CNC Bed level issues &weird gcode (cnc code) issues - important when using small bits

Snapmaker 2.0
1

Very happy with my A350 so far and am a very experienced 3D printing / CNC hobbyist with Aerospace background. Very familiar with duet Wifi, Gocde, firmware customisation, CURA and Python scripting.

But… i am struggling with the CNC element and appreciate that its still Alpha. There are a few little issues with the Luban interface but the two major issues for me are:

  1. Manual or Auto Bed Levelling feature is really needed for small mill bits e.g. 1mm flat mills to avoid digging in and snapping :frowning: . I looked at this post from the original snapmaker (Bed leveling for pcb milling?) and tried it. Defined a load of points using M421 IJQ notation. But adding an M420 S1 to enable bed levelling in the .cnc file causes the CNC head to travel up by 6.15mm and mills in thin air-- guess better than crashing into the bed. Interestingly the 6.15 seems to be the same Z amount as reported when you you run M420 S1 from the console.

  2. If CNC gcode is saved to a file it seems to have a number of G0 Z moves in at the beginning (see below in bold) which again cause it to mill in mid air. But if the G code is generated in Luban and loaded into the workspace and executed it doesn’t do the G0 Z moves and mills as you would expect!!

Any info on fixes or improvements on the CNC would be great… or if i can help beta test im game.

;Header Start
;header_type: cnc
;renderMethod: line
;file_total_lines: 5472
;estimated_time(s): 127.22020983794516
;max_x(mm): 21.12
;max_y(mm): 4
;max_z(mm): 0
;min_x(mm): -21.12
;min_y(mm): -4.23
;min_z(mm): 0
;work_speed(mm/minute): 600
;jog_speed(mm/minute): 3000
;power(%): 0
;Header End

G0 Z10.00 F120
G0 Z0.50 F120
M3 P100
G0 Z0.20 F100
G0 Z0.20 F3000
G0 X-17.45 Y0.29
G1 Z-0.20 F600

Any info on fixes or improvements on the CNC would be great… or if i can help beta test im game.

2 Likes
2

on your number 1, I completely agree, some form bed leveling is DEFINATLY required. I actually cut out a 3/4" chunk of High density Ply and CNC’d it to the Bed measurements then milled it “flat to the machine” to figure out how much it was out after having to do a job about a half mm deeper than i wanted to just to carve the whole image.

2mm out over 12"!!!
flat|375x500

1 Like
3

I might look at this again as i think i can solve the issue i was having with milling in thin air. and its possibly because i had set the z washout to be over the 1st mm. On one of my other posts about 10x10 mesh levelling i ened up putting am M206 Z offset in firware to counteract this utill @brent113 pointed out putting a z washout factor in (snapmaker default is mesh correction over whole model ) causes this weird behaviour.

So possibly with what i know now doing a bed mesh level as per my recent post and enabling it (without Z washout being defined via M420 Z0)might get the bed levelling working with the CNC