Help, please: Engraving on Lexan

[Jim P]

Maybe someone can give me some advise and I can cheat the learning curve on graver shaping and or sharpening
I use Steve Linsey's graver sharpening system for all my gravers and it works great for metals but I need to do some cutting on a motorcycle windscreen that is I'm sure Lexan. I did a few trial cuts and wow is that stuff soft? I can cut it fine but the problem is I'm haveing trouble with the graver wanting to cut to deep and having trouble getting the graver to pull out of the material. I was going to try putting a much larger heel on a graver and try that but I thought I would see if anyone has found a configuration that works well on Lexan.
Thanks ahead of time for any help.
Jim

 

[JJ Roberts]

Jim, What is Lexan and motorcycle windscreen?never heard of it. J.J.

 

[dlilazteca]

It's a very light but sturdy clear plastic, if thick enough its used to make bullet proof windows

Carlos De La O III

 

[Ron Spokovich]

In general, and I've cut a lot of each on the mill and lathe, Lexan is a polycarbonate and formulated to flex and not shatter. It's used in safety glasses, windshields, and some bullet resistant applications. The other stuff, I believe named Lucite, is an acrylic, and is much harder, will shatter, but gives good results when it must be polished as in the making of lenses. Polycarbonates, by nature of their chemistry, are a gummy material and probably won't give good results regardless of tool geometry.

 

[KCSteve]

You may just have to go with developing a very light touch. Some folks - like Phil Coggan - do a lot work with no heel at all and when I've tried it the only way I could get it to work was to sort of pull up while cutting. It's not really pulling, it's more of you keeping the graver at certain depth rather than the graver tending to hold a depth by itself.

 

[pilkguns]

I would use a high speed rotory burr to work on lexan, plexi or glass. diamond is necessary for the last. I used to do a lot of custom car windsheilds and mirrors and windshields on tour buses in Nashville.

 

[monk]

i agree with scott- there's lots to be said about the use of rotary tools. this would, i feel, solve your problem. don't even think of the dreml. too much runout (wobble) at the tool point. i'm not usually a fan of harbor freight tools. having said that, i bought a 50k rpm, pencil type air tool. about 20 bucks when i got mine. not a world class tool, but has a reasonably stable rotation. if you already have a compressor, this tool may serve you for that job.

 

[silverchip]

I am not sure bout Lexan but I used to engrave on Plexiglass to make pantograph patterns using a 52-3 round bottom graver.

 

[Jim P]

Wow that's cheap! I think it is anyway. Yea I have a good high CFM compressor that will handle a rotary tool and it's been along time since I have priced them but as I recall the rotary tool was so high priced that I sorta gave up on that idea. I have a dremel tool but it's awfully clumsy as am I and the combination of the 2 and I'm afraid I would be buying the guy a new windshield.

 

[dlilazteca]

You can always buy a shofu from graphictransfer.com and use paypal bill me later for payment a superb rotary tool.

Carlos De La O III

 

[monk]

the one from harbor freight "eats air". it takes a good deal to keep the tool working, but for a one-time-use, it's probably the best option. i don't have one of the more pricey jobs, such as the micro-motor. then again, if i had a real need for something better, i'd just steal more grocery money to get it ! stolen grocery money is how i bought all the toys i have !

 

[hankpope1]

Make your graver from round drill stock with about a 55% face angle, it cuts Plexiglas great the thicker the stock the more shallow the cuts.

 

[Jim P]

So I searched and got a good idea of what all is available as far as roteary tools go. Electric are
Slow and fairly expensive for what you get. 1/6" tool size is the way to go but there isn't much of a price selection. If your going to spend the money on what you have to give for a cheapy 1/6" tool you might as well go ahead and get a good one. There is a wide varity of 1/8" chuck size of air driven tools and you can get them as cheap as $20.00 for the really delux models but for some reason they don't have a very good warranty? Imanage that? Anyway seemed to me like a good idea to not spend much and get a sorta decent 1/8" chuck air driven tool and I would have something that turned a decent speed and should last long enough for me to get used to a rotary tool and decide if it was something that would be useful enough to justifie spending the $500.00 to $600.00 it cost to buy the setup from GRS and have a top of the line setup. Amazon .com and a c/c and a few days later I was turning practice plates in to junk. It seems that the rotary type tools and Jim have a long way to go to get where I can set down and draw some lines on a Lexan wind screen and cut them with a rotary tool the way it is done with an air powered hammer type hand piece. I can see where it would be much faster for background removeal and I'm sure that after having one that there is a million uses for one but it certainly isn't a replacement tool for a 901 hand piece. It's gonna be a while before I plop down $500.00 bucks for a good one but I'm glad I spent a $150.00 for a useable 1/8" air drive and a set of carbide bits to have to use for the things it can be a help and maybe save a little time. Thing to keep in mind is they are fast but they can sure turn a job into junk in a really big hurry also.

 

[monk]

my go to compressor for such work is a 7.5hp ingersol rand. it has an 80 gallon tank. have even done a couple of granite tombstones ( rubber blasting mask) with the compressor. needless to say the hf pencil rotary tool offers no challenge to the compressor in keeping up with demand.