Last edited: Furst (08/26/20)
Eye injuries can result from flying chips or broken bits. Cuts can occur from contacting sharp tools or broken glass. Burns can result from hot cutting tools or parts. Serious injury can result from pinching or entanglement in moving parts. Poor housekeeping creates tripping and cutting hazards for other users. Do not leave machine running unattended. Eye protection, closed toe shoes, long pants, and protective clothing must be worn when using this machine to prevent injury. Long hair must be tied back and jewelry must be removed before operating this machine to prevent entanglement.
The Sherline CNC is used exclusively for for drilling holes in glass, ceramic, silicon, and other brittle materials. Milling of brittle materials is not supported. The Sherline uses a high speed spindle in combination with abrasive diamond drill bits to slowly abrade the material away.
Typical applications include adding macro to micro interface connecters to Microfluidics chips.
The Sherline CNC uses a retrofit Sherline mini mill in combination with the FlashCut CNC software. This SOP does not cover dxf2fgc conversion code.
FlashCut CNC offers a user interface for positioning, zeroing, and running the G-code, however it has no CAM capabilities. This means that G-code must be hand written based on the location of holes.
A backing plate is required for drilling, and should be bonded to the substrate to be drilled to improve backside cut quality and prevent drilling into the fixture. If bonding is not permitted, slowing down cut speed may result in less blowout on the backside of the hole and a backing plate should still be used.
The machine is now zeroed in X and Y
The machine is now zeroed in X, Y, Z
The sample G-code is as follows:
G21 (select mm units) G49 G80 G90 (cancel offsets, cancel cycles, absolute coordinates) G98 (Move the drill away from the part when drilling is finished)
G00 X0 Y0 Z5 (rapid move to the upper left corner of slide, 5mm above)
(Hole drilling blocks)
(G73=canned peck drilling cycle 1) G73 X17 Y-12.5 z-1.2 Q.1 R0.5 F2.5 (x=coordinate of hole, y=coordinate of hole, Z=depth of hole, R=retract value, Q=depth of each peck, F=feedrate)
(G73=canned peck drilling cycle 2) G73 X58 Y-12.5 z-1.2 Q.1 R0.5 F2 (x=coordinate of hole, y=coordinate of hole, Z=depth of hole, R=retract value, Q=depth of each peck, F=feedrate)
(Closing block) M30
When using G73 canned cycle, X and Y set the coordinates of the hole, and Z sets the maximum depth below machine zero. R sets the starting height of the drilling cycle as well as the retract height between pecks) (Q sets the depth each peck will go into the workpiece until it excedes the Z value set above. F sets the feedrate or the rate at which the drill will decend into the workpiece) (If you are cracking the slide or getting excessive break out you should reduce the feedrate value and the depth of each peck.
The Z value should be slightly deeper than the thickness of the sample without backing plate. This insures all holes drilled in the sample are through holes. NEVER drill without a backing plate as you will hit the fixture.