Nozzle height problem

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rvb89
Posts: 2
Joined: Wed Nov 30, 2016 9:04 am
Location: France

Nozzle height problem

Post by rvb89 » Thu Dec 08, 2016 10:13 am

Hello,

I'm having a problem with my new i3 Pro B when I want to print.
The printing starts too high.

I do the auto home then with a sheet of paper I adjust the bed but when I start to print the level is around 2-3mm too high and the screen shows Z:0.3
At this time the only way I found to print is to start the printing, pause it and adjust the bed but in auto home the nozzle ends slightly under the level of the glass

I already did the following checks:
-Z endstop is working
-both sides of the axis are moving at the same level
-if I move Z-axis of 10mm the Z-axis moves of the right distance
-I noticed some hard points in the movements of the Z-Axis so I put them in a M8 die to remove imperfections then added lube, now it moves smoothly.
-I noticed between 2 auto home procedure there was always a difference of the same distance, sometime the axis was going up without releasing the endstop then slighly going lower and stopping.
after searching on the web I had to change in Configuration_adv.h

Code: Select all

#define X_HOME_RETRACT_MM 5
#define Y_HOME_RETRACT_MM 5
#define Z_HOME_RETRACT_[b]MM 2[/b]
to

Code: Select all

#define X_HOME_RETRACT_MM 5
#define Y_HOME_RETRACT_MM 5
#define Z_HOME_RETRACT_[b]MM 4[/b]
2mm for the auto home fine tuning were not enough to release the endstop so the auto home was false.
Now it moves enough to do the normal procedure and the auto home is always at the same height.
I solved this problem with the software but maybe there's something wrong as the stock firmware was made to work with 2mm?
(I'm planning to use auto bed leveling... when I'll be able to print a sensor holder)

For my nozzle height problem,
I'm mainly using Cura but I also tried with Slic3r with a configuration file from the forum but the problem remains the same, I also tried printing from Octopi or directly the SD.

here are the start codes the softwares use:

Cura

Code: Select all

G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G1 Z15.0 F9000 ;move the platform down 15mm
G92 E0 ;zero the extruded length
G1 F200 E3 ;extrude 3mm of feed stock
G92 E0 ;zero the extruded length again
G1 F9000
;Put printing message on LCD screen
M117 Printing...

Slic3r

Code: Select all

G28 ; home all axes
G1 Z10 F5000 ; lift nozzle
Now I don't know what else I should try to fix this problem.
Is there anything to configure in the firmware or is it a hardware issue ?

The printer is using the latest firmware available from the forum.

Thanks.
Printer: i3 Pro B

3dtech
Posts: 46
Joined: Mon Apr 04, 2016 8:42 pm
Location: MONA TILES COMPOUND, NR. CHHANI CIRCLE, CHHANI ROAD, VADODARA - 390002. GUJARAT, INDIA.
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Re: Nozzle height problem

Post by 3dtech » Wed Feb 08, 2017 1:10 pm

Assuming that we are concerned with the XT PLUS I have to say that the problem with that suggestion is that there is then a gap between the end of the feeder tube and the nozzle piece. This then causes molten filament to find its' way up through the screw connection and ooze out on top of the heater block... a mess! That has been my experience. The two heatsink/feeder assemblies have been assembled and their overall lengths compared to within a few hundredths of a millimetre and yet when fixed in place will still exhibit a measurable height discrepancy. There is a slight amount of play in the slot that the assemblies mount into, maybe a shim applied here would help. And bear in mind that the very action of tightening the locking screw could cause a bit of vertical movement.
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