I was asked about laser engraving of plastics, for use as dial scales, and thought it worth forwarding to the list.
It seems that just about any sign, rubber stamp or trophy shop these days has (or has access to) computerized engraving equipment. Some use mechanical engraving, and some use laser. Mechanical engraving seems limited to low aspect (low depth/width) ratio marking, while laser engraving can be used to etch very precise high aspect (high depth/low width) ratio markings, and can even cut directly through the material within (nearly) the laser beam diameter! Some shops use equipment without a computer interface, similar to a copier machine, that scans a black and white image on paper and simultaneously rasters the laser beam over the material being etched. Other shops use computers with software that allows the shop to import files, type in text and import images, that the computer can then direct the laser to etch. Laser etching can deeply etch wood and just about all plastics (even clear Lexan or Plexiglass.) It can also be used to remove dark paint or anodizing from the surface of metals, to reveal the shiny metal beneath. Mike Shaw just earlier mentioned Traffolite, a multi-layered multi-colored plastic, primarily used for making signs. This could be used very well with laser engraving, where the power of the laser can be instantly adjusted to control etch and exposed-layer depth, and thus coloration. Depending on what you are trying to do, laser etching can be a reasonably-priced method to make parts for your sundial. If you can draw a scale or artwork by hand, or print it off from your computer, you can have the image inexpensively copied / laser etched with fair accuracy directly onto a flat wood, plastic or metal surface, which may then be permanently fastened to your sundial. I went a slightly more expensive route for the New Millennium sundial I am making. Because I am having the sundial commercially cast (in a quantity hopefully greater than one,) I desired a very precise original model. The sign shop I went to uses a computer, and an accurate laser engraver very similar to a drafting plotter. I did all the design and layout work on my PC, took my drawing files to the sign shop, then worked with the shop owner using his graphics and laser software to eventually optimize font placement, laser power and etch characteristics. I wanted very good control of line precision, width and depth, as these etched markings from the original model will be transferred directly to the mother mold, and in turn will affect the final castings. I was very pleased with the final pieces the sign shop turned out. The total bill was a one-time cost of about $250, to produce a very clean, accurate analemmic face plate and equatorial scale for the original model and for all of the subsequent castings. This is much cheaper than I could ever have had a blank bronze sundial engraved for, let alone multiple sundials. Hope this helps someone. Pete S. email: [EMAIL PROTECTED] home: http://netnow.micron.net/~petes/sundial ----- Original Message ----- From: charlie mead <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, March 05, 2000 9:25 PM Subject: New Millennium Dial > I too fool with a similar dial, a take-off on the Smoyer dial. I am > more than curious about the 'laser engraved plastic' scale ( the scale > has always been my downfall in dial making). > > Would you share your knowledge on how to do this with 'laser engraved > plastic' ?? Like what kind of plastic etc. > > Charlie Mead > 136 Emerald Cove Lane > Rockwood, TN 37854 > (423) 354-1993 > 35.85 N. 84.69 W. > >
