Nozzle height
September 23, 2016 04:22AM
According to the instructions, the nozzle should rest about 4mm above the bed. Mine doesn't as it stop on the bed and attempts to print from this position.

How can I adjust the nozzle height?


Re: Nozzle height
September 23, 2016 06:01AM
The process I use every time I turn on the printer is to Home All and then do at least one Auto Bed Compensation.

The Auto Bed Compensation runs the bed.g macro and should probe your bed which will allow the printer to calibrate where 0mm in height is. Most people on here have updated the default bed.g to do 6 factor (or place) calibration, Here's my fishers bed.g as an example:

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
; Probe the bed and do 6-factor auto calibration
G30 P0 X-65 Y-37.5 Z-99999 F14000; X tower
G1X0Y0 F10000
G30 P1 X-52 Y30 Z-99999 ; between X and Y towers
G1X0Y0 F10000
G30 P2 X0 Y75 Z-99999 ; Y tower
G1X0Y0 F10000
G30 P3 X52 Y30 Z-99999 ; between Y and Z towers
G1X0Y0 F10000
G30 P4 X65 Y-37.5 Z-99999 ; Z tower
G1X0Y0 F10000
G30 P5 X0 Y-60 Z-99999 ; between Z and X towers
G30 P6 X-32.5 Y-18.75 Z-99999 ; half way to X tower
G30 P7 X0 Y37.5 Z-99999 ; half way to Y tower
G30 P8 X32.5 Y-18.75 Z-99999 ; half way to Z tower
G30 P9 X0 Y0 Z-99999 S6 ; centre, and auto-calibrate 6 factors
G1 X0 Y0 Z100 F15000 ; get the head out of the way of the bed

When it completes the calibration by touching 6 places around the bed it will move the head up 100mm to give space for applying hairspray or any other bed things you might want to do. When the calibration completes you should see a message bubble in the web interface that shows the deviation, a low number like 0.04 is fairly reasonable, if you find this number varies a lot when you run it you may find that the homing is not being very repeatable - those micro switches and cable ties are not the best/most rigid.

If you find that the starting deviation is a large number then you'll need to adjust the total height of the printer in config.g - in this case the H param sets the height.

M665 R81.54 L160.0 B75 H150

The other adjustment that you may need to make is in config.g , near the end is a line -
G31 X0 Y0 Z-0.1 P200 ; Set the zprobe height and threshold (put your own values here)

This is trying to tell the printer the offset of height when the probe switch breaks contact - by the time the bed switch breaks contact (or at least reads 200 - visible on the machine control screen when probing) the Z height should be a negative number and this offsets that. In my case I upgraded the bed springs to stiffer springs so I need -0.2 to get a good start height. But only doing some test prints will tell you if this is right, set to low the extruder will probably skip and set to high and it will not stick.

If it's not too late I would recommend that you don't apply the buildtak yet, just use some painters tape (I found the 3m green to be much better than blue) and then whilst you tune these settings you won't run the risk of wrecking the buildtak. I have made a number of upgrades to my Fisher but by far the best was to change to a glass build plate. Initially, I got the local glass company to cut me a 2mm float glass (needs to be float to be flat) disc and I used double sided carpet tape to attach it to the supplied plate. Since then I have added a heated bed and this needs at least 4mm float glass to withstand the temperature.


DC42 Kossel 330mm x 2meters
My Thingiverse Creations
Re: Nozzle height
September 24, 2016 02:50AM
Hi Dadiy,

Thanks for the useful info for the future.


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