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glenn schramm
06-16-2012, 10:45 PM
I have an Epiplog helix 45w machine. I have been exploring gun stock checkering. I would like to no is the 4" focal lens the best lens to use? for longer focus length for convex and concave jobs like gun stocks. If so where is the best after market dealer of these lenses. Also if i was to change from the 2" lens that was standard with the machine.Do i need a spacer adabtor for this 4" lens and can i get those after market too.?

Craig Matheny
06-17-2012, 12:43 AM
I can not tell you about the gun stock but the lens buy it direct from Epilog their prices have come down and they sell the lens alone and then buy a focus gauge from them. Remember part of the way they pay for their great after market service is by profit on parts.

glenn schramm
06-17-2012, 1:05 AM
Thanks for the advice, but i have been quoted around $800.00 au for them through epilog, that is way to pricey.
I have an Epiplog helix 45w machine. I have been exploring gun stock checkering. I would like to no is the 4" focal lens the best lens to use? for longer focus length for convex and concave jobs like gun stocks. If so where is the best after market dealer of these lenses. Also if i was to change from the 2" lens that was standard with the machine.Do i need a spacer adabtor for this 4" lens and can i get those after market too.?

Mike Null
06-17-2012, 7:12 AM
I don't consider myself to be expert on this subject but on the several pieces I've done the 2" lens was quite adequate. If you try to make the image run from the top of the butt stock to the bottom then you will have focusing problems but leaving 3/4" or so margin at the top and bottom should enable you to engrave without problem.

Richard Rumancik
06-17-2012, 12:00 PM
It is certainly an issue of compromises - the 4" lens has greater depth of field but the image will look less crisp as the spot size will be quite large. If you try with a 2" lens, set your focus on the "average" distance to the part (not the peak) so it splits the difference.

Maybe since you are doing checkering and not a graphic you could get away with large spot size. But before you know it, someone will ask you to do a graphic image.

It might be worth doing some testing on scrap material - maybe you could bend some thin wood to simulate the expected curve and do some experiments. Or find some cheap wood item at the dollar store to experiment on.

One technique that has been used on curved items is to raster twice; once with the lower surface in focus and then raster again focusing on the higher point. But there is obviously a time penalty with two passes.

I just think that 4" is probably too much. If you need to change lenses maybe a 3" would do.

If you buy surplus lenses or Chinese lenses you will probably have to make your own mounts (or find a hobby machinist who can make one for you.)

John Noell
06-17-2012, 3:50 PM
I have been very happy with lenses sourced through laserresearch DOT net. They sell the 4" to fit a Helix for $165.

Rodne Gold
06-18-2012, 2:16 AM
I would also stick with the 2" lens and try to clock up (make level) the engraved piece.
We have bought expensive and cheap chinese 3" and 4" lenses and the spot size of either is too big to do any meaningful detailed engraving.