Bltouch tuning - adjusting distance from trigger point to nozzle
-
I'm finishing tuning my DIY 3d printer (its a corexy based on BLV's design) with 3 independent z axis. I want to be able to do automatic bed leveling with the BLtouch.
When I designed the BLtouch mounting I read the BLtouch manual and found the tip of the probe should be between 2.3 and 4.3mm over the nozzle so I designed it for 3mm as a nice round value.
I have been doing the calibration procedure and ended up with a height difference of 2.8mm, so I put that on my G31 command of config.g
When I test the full bed levelling procedure, always en up with the following message:
Error: Some computed corrections exceed configured limit of 0.50mm: -5.000 -5.000 -5.000
Reading the troubleshooting guide I found the following:
The bottom of the BLTouch plastic shell must be 8mm+-0.5mm away from the nozzle tip to trigger properly.
Which actually accounts exactly for the -5mm that the previous error gives... but I'm a bit reluctant to change the mounting height before checking with someone else... the bltouch manual seems quite clear and if I raise it by 5mm I don't know if it will actually trigger.
I also don't want to raise the maximum correction sice it seems a bit excessive to have it at more than 5mm.
Also, since the whole procedure is working fine, maybe it is just something that I'm missing in my configuration files...
my z-probe section of config.g
; Z-Probe M950 S0 C"io7.out" ; create servo pin 0 for BLTouch M558 P9 C"^io7.in" H5 R0.2 F100 T6000 ; set Z probe type to bltouch and the dive height + speeds G31 P500 X0 Y20 Z2.800 ; set Z probe trigger value, offset and trigger heightmy bed.g
G28 ; home G30 P0 X15 Y20 Z-99999 ; probe near a leadscrew G30 P1 X150 Y290 Z-99999 ; probe near a leadscrew G30 P2 X285 Y20 Z-99999 S3 ; probe near a leadscrew and calibrate 3 motorsDo I need to raise the probe by 5mm? or can I compensate for it in the configuration since the whole process seems to work except for the actual compensation?
-
So does the probe, as mounted, meet the 8mm +/- 0.5mm requirement?
Is it trigger correctly?
Moving to Z=0 does the tip of the nozzle just touch (or almost touch) the bed?
If you change the limit from 0.5mm (that's very small - mine is 3.0mm) does it work?
Frederick
-
Thanks for the reply!
So does the probe, as mounted, meet the 8mm +/- 0.5mm requirement?
No. If I understood that sentence, this is from the tip of the probe when its retracted to the nozzle tip, right? in that case I have about 3mm, which is what the BLTouch manual asks for:
So I don't know where the 8mm comes from or if that depends on the BLTouch version. This is why I wanted to ask about it
Is it trigger correctly?
Yes, it triggers. During my initial testing I saw error messages of not triggering, but after I adgusted the bed height closer to the probe, it does trigger correctly
Moving to Z=0 does the tip of the nozzle just touch (or almost touch) the bed?
Yes, I first of all adjusted manually the bed with a piece of paper, so I have about 50um of clearance between nozzle and bed
If you change the limit from 0.5mm (that's very small - mine is 3.0mm) does it work?
I just tried and with 6mm as the limit it does, if that's OK I can leave it like that, but it seems strange that it gives me -5mm in all three points but when I do single point probing I can get 0.0mm as Z height wightous issue
Leadscrew adjustments made: -5.000 -5.000 -5.000, points used 3, (mean, deviation) before (-5.000, 0.000) after (0.000, 0.000)
So... with 6mm it seems to work, it is that to me it seemed too much and I don't know exactly where the 5mm difference comes from
-
Glad to hear it is working.
Do you home the Z axis with the probe or Z endstops?
Do you home before running the bed leveling?
Thanks.
-
I actually have both, I have endstops at the max Z and the probe at min Z.
Yes, I do a homing before the bed leveling, I suppose the firmware doesn't allow otherwise.
I'm still testing things and if possible trying to do a first print today, I think I will only use the Z probe if it works well.
-
@ballanux said in Bltouch tuning - adjusting distance from trigger point to nozzle:
So I don't know where the 8mm comes from or if that depends on the BLTouch version. This is why I wanted to ask about it
Yes it seems to vary for the version. Best to follow the manual for your version.
-
@phaedrux Thanks for the confirmation, it confused me quite a bit.
By the way, I'm doing my first test print now and while I still have some things to adjust I'm quite glad how everything is working
-
the upto date documentation has all been changed (even on some of the older pdf's) I have documentation downloaded from antclabs here that shows that distance as being
8mm +/- 0.2mm
