Handling: The most important thing to remember is that care of the plastic while you work with it will help make the finished product look it's best. Keep the paper or plastic covering in place until you're finished working, and are ready to begin assembly. If at all possible, leave the covering on until you're completely finished. In fact the paper covering makes the best masking for painted effects, just trim away the portion that you wish to paint with a razor knife.

Budget cutting: Plastics up to 1/4" thick can be cut by hand using a scoring knife, available at most home improvement and hardware stores for under $10. Stanley makes a good one, part# 10-599(knife), 11-942(blade). The blade is the key to how a scoring knife works, it has a weird hook shape that scrapes a thin line into the plastic, allowing you to snap the pieces apart. I use these for quick projects, when accuracy is not an issue. However with a little practice you can do some really good work using one of these.

Cutting: If it cuts wood, it'll cut plastic. Things to remember though, use a sharp blade, and take your time. The extra heat that builds up from exerting too much pressure against the blade will cause the plastic to melt and gather in the kerf(the slot made when you cut).

Take it slow, if you are using a jigsaw, try and use a hollow ground blade, you'll be able to tell these from other blades by their appearance. Hollow ground blades have machined sides, and very sharp teeth, they are designed to cut with the teeth only, without the blade body coming in contact with the stock and building up any extra heat. They cost a few bucks more, but they're worth it.

Circular saws and plastic, once again take it slow. Make sure to adjust the blade height, the blade should clear the plastic by no more than 1/4", I use a standard carbide tipped combination blade to rough cut the sheets of plastic into pieces for fabrication. Remarkably, the rough cuts are quite smooth and would pass inspection, in most cases. Just take your time, unless the edge is going to be polished, and in direct view, this may be all the work that is required to finish your project.

Routers, fabricators best friend, when used with a straight edge and carbide bit, routers produce the cleanest cuts, requiring the least amount of sanding. In some cases you can polish the trimmed piece without sanding at all. Let your imagination run wild, use different types of bits for edge effects, Remember to keep the speed high, if you have a variable speed unit, and bit sharp.

If you are going to be doing lots of plastic work, and have access to a table saw you'll want to get a good blade, 60 to 80 teeth, if you can find a TCG (Triple Chip Grind) blade, buy one, if not then the standard ATB(Alternate Top Bevel) will do, requiring a little more finish sanding or final trimming with a router. Freud makes one of the best ones available, the LU98 makes the absolute cleanest cuts due to it's Teflon coated body. This blade can be found for around $80, and is worth every penny, don't worry though it is a good all around blade, I use it as my primary blade in all of our table saws in the shop. It is capable of cutting wood, plastic, and aluminum, with extremly smooth cuts.

Drilling: Slow again, different approach in tools though. To drill through plastic you need to scrape, not cut, away the contents of the hole. This is done with a specially ground bit, standard drill bits cut away the stock. This cutting action will pull the drill bit through plastic, and force it out the other side, kinda like an exit hole from a gunshot, nasty results for your project. You can make a plastic bit by filing the cutting edge of the drill bit to a flat surface in-line with the shaft of the bit. No matter what type of blade you use, you should always place your project piece on a piece of scrap wood, this will help to support the area around the hole and keep the bit from bursting through the other side.

Sanding: Work your way towards 400 or 600 grit wet sandpaper. start out no lower than 100 grit, only if you have deep gouges to remove, preferably no lower than 200 grit.
When using the wet paper, remember to use plenty of water, it will help to get the best results.

Polishing: Buffing a well sanded piece gives excellent results, nice clear shine, and durable edges. Use a bench mounted grinder with buffing wheels(loose bound for plastic, tight bound for metals), and mild to fine(tan or white) polishing compounds. If you cant find a loose bound buffing wheel (buff), just remove all but three or four of the center rows of stitching that holds the wheel together. Apply the compound to a spinning buff, and polish the plastic using light to moderate pressure against the wheel. Be careful not to hold the plastic in one place too long, the spinning wheel will cut into the plastic, ruining the project. Another way to polish the edges is to use an open flame, this method requires a lot of practice, and can easily ruin a project, so if you're going to attempt this, play with a scrap piece and get to know the limits and reactions of the plastic that you're working with.

All of these hints will work with cast and extruded acrylics alike, but the polishing will not work with Lexan, it requires a gas vapor to be used in the polishing process.

Hope this helps,
L8,
Mike

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hometown.aol.com/mjaxxl/myhomepage/howto.html
audioexpressusa.com
Mabeita@audioexpressusa

It's really good to see someone that enjoys this stuff enough to share with others too. And also GOOD ENOUGH to be ABLE to share the RIGHT information.

Keep up the great posts!

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quote:

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Originally posted by sqbronco:
Just curious, why do you only say to use up to 600 sandpaper? I have only done 1 plexi project, and don't remember how high I went, but would a higher grit give you a smoother finish? Without your response, I am assuming that the buffing wheel takes care of the rest, is this correct?

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jimmyo007: My very first plexiglass project was polished entirely by hand, it took three solid days of sanding with successively finer grits, until the final step of polishing, also done by hand.

J_P: There are many different types of glue that I use on plexiglass, each one has different properties for different effects and assembly methods. Weld-On makes a line of solvent adhesives that work extremely well, the most common of these adhesives that I use are #4 and #16. The #4 adhesive is great for most applications, it is a fast setting liquid solvent adhesive that will join Plexiglass and can be used in a dip and set method to edge join pieces with ease. The dip and set method that i've spoken of, softens the edge of one piece by placing the edge in a shallow metal or glass pan with a bed of solvent(1/16" - 1/8")for about 30 seconds. When removed, the plastic will be soft on the edge, and can be pressed into position and held for another 30 seconds, until set. The resulting joint will fully cure in about 4 hours.

The #16 adhesive is a gel type solvent adhesive that allows extra working time, as it sets at a slower pace. It is good for gluing flat panels together, because it will fill areas fully allowing better adhesion of wide areas.

To hone your skills of working with Plexiglass, experiment on a few small projects, it is easier that you'd think, once you get used to the materials own limits.

Once again, Hope this helps.

L8,
Mike

Also, are there any glues that will bond plexiglass to other materials, like glass or metals?

Thanks!

Best Regards,

Dan

Dan

quote:

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Originally posted by [meph]:
you can also make plexi corners by heating and bending.
easiest way i've done it is by heating up a metal pipe and putting the plexy near it. you can buy these kinds of things to. they just make it easy to heat only a certain part. (The narrower the heated part the sharper the corner will be)

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A bending table can be made out of an old electric space heater. Preferably the type that has either a steel, coil or band type heating element.

You start with a piece of aluminum U-channel(3/4" x 3/4")about 36" to 48" in length, depending on youp expected needs. Mount the U-channel in a work bench or small portable table top, take apart the heater and use the insulators to mount the heating element in the U-channel(trim if necessary). If the space heater has an adlustable temperature control it should alos be wired into the bending table.

Once the unit is wired up and plugged into the electrical outlet, this is the hardest part, turn it on and watch it begin to GLOW.

If everything has gone OK, then you'll soon be able to bend plastic, up to 1" thick, in very straight lines. With the unit powered up, place a piece of plastic over the heating element. Wait while it warms to a suitable temperature, testing occasionally to see if it is pliable. When you feel the tension begin to ease, and can slightly bend the plastic sheet, turn the piece over and heat the other side for about 15 seconds. This will insure that all the internnal stress has been relieved, and allow a clear, crack free fold.

Hold the folded piece in position while it cools, depending on the thickness of the material, this may take up to 10 minutes. Not to worry though, if you keep a fan or source of compressed air nearby, you can use this to cool the plastic quicker. Water can also be applied to the fold after about 30 seconds of air cooling to speed the process even more, without any harmful effects.

If you need more details, just e-mail me and I'll send you what you need.

L8,
Mike

On a serious note, Mabieta, I think what you're doing is awesome and I know I appreciate your effort to help all of us out. Keep up the awesome work.

when it is heated and bent, does the bend have a frosted look to it or does it retain its transparency?

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Craig R. Collier
1996 S-10 Blazer
Soon to be:
Kenwood eXcelon 915
Rockford Fosgate 600a4
Rockford Fosgate Fanatic Q 6.5" components
Rockford Fosgate Fanatic Q 6.5" components
Audiocontrol Epicenter OR Phoenix Gold Bass CUBE
2 Rockford Fosgate bd1000a1s
2 Rockford Fosgate Power DVC 15s (ported)

Don't be in too much of a hurry when trying to bend a sheet of plastic, the center of the plastic needs to be heated as well as the surface, if not heated completely the plastic could have small cracks develop across the length of the bend. You can tell when the sheet is ready to fold by the appearance of the plastic in the heated area. Look for the plastic to swell slightly, it'll take on a magnifying property along the heated area, sort of like a line magnification ruler used by bookkeepers and accountants.

Bending is harder to do on thick sheets, but with a little practice on some scraps it gets easier, and looks really cool.

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The all-mighty '91 Shadow

-Alpine CDA-7838(soon to be a Kenwood X715)
-a/d/s/ A5is components
-Audison VR206(75Wx2) for the tweeters, a/d/s/ P640.2 for the midbasses(120Wx2)
-2 Eclipse 88120.4s
-MTX 2400X(600 grossly underrated watts) for the subs
-PPI PSC-221 Phase Shifter and Audison SXR3 3-way x-over

The plastic used in scale models is comprised partially of steryene, a component of styrofoam, this usually reverts to its processed color state, a milky white color, when exposed to the adhesives necessary to bond pieces together.