Hone In New CNC
by smithtodd24
Engineering Journey Overview
Follow this step-by-step engineering journey to see real progress updates, challenges overcome, and practical experience.
Progress Updates (11 total)
Update #1: Hone In New CNC
Want to build consistent at home pcbs with clean traces and no cleanups
Challenges faced in the past:
-Dealing with non level tables/boards
-Vice needed to raise part for drill operation tends to bend board.
-Isolation cut to thin causing solder to bridge
-Pads not separating from each other due to program settings+tool diam
Challenges Overcome: Built CNC, honed in initial parameters for small board
Update #2: CNC Built
10% completeFinalized Assembly
Update #3: Setting a Z-Map
15% completeFound out how to use the Z-probe feature. This feature allows you to create a contour map for where the tool touches the board. This creates a dynamic zero in the z-axis which was a crucial step for surfaces that aren’t level.
Update #4: Created V1
20% completeCreated V1 board, didn’t like pad size/separation amount between the trace and the remaining copper
Update #5: V2 Board
20% completeFound the good parameters
Looking Back: Found the good parameters:
Zmap Params:
-16 zero points (4x4)
-2”max Z height
—.10” min Z height
-cut depth : -.0018”
-pass depth: -.0006”
-spindle speed : 900
-Tool diam: .005”
-Number of isolation paths: 3 (Increased distance between trace/remaining copper)
Update #6: Solder Complete
30% completeCompleted Solder
Challenges Overcome: Solder complete without any cleanup needed to prevent shorts
Update #7: Relays/Wiring
40% completeRelays complete
Update #8: Finalized Setup
40% completeAdded Connectors/Designed enclosure and 3D printed the enclosure
Update #9: Final Test
75% completeNot shown in this goal was previous testing to validate continuity, state changes, and temp rise of the system before reaching Steady state.
This testing was to validate all state changes with full assembly, validate fast switching time, and to validate thermals in an enclosed box
Update #10: Moving to large board (Failure)
75% completeAs a final benchmark of honing in the CNC, a large boards was attempted. During this cut it was impossible to fully cut the traces and isolate them from the pcb. Double the typical depth was attempted and still no luck.
Obstacles Faced: Could not fully isolate the traces at absurd cut depths. Something was going on as the height map seemed to not be working.
Looking Back: Looking at the setup closely I observed some bow/spring in the board and the mdf it was mounted too. Small pressure would adjust where the board stabilized. The height map doesn’t apply a lot of pressure and stops right when contact was detected. A cut actually does apply pressure. I theorize that this compliance is causing the issue
Update #11: Large Board Success
100% completeFinal success after changing the setup to have the board secured to the platform with double sided tape
Challenges Overcome: Large board, cut and drilled no issues.
Looking Back: Working small board params:
Setup:
Pcb clamped to mdf. On metal clamp contacting
board for z probe
Z probe:
6x6 matrix with 60x60 interp. 1.7 max, -.7
min (safe), 7 feed, ran at 120% Feedrate (FR)
Mill:
Went to .004” diam, 3 isos @ 40 % overlap, .
.0024 total cut, .0008/pass, FR 3.5
Drill:
.085 cut, FR 3.7
Working big board params:
Setup:
Switched to pcb double sided taped to the mdf
and that held to the 3d print platform. 2 black
clamps on the right, one on the left, metal
clamp used in back left for z probe
Z probe:
10x10 matrix with 60x60 interp. 1.7 max, -.7
min (safe), 7 feed, ran at 120% Feedrate (FR)
Mill:
Went to .004” diam, 3 isos @ 40 % overlap, .
.0024 total cut, .0008/pass, FR 3.5
Drill:
.085 cut, FR 3.7