Engraving On a Contoured Surface

[Jeff Watkins]

Hi James, you know I haven't tested the outer limits of it. I have done >2in logos/lettering on a couple tumblers. I used the Project Mark to keep it from stretching the sides out. When I did my tumbler test I ran a .25in by 3.5in wide hatch to see where the engraving stopped. I figured that I could comfortably do a little over 2in wide logo on a 30oz tumbler.

For your Derby Cover I would form a piece of foil over it and then use a sharpie to black it out. Try a low power and high speed pass and see what the extents of your lens is. Maybe try focused on the center then drop it a little so the center is still clearing along with the edges of your logo. You'll get to a point that focus is too low and the center will start suffering.

[Kev Williams]

nothing like real world testing
fiber dof.jpg
this was simple enough-
The lines are 6.1" long, about the max for my 150 lens. This is just a simple ramp test, and not only does it show the- I'll call it "usable depth of field", it's a great way to find your dead-on focus point...

I shimmed the right side of the plate right at the edge of the lines, the left side is flat on the table.
top lines are shimmed 3/8", middle are 1/4", bottom are 1/8".
I focused as close as I could to the actual plate center.
I did a cross hatch at 45 and 135 degrees, .08mm spacing-
the top of each pair was run at 100% power,
the bottom of each pair was run at 40% power
speed 1500, freq 35.

While there IS quite a bit of focusing leeway- I was surprised the 1/4" version engraved edge to edge at 100 power- the low power lines show that, even with only an 1/8" rise, there's substantial power loss at the far edges. Since I focused in the middle, this means the drastic losses begin at less than .060" from the prime focus point, which isn't a whole lot of free play...