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Bed levelling issues

Posted by Falcon3333 
Bed levelling issues
May 25, 2017 06:35AM
I've managed to figure out loading the filament
Now just struggling to bed level on tronXY p802ma
Too close no extrusion and with aslight adjustment it extrudes but pla lifts from build plate
I have blue tape on heat bed
Re: Bed levelling issues
May 25, 2017 07:44AM
Also filament extrudes as extruder heats up even before it gets to print start position
Re: Bed levelling issues
June 07, 2017 09:53PM
Filament always drizzles out, it is just a fact of life that we have learned to live with.
1st you will need a pair of tweezers it remove the dangling filament just before it starts to print.

Bed leveling is an art, and before you learn how, you will crash the head into the bed several times, have your off switch in your hands until you get proficient.
The first step is to slowly raise the z-axis using the LCD controls until you come close to the top cross bar, disable the steppers and adjust the z-axis stepper screw leads until both side are level with the bar. then lower the z-axis the same way.

Now for the hard part. the best way to level the hotbed is to auto home, lower the z-axis to the lowest point (+- .1 or .2) making sure that a thin piece of paper will slide under the nozzle.
this require a lot of patients and skill as every time you adjust the Z-Axis senor/end stop it will shift more than .2mm, the distance required to allow filament proper adhesion.

Now disable the steppers manually move the head to several points across the bed adjusting the 4 bed leveling thumbscrews until all points are as close as possible and you can slide the paper under the nozzle.

This is where it gets complicated, and you need to have a z-axis thumbscrew to adjust the proximity sensor by micro mm so when you auto home it will always return to the same height.
without this thumbscrew you will work constantly trying to keep the bed in level. I was pulling my hair out because of the Bed leveling problems. Every-time my printer burped would crashed into the bed I was white knuckled pulling the plug.
3D Printed Power supply case and switch was the first real project.

When you get it to print and you do not have an adjustable Z-Axis sensor holder find a STL file and Print one , this will save you a lot of stress.
The first real valuable 3D Printed object Printed On my printer was A Proximity senor adjustable sensor holder. Found one on thingiverse and modified it with ThinkerCad.com online Free 3D Printer Cad software.

Sample adjustable Sensor

Need more help message me.

Edited 2 time(s). Last edit at 06/07/2017 10:18PM by Roberts_Clif.
Re: Bed levelling issues
June 08, 2017 02:24AM
The adjustable sensor is way to complicated.
The bed must be level for sure, so follow the instructions above. Then you home the printer with the nozzle say 1mm above the bed.
In the startcode of the slicer you have a line G92 Z1.0 which tells the printer the actual nozzle height. ( after G28 )
Now you can play with that value until you found a setting that keeps the filament from curling and the first layers do not get squished to much.

Remember: when you raise the G92 Z value, the nozzle goes closer to the bed.
Re: Bed levelling issues
June 09, 2017 12:48AM
Most Z endstop designs on kits simply suck, which causes the builders of these kits to want "auto leveling".
IMHO there is an easier way.
I use this design for a Z endstop:

But I take it a step further - on the home position of my bed I don't use a spring, rather I use a solid spacer and use a long nylon nut attached to the M3 bolt for the adjustment.
So when I need to adjust the bed height in relation to the nozzle i pre-heat the bed/nozzle, bring the x and y close to their home positions, then home the z-axis. If the paper sides under too loose I adjust the long nylon nut slightly and re-home the z-axis, or if it's too tight, same thing - simple and fast.
It's hard to explain but these pictures from my Instructable show what I do.

The Instructable is here:

I also use hex bolts and mylocks on the other 3 bed corners, the ones with springs. That way I can use a hex driver to adjust them if necessary without using downward force on the bolt and not having to use thumb screws, pliers etc and the nylocks will hold unlike wing nuts commonly found on the kits.

My updated Instructable on our Prusa i3 Build
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