I'm trying to do some custom work with Lexan. I bought a cutter that was similar to a glass cutter, where you just score the lexan and break off the peice. It doesn't really leave a nice cut and I'm looking to round the edges a bit. Anyone done work with lexan, what do you cut with????

Thanks

what little I've done with Lexan has been the same way - score & break
any bits I've used or blades I've used insantly melt the plastic, and clog the bit/blade
for a smooth edge, I just cleaned up the rough edge....tho, you can do many passes for a deep score, which will make a cleaner break. and scoreing both sides works to, but when they dont line up just right, makes for a worse edge

I've had decend luck with a dremel and plastic but I've never used it on lexan before. Still might want to try it.

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Low 14 sec 99 Pontiac GTP, 3.2L V6 4 sp 86 Fiero GT

Saber saw with a fine wood cutting blade works too.

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I've used the saber saw method and used a grinding wheel at a low speed to shape it.

Earl

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1986 FieroGT now a 4.9

Lexan can be cut on a table saw with a fine tooth blade, a fine tooth blade made for aluminum,
or a good quality carbide blade with medium or fine teeth.

It can be cut with a bandsaw and also a jigsaw but the tooth size and speed at which you cut can simply melt the cut and cause the pieces to stick together.

As for finishing the edge, you can run it across a planer or use formica trim bits on a router.
If you have a planer, this method works well.
I recommend the router method. It makes the best edge.

You can then flame polish the edge with a propane torch to make it glossy.
Also you can wet sand the edge with emory cloth or sandpaper to get a smooth shiny edge.

I normally use a jig saw with a fine blade. You have to go slow or the lexan will fuse together behind the blade and it will still be in one piece when you are done.

I cut it nearly everyday at work. The recommended travel speed for polycarbonate (Lexan)and acrylic (plexiglas) is around 18 meters/min. This is with a round blade, such as a table or skillsaw, not a jig saw. If you want a perfectly smooth cut, with no chipping on either side, sandwich the plastic between 2 pieces of 3/8" mdf or scrap particle board as backing boards. Even plywood will work.Align two adjoining edges on all 3 pieces, c-clamp it together, and trace out your pattern on one of the backing boards. The backing boards prevent the chipping because the plastic can't chatter or vibrate up and down. A good cut may reveal slight visual tooth marks, but you shouldn't be able to feel them with your finger nail. This makes it very easy to flame the edges to a perfect finish without sanding beforehand. Sandwiching it allows you to use just about any blade, even 'coarse' tooth blades and large kerfs, either with a jig saw or circular blade. The same holdstrue when boring holes. Make sure you have something under it to prevent the hole from "breaking out".

If I'm doing it at home, I almost always 1st cut out my pattern on a piece of 1/4 or3/8" mdf. I then use double sided carpet tape (available at walmart) to hold my lexan/plexi down to the pattern and use a router with a bearing bit to cut out the actual part. The router bit will always give you a better edge than a saw cut.

A bearing bit is preferred over a flush trim bit, because the flush bit will easily build up enough heat to score into the lexan due to the high rpms router usually turn. The outer race on the bearing bit turns against the lexan only as fast as your router travel speed.
The downside to the bearing bit is that you cannot make a very small or 'tight' radius with it.

The reason the little scoring gizmos don't work very well on Lexan is because lexan is polycarbonate, and is very pliable, as opposed to acrylic which is very brittle. They work just OK on acrylic, because it will shatter if bent very far. You can take a piece of 1/4" Lexan and bend it back on to itself and it won't break. This is the reason Lexan (a trade name for polycarbonate) is more expensive than Plexiglas (trade name for acrylic). Much easier to work with poly.

[This message has been edited by maryjane (edited 09-17-2005).]

quote Originally posted by maryjane: I cut it nearly everyday at work. The recommended travel speed for polycarbonate (Lexan)and acrylic (plexiglas) is around 18 meters/min.

Don, there must be a unit problem here, 18 meters/min works out to about a foot per second. I can't believe you can cut lexan that fast.

No problem Jonathon. I use a big panel saw, with a very coarse toothed carbide blade, but have done the same with a tablesaw, skillsaw and a conventional blade. 18 m/min is the manufactor's suggested feed rate. Using a fine tooth blade causes problems, as you have too much tooth contact for the speed of the saw travel. Trust me on this as I have undoubtedly cut up thousands of 4x8 and 5x8 sheets of the stuff in the last 5 yrs. Whether it be a recip saw or circular blade, you want each tooth to pull a chip as you move along. That's each tooth on the blade. Allowing the blade to travel along too slowly means the individual teeth aren't actually cutting each revolution or stroke. Comparitively speaking, the teeth are "lingering" in one place. This builds up heat, and results in melting the Lexan back together behind the cut, and very rough and whiteish looking edge. If each tooth is cutting fresh material each time it comes it's turn, it is cutting cool material, rather than just moving around or up and down with the chips from it's previous cut. With a newly sharpened blade, I can cut at a much higher travel or feed speed, but usually don't because it dulls out the blade too rapidly. I am generally cutting up several sheets of material at one time, stacked one on top of the other. It depends how thick it is. 1/8", I can and have cut up to 10-12 sheets at a time, on our big panel saw. 1/4" about 5 sheets. A table or skill saw doesn't have the HP to do this but I can cut 2-3 sheets at a time. When you are making thousands of parts/day, like we do, you have to cut multiple sheets at a time.
The same holds true with a router bit. You have to move it along fast enough so each time the bit rotates, it is pulling chips, and this holds true for metal as well as plastics. Many people move too slowly and end up with a burned edge.

Think about how fast your blade is rotating or reciprocating, and you will understand what I mean about linger time. It isn't atually stopping in one place, but it is moving so slowly, that it isn't actually cutting on each tooth pass either. You have to match the feed rate to the tooth/cutter speed. It's the most important thing in machining and cutting.

Didn't I give you some bronze tinted plexi at San Antonio? If so, that was cut just as I've described above. I had a bunch to give away, just can't remember who wanted some of it. If I did, look at the edges.

[This message has been edited by maryjane (edited 09-18-2005).]

ive had good results with a table saw and sandpaper.

Electric sheet metal shears.

When cutting, use masking tape (good quality) on both side of the area you are cutting. This will eliminate/reduce the chipping associated with cutting. Plus the tape allows you to draw the line you want to cut along. I've had good success using this method.

Hey all. Listen to Mary Jane. I work for GE Plastics, the folks who bring you genuine GE LEXAN Polycarbonate! The scoring method will work, but takes forever. When using power saws, tape both sides to avoid chipping. For those of you that live down South (and maybe up North by now), visit your local Home Depot. They are selling Lexan and Acrylic for home use along with cutting tools for the PC.

And root for Matt Kenseth! GE Lexan is an associate sponsor (on the rear TV panel) on the # 17 Dewalt Roush Ford Taurus.

Good luck with the Lexan. If you run into any serious issues (specific or whatever), either drop me a note and I'll ask the right people or go to gestructuredproducts.com for tech assistance.

John

quote Originally posted by maryjane: Think about how fast your blade is rotating or reciprocating, and you will understand what I mean about linger time. It isn't atually stopping in one place, but it is moving so slowly, that it isn't actually cutting on each tooth pass either. You have to match the feed rate to the tooth/cutter speed. It's the most important thing in machining and cutting.

Don, I have no doubt about your skills and experience, I just never thought to cut lexan that fast before; I thought it was a mistake. The peices I work on are usually pretty small and so I go slow not to mess up. But I am going to be cutting my side windows here pretty soon and I really don't want to mess them up given how expensive they are to replace.