- The setup instructions only discuss calibrating the Z-axis in the X plane
- There is no provision for adjusting the Z-axis in the Y plane
- The provided wasteboard is not 100% square to the X and Y machine axes, plus the wasteboard was not entirely parallel to the Z-plane
Consequences (why you should correct this:
1 and 2) No matter how well you calibrate the Z-axis to the X plane, your machine is relying on all the assembly parts to provide a true Y-plane calibration “out of the box”. This will never happen since there are too many variables. (slop in connecting the slide rail to the endplates, manufacturing tolerance issues, etc.). In my case the calibration was off by a significant amount.
=> Your end product simply won’t be accurate to your input file. Fine if you are doing artsy v-carving, but for precise pieces, it’s a non-starter
=> No matter your best feeds and speeds, you will easily break small end mills. The deeper you mill, the more likely this will be to occur.
3) If you are always cutting away from fresh stock in the x and y axes, this isn’t an issue, however, if you want to A) Remill a piece, and you use the printed guides for setup or B) Only mill a side of a piece, your work will be off (ever so slightly
Fortunately, the fix is almost trivially simple.
A) Drill and tap 2 holes (TOTAL) directly between the centerline of the holes on the X-Carriage used to mount the Z-axis rail. I used #8, but whatever works for you - whatever tap and machine screws you have around.
B) Assemble everything per the instructions fully, attempting to get the Z-axis as close as you can in the X plane. Tighten everything down
C) Using some scrap MDF or Plywood (~ 12" by 12" to give yourself some working room to calibrate in the next steps, perform a facing operation on the entire workpiece (just be careful of the clamps!!)
- Get a precision 1" 1/4" shank. I got a Whiteside 6210 CNC Spoilboard Surfacing Router Bit, 1/4" Shank
- I used Fusion 360 with the following settings:
- 1000 mm/min feedrate (ALL) except for 200 mm/min plunge feedrate. Works great, no burning. Spindle speed MINIMUM (16k RPM)
- Bottom height -0.5mm (this is the amount of material to remove in the facing)
- Single pass
- Pass direction 0 degrees. Stepover 25mm. This will visually highlight the amount of calibration you’ll need to do.
- No lead in or lead out, straight line transition.
- Run it. If you Z-axis is calibrated perfectly, the MDF should look like as smooth as a factory surface, in which case, you are lucky and skip to step K below.
D) If your test run looks like you can put it up on your house for siding (which mine did) It’s time to calibrate. LEAVE it clamped to the spoil board.
E) If you have them installed, completely remove the dust arm brackets. You don’t want to measure against these at all.
F) Take this opportunity to tighten the v-wheels on the Z axis. Grind down an old 3mm Allen key so you can get it in the lower bolts
F) Loosen up the z-axis rail “tight enough” that it stays on, but loose enough you can adjust it.
G) Using a machinist’s square AND YOUR wonky 12"x12" test piece as the reference plane, first align the Z-axis with the y-plane (going to use the new holes you tapped.) MAKE ALL YOUR CALIBRATIONS against the spindle carriage. If the top of the spindle carriage is leaning toward you (mine was a LOT) insert a machine screw in the LOWER hole you tapped (if the carriage is leaning away, use the top hole, and do everything in reverse). In my case, slightly tighten the top 2 bolts so the carriage doesn’t fall down and turn your machine screw in until the spindle carriage is perfectly perpendicular. GENTLY tighten the mounting screws on either side of your machine screw.
H) Now slightly loosen to top screws again and align the Z-axis with the X-plane, per the default instructions. Use a rubber mallet to SOFTLY tap the carriage. Tighten all 4 screws and continue to check for perpendicular in both axes as you do so. Once all 4 screws are properly tight, do a final check. Repeat the process until perfectly perpendicular in both directions. DONE.
I) Reinstall the dust shoe rails, etc.
J) Re-run your facing operation on your scrap, remembering to take off more material. If your z-axis is calibrated correctly, it will now be flat.
K) Now its time to take your calibrated machine and face the spoil board.
L) Use all the same settings as step C above, EXCEPT:
- Sketch/Stock size 750mm (X), 760mm (Y)
- Pass Direction 90 degrees
- Stepover 22mm
- From other side
M) Your spoil board should have been “factory parallel” enough that 0.5mm faced the entire surface. If not, run again a tad lower. NOTE: If your spoil board still looks like crap, with ridges or “ocean waves” repeat the calibration procedure, but this time, you don’t need your test piece, you can calibrate directly against the spoil board, since it’s been machined.
N) There should now be a nice ridge on the left and right sides of the board that you can use to align your workpieces to the TRUE machine Y-Axis and setup/clamp down your parts with a machinist’s square against this ridge.
This is my first post, so hopefully, I’ll be able to add pictures as a follow-up.