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First Layer Too High

Posted by ElmoC 
First Layer Too High
April 02, 2017 01:07PM
I am trying to get my delta configured and I cannot get the nozzle positioned correctly for the first layer. It is always too high. No matter what values I change, it seems it is always the same. I have adusted the homed height in the M665 command and the probe triggered point in the G31 command. I am using G32 before printing and running 1.17c. What am I missing?
Re: First Layer Too High
April 02, 2017 01:12PM
If you are running G32 before your print and the first layer is printing too high, then your trigger height (G31 Z parameter) is set too low.

Make sure that the G31 command in your config.g file comes after the M558 command that sets the probe type, not before it.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: First Layer Too High
April 02, 2017 01:16PM
Quote
dc42
If you are running G32 before your print and the first layer is printing too high, then your trigger height (G31 Z parameter) is set too low.

Make sure that the G31 command in your config.g file comes after the M558 command that sets the probe type, not before it.

G31 is right after the M558. To be clear, if the G31 Z parameter is set too low, to get the nozzle closer to the build plate, increase the Z value? (Pretty sure that's what it means but just wanting to be 100% on it)
Re: First Layer Too High
April 02, 2017 02:00PM
After borrowing some feeler gauges, I was able to get the height set. What bothered/worried me was I had gone through the probe trigger height calibration to get the value I had. (Nozzle just gripping paper, G92 Z0, raise Z, G30 S-1). The actual value I had to use was 1mm higher. So while the probe said it was at 1.32mm when triggered, the G31 value I ended up with as 2.4. Is this typical or is my printer's operator just really screwed up?
Re: First Layer Too High
April 02, 2017 02:32PM
No, that doesn't sound right. Is your printer a Delta, Cartesian, or CoreXY? If it isn't a delta, are you using 5-point bed compensation?



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: First Layer Too High
April 02, 2017 02:34PM
It is a delta and using 6 factor/16 point probing in the bed.g file.

; Auto calibration routine for delta printers
; Before running this, you should have set up your zprobe Z offset to suit your build, in the G31 
; command in config.g.

M561			; clear any bed transform, otherwise homing may be at the wrong height
G31 X0 Y0		; don't want any probe offset for this
G28			; Home the printer

M98 Pdeployprobe.g	; Deploy the probe
G30 P0 X0 Y0 Z-99999	; Dummy probe.  Just to be safe.  Probably not needed with the inductive probe.

; bed.g file for RepRapFirmware, generated by Escher3D calculator
; 16 points, 6 factors, probing radius: 90, probe offset (0, 0)
G30 P0  X0.00   Y90.00  Z-99999
G30 P1  X45.00  Y77.94  Z-99999
G30 P2  X77.94  Y45.00  Z-99999
G30 P3  X90.00  Y0.00   Z-99999
G30 P4  X77.94  Y-45.00 Z-99999
G30 P5  X45.00  Y-77.94 Z-99999
G30 P6  X0.00   Y-90.00 Z-99999
G30 P7  X-45.00 Y-77.94 Z-99999
G30 P8  X-77.94 Y-45.00 Z-99999
G30 P9  X-90.00 Y-0.00  Z-99999
G30 P10 X-77.94 Y45.00  Z-99999
G30 P11 X-45.00 Y77.94  Z-99999
G30 P12 X0.00   Y45.00  Z-99999
G30 P13 X38.97  Y-22.50 Z-99999
G30 P14 X-38.97 Y-22.50 Z-99999
G30 P15 X0  Y0  Z-99999 S6

M98 Pretractprobe.g	; Retract the probe.

G1 X0 Y0 Z250 F15000	; get the head out of the way of the bed

Re: First Layer Too High
April 03, 2017 05:54AM
Do you measure the G31 Z value with the printer running hot, or cold?
With some designs you can have quite a serious amount of thermal 'expansion', which will lead to the same results... my printer has something around 0.3mm difference...
Both the bed and the Hotend should be at the operating temperatures during the calibration...
Re: First Layer Too High
April 03, 2017 07:44AM
I think I found the source of the problem. This BLTouch I have is a piece of crap. It seems to jam and misread a lot. I have removed it from the printer and it is not residing in the trash can. I'll be replacing the one on my other printer soon.
Re: First Layer Too High
April 06, 2017 10:47AM
Quote
ElmoC
I think I found the source of the problem. This BLTouch I have is a piece of crap. It seems to jam and misread a lot. I have removed it from the printer and it is not residing in the trash can. I'll be replacing the one on my other printer soon.

That's actually nice to know. I had been looking at them, but decided against it because it was using some sort of mechanical device to probe with the whole servo control lines. Since it is a mechanical device, I imagined it would be something that requires some sort of lubrication and maintenance.
Re: First Layer Too High
April 06, 2017 06:03PM
There were a lot of them in use at the Midwest RepRap Festival and the people I talked to spoke highly of them. I have one on a Tevo Little Monster I just got and it seems to do a fine job. The pin does need to have freedom of movement though, so keeping it clean and possibly lubed will help it (I think).
Re: First Layer Too High
April 06, 2017 06:27PM
Quote
WZ9V
There were a lot of them in use at the Midwest RepRap Festival and the people I talked to spoke highly of them. I have one on a Tevo Little Monster I just got and it seems to do a fine job. The pin does need to have freedom of movement though, so keeping it clean and possibly lubed will help it (I think).

Yeah. Tried that. 10 minutes later it is jamming. Support was no help. Ask me to send a video of the probe having problems and when I did, they just ignored the problem and told me to clean it. Did that before and it didn't fix it. Why do you think it will this time? The pin was going up, but it wasn't sending the signal.
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