## Print bed level calibration of Mini Kossel using M666

A is center of the print bed. B is tower X, C is tower Y, D is tower Z.

Manual calibration of print level makes the nozzle moving across one plane.

The calibration step is followed by.

Step 1: Set Z height at the center of bed. In this example, previous Z height was 215.70 mm where the nozzle touches the test paper whose thickness around 0.1 mm in middle of print bed. People use A4 or letter size print paper.  Use M114 to find current coordinate of the nozzle. The nozzle moved -1.65 mm below the Z height. So I increased the Z height by commensing  M666 H217.35.

New Z height = old Z height – difference

New Z height = 215.70 – (-1.65) = 217.35 mm

03/28/2015

Hopefully I gonna start printing object again within a day.

Three points base

I manually sanded the aluminium print bed, drilled three holes on the bottom side for precision level adjustment. When I inspected the top surface using a filler gauge whose minimum gap blade is 0.04 mm and a engineering square, I couldn’t find any high or lower spot that takes the blade.

However half hour of manual level calibration followed by G29 Auto level probe data showed about 0.2 mm level difference across the bed surface. I see there was huge improvement of print bed. At this point I’m skeptical about accuracy of the Auto level probe.

>>> M666 L
SENDING:M666 L
Current Delta geometry values:
P (Z-Probe Offset): X10.95 Y-4.30 Z-5.80
A (Tower A Position Correction): 0.00
B (Tower B Position Correction): 0.00
C (Tower C Position Correction): 0.00
I (Tower A Radius Correction): 0.00
J (Tower B Radius Correction): 0.00
K (Tower C Radius Correction): 0.00
D (Diagonal Rod Length): 214.86
H (Z-Height): 211.60

```20.00,60.00, -0.290 0.00,60.00, -0.270 -20.00, 60.00, -0.330 -40.00, 40.00, -0.150 -20.00, 40.00, -0.180 0.00, 40.00, -0.170 20.00, 40.00, -0.170 40.00, 40.00, 0.040 60.00, 20.00, 0.020 40.00, 20.00, -0.020 20.00, 20.00, -0.050 0.00, 20.00,-0.080 -20.00, 20.00, -0.140 -40.00, 20.00, -0.170 -60.00, 20.00, 0.150 -60.00, 0.00, 0.110 -40.00, 0.00, 0.060 -20.00, 0.00, -0.020 0.00, 0.00, -0.090 20.00, 0.00, -0.150 40.00, 0.00, -0.170 60.00, 0.00, 0.330 60.00, -20.00, 0.260 40.00, -20.00, 0.200 20.00, -20.00, 0.120 0.00, -20.00, 0.020 -20.00, -20.00, -0.050 -40.00, -20.00, -0.150 -60.00, -20.00, 0.300 -40.00, -40.00, 0.210 -20.00, -40.00, 0.150 0.00, -40.00, 0.040 20.00, -40.00, -0.070 40.00, -40.00, 0.260 20.00, -60.00, 0.260 0.00, -60.00, 0.210 -20.00, -60.00, 0.110 ```

``` 20.00,60.00, -0.260 0.00,60.00, -0.250 -20.00, 60.00, -0.280 -40.00, 40.00, -0.080 -20.00, 40.00, -0.090 0.00, 40.00, -0.120 20.00, 40.00, -0.140 40.00, 40.00, -0.160 60.00, 20.00, 0.090 40.00, 20.00, 0.070 20.00, 20.00, 0.020 0.00, 20.00,-0.020 -20.00, 20.00, -0.070 -40.00, 20.00, -0.130 -60.00, 20.00, -0.160 -60.00, 0.00, 0.200 -40.00, 0.00, 0.190 -20.00, 0.00, 0.100 0.00, 0.00, 0.020 20.00, 0.00, -0.050 40.00, 0.00, -0.120 60.00, 0.00, 0.150 60.00, -20.00, 0.210 40.00, -20.00, 0.140 20.00, -20.00, 0.120 0.00, -20.00, 0.050 -20.00, -20.00, -0.030 -40.00, -20.00, -0.070 -60.00, -20.00, 0.150 -40.00, -40.00, 0.180 -20.00, -40.00, 0.110 0.00, -40.00, 0.030 20.00, -40.00, -0.090 40.00, -40.00, 0.270 20.00, -60.00, 0.270 0.00, -60.00, 0.220 -20.00, -60.00, 0.130 ```

3/31/2015

The Auto calibration indeed worked out this time.
It turned out hard-to-find calibration bug was loose pulley of X axis’ stepper motor. The pulley supposedly secured by two M3 set scews but one set screw was barely holding it. The pulley was 5 mm to 10 mm off from the original position on the shaft.

```SENDING:M666 L Current Delta geometry values: X (Endstop Adj): -4.68 Y (Endstop Adj): -4.23 Z (Endstop Adj): -4.65 P (Z-Probe Offset): X10.95 Y-4.30 Z-5.80 A (Tower A Position Correction): 0.00 B (Tower B Position Correction): 0.00 C (Tower C Position Correction): 0.00 I (Tower A Radius Correction): 0.00 J (Tower B Radius Correction): 0.00 K (Tower C Radius Correction): 0.00 R (Delta Radius): 110.95 D (Diagonal Rod Length): 213.25 H (Z-Height): 207.05 >>> g30 A D213.25 SENDING:G30 A D213.25 Starting Auto Calibration.. Z-Tower Endstop Offsets -0.3500 X:-4.68 Y:-4.23 Z:-4.65 -0.2700 -0.3400 Tower Position Adjust -0.1800 A:0.00 B:0.00 C:0.00 0.0600 -0.5200 I:0.00 J:0.00 K:0.00 -0.1700 Delta Radius: 110.9500 X-Tower Y-Tower Diag Rod: 213.2500 Using diagional rod length: 213.25mm (will not be adjusted) Iteration: 1 Adjusting Endstops.. Z-Tower Endstop Offsets -0.0200 X:-4.62 Y:-4.73 Z:-4.98 -0.1100 0.1100 Tower Position Adjust 0.0500 A:0.00 B:0.00 C:0.00 0.0900 -0.0900 I:0.00 J:0.00 K:0.00 0.0100 Delta Radius: 110.9500 X-Tower Y-Tower Diag Rod: 213.2500 Iteration: 2 Adjusting Endstops.. Z-Tower Endstop Offsets 0.0100 X:-4.54 Y:-4.81 Z:-5.00 -0.1400 0.1300 Tower Position Adjust 0.0600 A:0.00 B:0.00 C:0.00 0.0100 -0.0500 I:0.00 J:0.00 K:0.00 -0.0000 Delta Radius: 110.9500 X-Tower Y-Tower Diag Rod: 213.2500 Iteration: 3 Adjusting Endstops.. Z-Tower Endstop Offsets -0.0300 X:-4.53 Y:-4.86 Z:-4.99 -0.1800 0.1600 Tower Position Adjust 0.0400 A:0.00 B:0.00 C:0.00 -0.0000 -0.0100 I:0.00 J:0.00 K:0.00 0.0100 Delta Radius: 110.9500 X-Tower Y-Tower Diag Rod: 213.2500 Iteration: 4 Adjusting Endstops.. Z-Tower Endstop Offsets 0.0100 X:-4.53 Y:-4.87 Z:-5.02 -0.1500 0.2000 Tower Position Adjust 0.0500 A:0.00 B:0.00 C:0.00 -0.0100 0.0100 I:0.00 J:0.00 K:0.00 0.0100 Delta Radius: 110.9500 X-Tower Y-Tower Diag Rod: 213.2500 Iteration: 5 Endstops: OK Adjusting Delta Geometry.. Adjusting Delta Radius (110.95 -> 109.95) Z-Tower Endstop Offsets -0.2800 X:-4.53 Y:-4.87 Z:-5.02 -0.3700 -0.1800 Tower Position Adjust -0.5400 A:0.00 B:0.00 C:0.00 -0.2700 -0.3900 I:0.00 J:0.00 K:0.00 -0.3300 Delta Radius: 109.9500 X-Tower Y-Tower Diag Rod: 213.2500 equalAB=false equalBC=false equalCA=false c: -0.54 x: -0.27 y: -0.39 z: -0.28 ox: -0.18 oy: -0.37 oz: -0.33 radius:109.9500 diagrod:213.2500 Radius Adj Complete: No DiagRod Adj Complete: Yes RadiusA Error: -0.09 (adjust: 0.00) RadiusB Error: -0.02 (adjust: 0.00) RadiusC Error: 0.05 (adjust: 0.00) DeltaAlphaA: -0.04 DeltaAlphaB: -0.15 DeltaAlphaC: 0.19 Adjusting Delta Radius (109.95 -> 110.45) Z-Tower Endstop Offsets -0.1300 X:-4.53 Y:-4.87 Z:-5.02 -0.1700 -0.1200 Tower Position Adjust -0.2300 A:0.04 B:0.15 C:-0.19 -0.1100 -0.2300 I:0.00 J:0.00 K:0.00 -0.1500 Delta Radius: 110.4500 X-Tower Y-Tower Diag Rod: 213.2500 equalAB=false equalBC=false Tower CA Equal (C=0.02 A=0.01) TowerB Radius error - adjusting adj_RadiusB set to 0.50 c: -0.23 x: -0.11 y: -0.23 z: -0.13 ox: -0.12 oy: -0.17 oz: -0.15 radius:110.4500 diagrod:213.2500 Radius Adj Complete: No DiagRod Adj Complete: Yes RadiusA Error: 0.01 (adjust: 0.00) RadiusB Error: -0.06 (adjust: 0.50) RadiusC Error: 0.02 (adjust: 0.00) DeltaAlphaA: -0.02 DeltaAlphaB: -0.03 DeltaAlphaC: 0.05 Adjusting Delta Radius (110.45 -> 110.95) Z-Tower Endstop Offsets 0.0300 X:-4.53 Y:-4.87 Z:-5.02 -0.1400 0.1400 Tower Position Adjust 0.1400 A:0.06 B:0.18 C:-0.24 0.0300 0.0800 I:0.00 J:0.50 K:0.00 0.1400 Delta Radius: 110.9500 X-Tower Y-Tower Diag Rod: 213.2500 equalAB=false equalBC=false Tower CA Equal (C=-0.11 A=-0.11) TowerB Radius error - adjusting c: 0.14 x: 0.03 y: 0.08 z: 0.03 ox: 0.14 oy: -0.14 oz: 0.14 radius:110.9500 diagrod:213.2500 Radius Adj Complete: No DiagRod Adj Complete: Yes RadiusA Error: -0.11 (adjust: 0.00) RadiusB Error: 0.22 (adjust: -0.25) RadiusC Error: -0.11 (adjust: 0.00) DeltaAlphaA: -0.28 Adjusting Delta Radius (110.95 -> 110.70) Z-Tower Endstop Offsets 0.0200 X:-4.53 Y:-4.87 Z:-5.02 0.0800 -0.0700 Tower Position Adjust -0.0300 A:0.34 B:0.18 C:-0.52 0.0100 -0.0900 I:0.00 J:0.25 K:0.00 -0.0700 Delta Radius: 110.7000 X-Tower Y-Tower Diag Rod: 213.2500 equalAB=false equalBC=false Tower CA Equal (C=0.09 A=0.08) TowerB Radius error - adjusting c: -0.03 x: 0.01 y: -0.09 z: 0.02 ox: -0.07 oy: 0.08 oz: -0.07 radius:110.7000 diagrod:213.2500 Radius Adj Complete: Yes DiagRod Adj Complete: Yes RadiusA Error: 0.08 (adjust: 0.00) RadiusB Error: -0.17 (adjust: 0.12) RadiusC Error: 0.09 (adjust: 0.00) DeltaAlphaA: 0.15 DeltaAlphaB: 0.00 DeltaAlphaC: -0.15 Z-Tower Endstop Offsets 0.2000 X:-4.53 Y:-4.87 Z:-5.02 0.2900 0.0200 Tower Position Adjust 0.1400 A:0.34 B:0.18 C:-0.52 0.2000 -0.0600 I:0.00 J:0.25 K:0.00 0.0300 Delta Radius: 110.7000 X-Tower Y-Tower Diag Rod: 213.2500 Iteration: 6 Adjusting Endstops.. Z-Tower Endstop Offsets 0.0200 X:-4.34 Y:-4.93 Z:-4.83 0.0900 -0.0400 Tower Position Adjust 0.0100 A:0.34 B:0.18 C:-0.52 0.0200 -0.0400 I:0.00 J:0.25 K:0.00 -0.0400 Delta Radius: 110.7000 X-Tower Y-Tower Diag Rod: 213.2500 Iteration: 7 Adjusting Endstops.. Z-Tower Endstop Offsets 0.0100 X:-4.32 Y:-4.96 Z:-4.81 0.0700 -0.0400 Tower Position Adjust 0.0100 A:0.34 B:0.18 C:-0.52 0.0200 -0.0200 I:0.00 J:0.25 K:0.00 -0.0400 Delta Radius: 110.7000 X-Tower Y-Tower Diag Rod: 213.2500 Auto Calibration Complete Issue M500 Command to save calibration settings to EPROM (if enabled) >>> M500 SENDING:M500 echo:Settings Stored SENDING:M666 L Current Delta geometry values: X (Endstop Adj): -4.32 Y (Endstop Adj): -4.96 Z (Endstop Adj): -4.81 P (Z-Probe Offset): X10.95 Y-4.30 Z-5.80 A (Tower A Position Correction): 0.34 B (Tower B Position Correction): 0.18 C (Tower C Position Correction): -0.52 I (Tower A Radius Correction): 0.00 J (Tower B Radius Correction): 0.25 K (Tower C Radius Correction): 0.00 R (Delta Radius): 110.70 D (Diagonal Rod Length): 213.25 H (Z-Height): 207.05 >>> g29 SENDING:G29 0.020 0.020 0.020 0.030 0.020 0.020 0.020 0.050 0.050 0.030 0.020 0.020 -0.010 -0.010 0.100 0.070 0.050 0.020 -0.010 -0.020 -0.040 0.080 0.050 0.030 0.000 -0.010 -0.030 -0.050 0.060 0.020 0.000 -0.020 -0.030 -0.030 -0.050 -0.020 -0.020 -0.040 -0.030 -0.010 -0.010 -0.010 -0.050 -0.050 -0.050 -0.030 0.020 0.020 0.020```

``` ```

```>>> g30 x-20 y-60 SENDING:G30 X-20 Y-60 Bed Z-Height at X:-20.00 Y:-60.00 = -0.0500 Carriage Positions: [208.98, 176.90, 135.24] ```

```20.00,60.00, 0.020 0.00,60.00, 0.010 -20.00, 60.00, -0.000 -40.00, 40.00, 0.040 -20.00, 40.00, 0.030 0.00, 40.00, 0.020 20.00, 40.00, 0.020 40.00, 40.00, -0.010 60.00, 20.00, -0.040 40.00, 20.00, -0.020 20.00, 20.00, -0.010 0.00, 20.00, 0.020 -20.00, 20.00, 0.050 -40.00, 20.00, 0.070 -60.00, 20.00,0.100 -60.00, 0.00, 0.100 -40.00, 0.00, 0.060 -20.00, 0.00, 0.030 0.00, 0.00, -0.000 20.00, 0.00, -0.020 40.00, 0.00, -0.030 60.00, 0.00,-0.050 60.00, -20.00, -0.050 40.00, -20.00, -0.030 20.00, -20.00, -0.030 0.00, -20.00, -0.020 -20.00, -20.00, 0.010 -40.00, -20.00, 0.030 -60.00, -20.00,0.080 -40.00, -40.00, -0.010 -20.00, -40.00, -0.030 0.00, -40.00, -0.030 20.00, -40.00, -0.010 40.00, -40.00, -0.000 20.00, -60.00, 0.020 0.00, -60.00, -0.030 -20.00, -60.00, -0.050 ```