Scanning Z Probe giving erratic Z values

Phaedrux

@j-pickens I think the two options were included because it's still an early device and it wasn't clear which would work better in different cases so both were included for the user to test.

droftarts

@j-pickens From @T3P3Tony

In theory the 12mm coils are higher resolution than the 15mm coils but we need more testing to confirm which is best so we provide both

I'm converting my TronXY X5S to something a bit better, and currently setting it up as a test machine, with which I can easily swap toolboards (I have 3x 1LC of different versions, Roto and SZP, as well as a few Mellow/Fly toolboards from @jay_s_uk) and coils. I'm planning on testing all the SZP setups and updating the documentation, hopefully next week.

Ian

j.pickens

@droftarts That's funny, I have the same Tronxy X5S. Bought it for the 400mm cubic print area, the core XY, and the unique steel rod rails on aluminum extrusion axes. I never set it up with the stock extruder and electronics. Chucked them in the bin and installed a Duet 2 board, Paneldue, and E3D Hemera Revo. Added a BL Touch style Z probe and off I went. The Duet automated bed tramming made all the difference. Can't wait to set up the new Z axis probe on my Toolchanger.

droftarts

@j-pickens Ah, that sounds like a X5SA-400 PRO! Mine is the entry level X5S (not even an A), so I don't have the steel rods, just plastic wheels running in the extrusion, and mine has a 330mm square bed. But I got it for free, just over 3 years ago! The previous owner didn't know how to route the belts, or build the hot end, and never got it working properly. I also put a Duet 2 WiFi and BL Touch on it, and it worked okay, but I was never that happy with it, so it has sat in the corner being used as shelving for a long time.

I took it apart last week, rebuilt the frame properly with button head bolts in the blind joints, and replaced a bunch of bearings that were very sticky, fitted a 6HC and replaced nearly all the wiring to the X carriage with a CAN cable. Now it runs much better. It doesn't have an extruder or hot end at the moment, as it's about to do SZP testing.

Eventually it will get an upgrade to either VzBot or Voron Trident top end, but for now the CoreXY layout is sufficient. It's the weak and flimsy 12V bed that's getting ditched first, after the SZP testing, for something like a RatRig V-core kinematic setup.

Ian

travasky

Any update from anyone on this front? Ive just been running the machine without the probing which is less than ideal. @dc42, Is there anything you can add to help us out here?

droftarts

@travasky I have been doing some testing, and will update the instructions tomorrow, and reply here with some other observations.

Spoiler: I don’t see erratic readings, though I’ve been testing using a Roto toolboard rather than the SZP toolboard.

Ian

Phaedrux

@travasky said in Scanning Z Probe giving erratic Z values:

Any update from anyone on this front? Ive just been running the machine without the probing which is less than ideal. @dc42, Is there anything you can add to help us out here?

Please send an email to warranty@duet3d.com and CC your reseller. Include a link to this forum thread and the details of your original purchase. You'll receive a reply with a form to fill out.

kgbengt

@Phaedrux said in Scanning Z Probe giving erratic Z values:

@travasky said in Scanning Z Probe giving erratic Z values:

Any update from anyone on this front? Ive just been running the machine without the probing which is less than ideal. @dc42, Is there anything you can add to help us out here?

Please send an email to warranty@duet3d.com and CC your reseller. Include a link to this forum thread and the details of your original purchase. You'll receive a reply with a form to fill out.

Hi!

I have what seems to be the exact same problem with erratic readings from the scanner, Hardware fault?

droftarts

@kgbengt When you get erratic readings, do you mean the probe reading reported in DWC moves around (say, +/-5), or that you get sporadic 999999 readings?
Please report what size coil you are using (12mm or 15mm), and the response to M558.1 K# and M558.2 K#, where # is the probe number.

I've been doing some testing recently (still ongoing sorry for the slow update). The setup is quite sensitive; I can configure it to produce sporadic 999999 readings by setting the drive current to 16 rather than 15 on the 12mm coil.

A few notes on mounting:

In theory the 12mm coils are higher resolution than the 15mm coils but we need more testing to confirm which is best so we provide both (in progress: very generally, I find it easier to get sporadic 999999 readings with the 12mm coil)
Make sure there is no metal in the 30mm ABOVE the coil, or it will pick this up and give false readings
Mount the coil 1-2mm above the nozzle.
Route the SZP ribbon cable away from the coil, ie make sure it doesn't go over the coil
Ensure that the ribbon cable is FULLY inserted into the tiny connector, at both ends. Try reseating this if you continue to get erratic readings
I use M2.5 countersunk screws (often supplied with smaller fans) to mount the coil, which stick out about 0.7mm. M3 countersunk screws stick out a bit further. There are M3 screws with low profile heads, usually between 0.8mm and 1mm; search for "m3 ultra low profile thin head".

Configuration and calibration is a little vague in the instructions, but mostly correct (I've just added that reading offset needs to be set in config.g as well as drive current); I have some notes on that, but need to check and verify them. Briefly:

My coil is mounted 2mm above the nozzle, I have G31 Z2 set, so it is 4mm above the bed when it triggers.
The part that needs testing is the height to calibrate the drive current. I tend to do this at the same height as G31 is set, ie Z2. The instructions aren't very clear on this at the moment.
drive current AND reading offset should be set with, for example, M558.2 K1 S15 R101133 (use the numbers you get from the drive current calibration)
Note that the current instructions tell you to check for 'sensible readings' (ie not 999999 when far from the bed) BEFORE reading vs height (M558.1) calibration. I've found I can get sporadic 999999 AFTER this calibration, but only when further (ie Z5 and higher) from the bed. I'm trying to narrow down the factors that cause this, but it seems to be setting the drive current too high.
reading vs height calibration is pretty much as in the instructions.

Let me know if that helps.

Ian

trulm

Hi, I had the very similar problems with the SZP, but I fixed it with your instructions in this thread.

Now I can use the SZP to do a 3-point bed leveling, but when I start the G29 or G32, all points of the mesh are on 0.0mm deviation.

Do you have any tips on what the problem might be, or have you ever had a similar case?

I use the 12mm coil.

; machine_zprobe.g

; 2024-08-21

; Z-Scanning Probe for T0
M558 K1 P11 C"120.i2c.ldc1612" H5 F6000 T6000			; configure scanning probe t0 via slot #1
M308 A"SZP coil" S10 Y"thermistor" P"120.temp2"			; thermistor on SZP coil
G31 P9400 X32 Y0 Z1.7 K1					; set t0 Z probe trigger value, offset and trigger height, Z4 means 4mm offset Probe to Nozzle
M558.2 K1 S15 R139620						; set drive current and reading offset

; Z-Scanning Probe for T1
;M558 K2 P11 C"121.i2c.ldc1612" H5 F6000 T6000			; configure scanning probe t1 via slot #2
;G31 P500 X0 Y0 Z0.7 						; set Z probe trigger value, offset and trigger height

; Mesh Bed Compensation
M557 X-180:180 Y-180:180 S18					; define grid for mesh bed compensation

; bed.g

;  2024-08-21

; Heat bed and nozzle
;M140 S60 							; set the bed to 60C
M104 T0 S220 						        ; set the t0 to 220C

; prepare printer
G1 Z2 F800
;M190 S60 							; wait for the bed to reach 60C
M109 T0 S220							; wait for the nozzle to read 220C
M98 P"Bedleveling.g"						; start 3-point-Leveling

; Clear any bed transform
G29 S2 								; Does the same as M561!

; mesh bed compensation
M557 X-175:175 Y-175:175 S20:20					; define grid for mesh bed compensation
G29 K1 S0 							; Probe the bed, save height map to "heightmap.csv" and enable mesh bed compensation

; Bedleveling.g
; Bedleveling with 3 Points

; 2024-08-20

; Z-leveling with 3 points and scanning probe after Z-homing
G28								; home all axes
while true
	G30 P0 X-180 Y-180 Z-99999 K1				; probe point 0 near Z1-joint
	G30 P1 X0 Y180 Z-99999	K1				; probe point 1 near Z2-joint
	G30 P2 X180 Y-180 Z-99999 S3 K1				; probe point 2 near Z3-joint and calibrate all Z-motors
	if abs(move.calibration.initial.deviation) < 0.01 || iterations >3
		break

; move to startposition
G1 Y0 Z50 F1000
G28 XU

; _3_Mesh_Bed.g

; 2024-08-12

M291 P"Do you want to Mesh Your Bed?" S3
M291 R"PREPARING BED COMPENSATION (MESHING)" P"Now homing and heating up (nozzle & bed). Wait for further instructions." S0

; preparing
G28
;M140 S60 															; Start heating bed to 60c
;M190 S60															; wait for Bed temperature
G10 P0 S200 														; turn on t0

;Beep 3 times
M300 S600 P250
G4 P401
M300 S600 P250
G4 P401
M300 S600 P250
G4 P401

M291 R"NOTICE" P"Bed Mesh Starting." S2
G32 																; Executes the bed mesh procedure defined in bed.g

; place t0 and bed
G1 Z20 F800			 												; raise bed
G1 X0 Y0 F4000	 													; center t0

;Beep 3 times
M300 S1500 P200
G4 P250
M300 S1000 P200
G4 P250
M300 S500 P200
G4 P250

G1 Z100 F800 														; Move the bed to Z 100mm from the nozzle so that there is room to retract the z probe if desired.
G1 X0 Y0 F4000 														; Move the bed to Z 100mm from the nozzle so that there is room to retract the z probe if desired.
M291 R"NOTICE" P"Do you want to turn off your heaters (Bed & Nozzle)?" S3

M140 S0																; turn off heated bed
G10 P0 S0 															; turn off t0

Phaedrux

@trulm said in Scanning Z Probe giving erratic Z values:

but when I start the G29 or G32, all points of the mesh are on 0.0mm deviation.

Can you explain more what you mean by this?