I want to make up some jig I've seen on Youtube but they don't say what they are cutting up. The mortising jig shows two things. The clear looks to be 1/4" and cuts well on the table saw plus routes well. Would plexiglsass work well? The other thing being being cut is white and looks to be at least 1/4" but possibly thicker. It is used to make sliding stops. I have tried cutting up a kitchen cutting board before and it came out with almost a melted edge.
I do like the videos where this list the materials.
Re: Plexiglass, Acrylic, Cutting Board What To Use?
Mark, I think acrylic is plexiglass, which is harder and breaks more easily, then Lexan is a brand of polycarbonate, which is tougher in strength, but scratches more easily, and probably a better choice for a template.
There was a discussion on here a few months ago that I recall someone mentioning installing polycarbonate on a machine for safety, but later the screws all had cracks running out from the holes. While this looks bad, it is due to over-tighting, but not anywhere near failure. I picked some off a machine a while back that showed the cracks. When I cut off about 3" then put it in my machine vice and tried to break it off the last 1.5", I couldn't get it to break, by bending it way over. Rather than flat head screws with the cone shape counter sink, I'd suggest pan head screws with flat counter sink, then just snug the screws.
As for melting, you MUST have a clean sharp blade, and not feed too slowly. Any pitch on the side of the blade tooth will prevent a good cut. If your cutting thin polycarbonate on the table saw with a wide gap in the table insert, there is a real danger of the plastic starting to resonate, side welding of the melt, then get a kickback.
A good safe way if you don't have a good blade is to jigsaw outside the line, with a slow speed stroke, and fairly fast feed rate, then use the router or power-plane, or even jointer to straighten.
UHMW may be the white plastic that is slicker. It cuts easily and even hand planes nicely.
Re: Plexiglass, Acrylic, Cutting Board What To Use?
Poly(methyl methacrylate), also known as acrylic or acrylic glass as well as by the trade names Crylux, Plexiglas, Acrylite, Lucite, and Perspex among several others, is a transparent thermoplastic often used in sheet form as a lightweight or shatter-resistant alternative to glass.
Lexan is a brand of polycarbonate which is more flexible and more shatter resistant than Plexiglass.
Plexiglass tends to be brittle and will not machine as easily as polycarbonate. When machining polycarbonate you want sharp blades and a fairly fast feed rate. You can run 1'4" and thicker polycarbonate across a jointer.
When working with either material you want to smooth all cut edges by sanding and polishing either mechanically or by flame to eliminate any small nicks in the edges. Pan head screws with a rubber washer work best to hold plastic to something else. You want firm pressure but not so the plastic distorts.
Take a small piece of plexiglass and hold it up so that light comes from the back look at it with your polarized glasses. Then do the same thing gripping the plastic hard with a pair of pliers. Those colors that you see are stress in the plastic. You want to avoid creating those colors in jigs and fixtures.
UHMW and HDPE are plastics from the same family of polyethylenes. UHMW is more wear resistant and slippery than HDPE.
Lee
Re: Plexiglass, Acrylic, Cutting Board What To Use?
For making jigs and patterns I cut mostly acrylic and other plastics on the bandsaw. I use the same 1/2"x3TPI blade as I do for processing green wood and thick turning blanks since I'm too lazy to change it. It cuts perfectly every time although the edges are not smooth. I clean up the edges as needed with a file, sanding stick, or disk/belt sander.
White HDPE is great stuff to work. It cuts well on any kind of saw and machines beautifully on the milling machine, metal, or wood lathe. Resaws nicely into thin sheets but I haven't tried running it through the planer or drum sander. I've made a variety of fairly precise brackets, special washers, insulators, and other parts from it. Fortunately, I found a couple of 1" thick sheets about 4'x8' with some big shapes cut out but plenty left - they were so cheap they were almost free at a scrap yard. Do you need a piece or two to play with?
I also found some thick green plastic, coarser in texture with some white flecks in it that look clear in the microscope. A bit of research and the flame ID test convinced me it's a fire-retardant HDPE.
JKJ
Re: Plexiglass, Acrylic, Cutting Board What To Use?
Kieth - You are correct . Polycarbonate is tough as can be. It is used for bullet-proof panels in banks and such. You can bend a piece double and it won't break. However, it is very sensitive to some chemicals. The radial cracking that is often seen radiating from screw holes is generally due to use of an inappropriate thread locking compound. The chemicals in the compound cause cracking regardless of fastener torque. Don't believe you can cause similar cracking without locking compound, regardless of torque. Ensure the label on any proposed thread locker specifies compatibility with the specific plastic you intend to use. In another life when I managed a small R&D machine shop, I kept a sample of polycarbonate with the radial cracking at screw holes just to convince skeptical customers and engineers that their "mysterious" cracking failure had a simple solution. The only other common problem with polycarbonate is that, unlike acrylic, it is difficult to polish.
Re: Plexiglass, Acrylic, Cutting Board What To Use?
PS - To answer the original post, I use polycarbonate whenever I can. I like the additional toughness. No matter what I do, it won't fail as acrylic sometimes will. If you cut a lot of plastic, it is worth buying a blade specifically for that. They have optimized tooth design to reduce or prevent melting, grabbing, and chipping at the cut line.
Re: Plexiglass, Acrylic, Cutting Board What To Use?
My BIL used to sell lexan for GE, worldwide. He used to have a coffee table with 9 9mm bullets buried halfway through the top. The top was dimpled but not penetrated through and through.
Re: Plexiglass, Acrylic, Cutting Board What To Use?
Working with thin sheets of plastic, including HP laminates, can be a pain on a table saw. Use a piece of 1/4" ply 1" wider than your cut and an inch or two longer than your saw table's width. Set the fence, drop the blade, place the ply tight to the fence with a nail thru the overlap on each end (to prevent the ply from sliding). Turn on the saw and elevate the blade up thru the ply to make a zero clearance surface. The ply then insures that the thin sheet will not catch or jam in the gap between the fence and the table top.
You get a nice clean cut on the material.
Re: Plexiglass, Acrylic, Cutting Board What To Use?