Owner`s manual

drawn race feature to the upper left. It‘s important to make all
measurements with regard to the desired center.
a. Draw a desired race-diameter circle (use a non-cutting
color) line for non-cutting) where you want the bearing
race to be.
b. Draw two additional race-diameter circles (solid lines),
one 0.015‖ to the left and one 0.015‖ to the right of the
original race circle. Group these two, and make them a
separate color from the other cuts. You now have two
circles, 0.03‖ apart in X. This partially corrects for the
beam‘s astigmatism.
c. Displace this two-circle group by 0.015‖ in the –X
direction and 0.010‖ in the -Y direction (displace toward
the upper left). This compensates for the misalignment of
the beam along the Z-axis when mis-focused (long) by
1.0‖. Do not scale or rotate the result! Use these same
displacements for all race sizes.
d. With the system out of focus (long) by 1.0‖ (use the Z button in the Focus mode),
vector-cut the two displaced circles at 100 percent power, 10 percent speed, and three
passes for Delrin, two for acrylic (The number of passes is variable, but this seems to
work for 3/32‖ -> 5/32‖ ball bearings obtained at Lowe‘s). For acrylic, make two
passes per side. This will be just deep enough for 3/32‖ ball bearings and a 0.022‖
polycarbonate bearing keeper.
e. Raise the table back to focus height, taking care not to crash the head, and cut the center
hole, the outer diameter, and anything else that needs to be cut or engraved. Make sure
the part cut out is last, or a small displacement error might result.
f. A bearing keeper can be cut out of thin (0.022‖) polycarbonate.
23. Snug Fit: For a tab-in-slot snug fit in ~0.2‖ acrylic, cut the slot 0.012‖ smaller than the
thickness of the acrylic.
24. Press fit for ¼-20 cap-screw head: Use a 0.179‖-radius (0.358‖-diameter) hole in acrylic.
Groove the screw head parallel to the screw shaft with the Dremel cutoff wheel or grinder. This
should help relieve the pressure and provide additional holding force to the plastic. Gently tap
the screw head into place, entering from the laser (larger-diameter) side. This is good for making
a fixed, screw-in acrylic knob.
25. Smooth, Wide Groove: A relatively smooth groove can be produced with equally spaced lines
cut out of focus. Cut as parallel vectors, 0.028‖ apart, 2‖ out of focus (long). Avoid cutting
adjacent lines sequentially to allow for cooling. Color adjacent vectors with sequential colors—
allow to cool between cuts for short grooves. You can use zero power cuts after regular cuts and
use multiple copies. P=7, S=10, 1000 PPI yields about 0.0143‖ of cut depth per copy.
26. Removing solder mask over copper from a printed circuit board: Engrave the area to be
removed at P=50, S=100, 500 PPI. Scrub off remaining film with acetone. Acetone won‘t touch
the un-lasered solder mask. Be careful not to engrave over any non-copper-filled areas, because
engraving directly on FR4 material will burn and turn it to conductive carbon.