Plexiglas / Acrylic

Plexiglas is more expensive than cheap acrylic, and used to be much better to work with.These days, it's pretty much the same thing. Plexiglas a registered trade mark of General Electric for one particular amorphous acrylic compound they manufacture.Just like "Lexan" is a trademark for their polycarbonate material. Both terms are often used generically, but they're both trademarks. Note: Polycarbonate is NOT acrylic. ¹. Acrylic can be Laser Cut and poly will burn and smoke in a laser cutter.

Vacuum Forming

Dan Creagan says

Another trick is to use diluted liquid detergent (dishwashing soap) as a lubricant for the saw blade. I use this when I do scroll saw cuts and it works fine. Without it, all I get is a solid piece of plex because the gap in the back of the blade fills in as the cut progresses. With detergent, I have to clean up the saw table a bit after the cut, but it isn't bad and well worth the results.

Richard Ottosen says:

A note about working with acrylic. For years every time I used this plastic I would cuss because it would melt when I used a saber saw to cut it. This occurred at any blade speed. I used a very fine blade to minimize the tooth marks in the cut.

WRONG! On this project I was having the same problem so I switched to the coarsest toothed blade with the most set to the teeth. This is the way to do it right. The the plastic does not melt and the tooth marks are not a real problem since I sand the edge later anyway.

If you have deep pockets the plastic to get is polycorbonate ("Lexan"). It machines just like metal. For instance, when you drill it you get curly cues similar to drilling metal. I have not found this at any hardware stores.

Leo Van Loon says

The trick in machining acrylic (and polycarbonate, PVC or aluminum) is that milling tools must have a NEGATIVE cutting edge side rake. The rake angle of a drill can be simply ground, saws are a little bit more difficult. Circular saws are sold in a 'negative' version, but for a jigsaw you have to file it yourself.

But, do not saw straight cuts, break them. Buy a special tool to cut a small scratch, on both sides for thick plexi, and break it.

For reference here is a summary of the substances recommended for gluing Plexiglas (tm) in no particular order.

• Methylene Chloride
• MEK
• Dimethyl Sulfoxide (DMSO)
• Cynoacrylate adhesives
• Epoxy
• Glacial acetic acid/Acetone 50:50
• Weld-On #3,4 or 5 (from glass shops)
• Plex adhesive (from glass shops)
• Chloroform with 10% dissolved Plexiglas(tm)
• SC25 adhesive from Cadillac Plastics

From Dr. Myke Stanbridge

Hi Griff, just saw the added piece on Lexan, which is a polycarbonate, whereas Plexiglas is an acrylic. The bad smelling plastic that cracks with Loctite, etc., is not either polycarbonate nor acrylic, but a copolymer using polystyrene as its main component; probably a cheap ABS of some sort, but it could also be post chlorinated PVC alloyed with polystyrene - this combo has a nasty smell when drilled, etc. It's one of the 'new' cheap recycled plastics being made in China... Being translucent tends to fit; these plastics are usually a dark milky tint or heavily filled with carbon black. They have a place for cheap domestic and auto goods, etc.

High impact fabric uses Kevlar aramid polymer, which is nothing like polycarbonate. It is true, however, that 'cheap' bulletproof windows tend to be made from layered Lexan polycarbonate...

Plexiglas is just one proprietary name for acrylic thermo plastic. Others are Lucite and Perspex... Chloroform gives the highest viscosity adhesive per dissolved quantity of acrylic. This is important for a dry clamped assembly to avoid fluid runs, drips, etc. The chloroform can be used in a pure state or with acrylic pre-dissolved in it to thicken it, but just 10% acrylic in chloroform is highly viscous...

Suppliers:

• http://www.tapplastics.com/
• https://www.eplastics.com/ Plastics supplier in Kearney Mesa, CA

Also:

• Construction

Comments:

• Yes, the headline is plexiglass, but in this discussion they talk about polycarbonate, which is not plexiglass.+

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