge (only just the edge... don't let the solvent up on the faces) in methylene chloride for a few moments, then quickly shake off the excess, and allow it to dry in a dust-free, low humidity environment. It'll come up as clear as the faces, albeit a little "wavy", like float glass.

LLoyd

I've cut it on my table saw using a fine tooth blade. Needed to cut VERY slowly with 1/8" plexi to prevent chip out until I realized I finally had my excuse to make a zero clearance insert and then it was no problem.

Steve.

| > How do professionals cut plexiglass? I am going to need to cut some, as | > well as route some of the edges to make them fit into slots. | | Many people use a carbide-tipped tool to score the sheet, which is then | snapped off by bending the scored line over an edge. Just like cutting | glass. This leaves a very clean edge. |

I've used this technique many times for relatively thin plastic of almost all types, but never for anything thicker than .100" or so. How would it work (if at all) for .220" Plexiglas?

Norm

Slow as in feed or SFM? Would a fixed-speed (4800 RPM) cheapie Ryobi saw (USD $170 or something like that at Home Depot) do a really good job with a nice USD $50 Oldham 100 tooth carbide saw blade? Maybe need blade stiffeners? I'd like to some small production lots of 3-6mm thick transparent Plexiglas.

Best regards, Spehro Pefhany

Just fine! I make the score very deep with multiple passes with a home-made scorer'er.

Many people use a carbide-tipped tool to score the sheet, which is then snapped off by bending the scored line over an edge. Just like cutting glass. This leaves a very clean edge.

How much must be taken off for the sheet to fit into the slot? I assume that the slot width isn't a common sheet-goods thickness.

Wet sanding works very well.

If you need to drill holes, flood cooling with water is very useful.

The intent is to keep the plastic from melting from the friction and gumming things up.

Joe Gwinn

Slower SFM. If you have just a bit of set on the teeth, rather than a narrow-kerf blade, you can run pretty fast, but since the material is cooling the teeth, you have to adjust your feed rate to keep the blade and plastic cool.

If your teeth have any appreciable set, you'll need to cut a few thou. large, and abrasively clean up the edges.

LLoyd

I've been using a non-ferrous carbide blade from Tenryu or a plastic-rated blade from Forrest to cut acrylic sheet on a Hammond Trim-O-Saw, which is a sliding table saw. The saw was used a few decades back by printers to cut lead slugs. The finish is smooth enough for my purposes but by no means dead smooth. Square/rectangular pieces come out with opposites parallel to

Here's a picture of the swan edge on some 1/4" acrylic sheet cut with 3 different blades - the Tenryu cut the middle one:

"Steve B" wrote in news:JV0%f.386$QP4.328 @fed1read12:

You can get a table saw blade made specifically for acrylic with the proper tooth shape and set. They are REALLY expensive. An 80-tooth triple-chip carbide blade is very close, and will produce just about the same results.

The real secret (which I haven't seen mentioned here yet) is to scrape the edge after sawing, rather than sanding. Take an old hack saw blade and grind the back edge flat (perpendicular, lengthwise on a belt sander works best). Clamp your piece vertically, stand at one end, hold the back of the blade across the work edge with both hands and draw towards you. Think 45-degree negative-rake lathe tool. When you get the angle, pressure, and speed right, it'll make sort of a hissing sound and leave a near perfect finish. Expect to practice a lot if you haven't done this before.

Then you can move on to flame-polishing, buffing, or gluing. Pick only one though. Particularly don't flame-polish, then glue. The acrylic will craze on you.

- Bruce

snip------

, albeit a little "wavy", like float glass.

Did I miss the boat? Isn't float glass lacking in waves? That's why the process is used---because it makes flat glass.

Harold

Yeah.... duh! CAST glass.... like the old 1800's stuff.

LLoyd

Chuckle!

You an old fart like I am, Lloyd?

I find I'm saying things that make little sense with regular frequency. I don't recall doing that as a young guy---but then I knew everything then. :-)

Harold

HEY! I resemble that remark!

LLoyd

Mark Twain said something like - I have a good memory of my youth about many things. Most of which never happened.

Steve