This is Scott Landon's shop made indexing jig for use with the Epilog Mini Helix 45 Watt laser engraver (18" x 24" capacity).
And these are some of his indexing wheels - that he cut with the laser
Here's the computer graphic that was burned in the piece in the indexing jig to the right. Epilog provides a "printer driver" and in your graphics program you select the Epilog as your "printer". Unlike an actual printer you have several other "print parameters" to specifiy - beam power, rate of beam pulsing, whether you're engraving or cutting, etc. Then you just "print" to the Epilog. For this example, which is shown at about 1:1 scale, it took about 20 seconds to "engrave" the pattern on the piece.
And here's the jig in the Epilog with a piece about to have its top edge "wave cut". The table under the indexing jig's platform can be raised and lowered (range is about 10" - I think). The V shaped metal thing touching the top of the piece is used to set the piece to the laser's Optimum Focal Length (Minimum Beam Diameter). The little reddish orange dot on the edge of the piece (behind the V shaped metal thing) is an aiming laser - doesn't burn or cut -used just for "rough" alignment of the piece to where the beam will burn/cut.
When you're ready to actually use the cutting/engraving laser beam you hit PRINT in your software application and the laser's bright white beam, less than a sharp pencil's line width, begins cutting. In this example it was cutting through about 1/4" of redwood. For this example it took less than five minutes to cut this wave edge on the piece which is about 7" in diameter - and that includes manually indexing the piece between cuts and telling the computer to "print". The actual time to cut each "wave" was under two seconds.
There are constraints you must accomodate when using the laser on a curved surface. The beam has an "effective" focal length that will produce a range of line widths that appear the same. Beyond that effective focal length the beam starts to "bloom" and the crispness of the line begins to degrade rapidly. The "effective" focal length seems to be about 0.10" so the length of the arc you can engrave or cut is a function of the "effective" focal length and the diameter of the curved surface you want to engrave - or cut. You therefore must scale your computer graphic so it remains "in range". I did the following illustration to give you an idea of how much arc length you have to play with for diameters from 2 to 8".
One of the interesting capabilities of this laser "engraver" is the ability to do three dimensional "carving" - darker areas being cut deeper than lighter areas. This idea of using light and dark for "depth" has been around for a long time and there have been sevaral software programs that used it for creating virtual 3-D objects from gray-scale 2D images - Bryce 3-D being just one such program. The depth of focus of the laser beam limits the depth of the "relief" carving, but engravers have been doing some pretty amazing things -on coins - for a LONG time. Combine this low relief carving ability with the laser's ability to "pierce" and all kinds of possibilities open up.
So I got into a primitive CAD program to explore this "gray scale" relief laser carving idea. I created a shaded"basket weave" pattern in a primitive CAD program (it was last updated in 1993!) then took it over to Adobe PhotoShop to play with it, varying the size, rotating it, etc.. The BLACK areas will be completely pierced, the WHITE areas will remain untouched and the GRAY areas will be "engraved" to different depths based on each pixel's "blackness" or "whiteness" - lighter being ABOVE, darker being BEHIND".
Here are some variations using PhotoShops "Distort" filters - L to R - Unchanged, Ovalized, "spotlite" Lighting Effect and "zip-zagged".
This 3-D "printing" thing opens up new possibilities to "post lathe enhancments" to turnings.
Have a lot to learn about the laser "engraving", in this case with the Epilog Mini Helix, Will put up things as I find - and understand them.
