3D Printing & Modeling + Ed3DP

1. Educator 3DP Manual

1.6. Printer Bed Calibration

Educator 3DP- Printer Bed Calibration Procedure

The Educator 3DP automatically adjusts or "compensates" the printing level of the actual print bed using a stored map of the bed contours.  This compensation grid is generated in step 3 below- calibrate bed.  It works by going to a known point and then taking a grid of bed heights at different x & Y points using the inductance sensor which is then stored as a type of grid contour height map.  The inductance sensor should be manually set at 2mm above the tip of the extrusion nozzle (if its too low then it will hit your 3D prints or if too high then the extrusion nozzle will smash into the bed while it attempts to lower to take height readings with the inductance sensor.  Once done, this should provide perfect printing directly onto the aluminium bed.  This only needs to be done infrequently or when the nozzle is changed etc.  There are four steps to get the printer bed calibrated (compensated).

1.       Level the X-axis:

a.       Turn on the printer and “home all”

b.       Use the “move” menu and jog the extruder head down till it is just above the bed on the LHS about x=20mm

c.       Using a piece of copy paper jog the nozzle down “Z-“ in 0.1mm increments until there is light pressure on the paper- this is about 0.2mm between the bed and nozzle i.e. thickness of the paper

d.       Move the nozzle to the RHS to about x=180mm

e.       Adjust the RHS Z-axis drive stepper (large vertical threaded rod) either clockwise or anticlockwise as needed to get the same height and pressure with the paper

f.        Repeat this process to check that he x-axis is level across the bed

2.       Set the “Z0” height (z zero):

a.       Turn on the printer and “home all”

b.       Goto the “more” menu on the touch screen- the buttons are basically in order of use from top LHS

c.       Press “Goto Z0”- the printer will home first and then go its currently set Z zero point i.e. where the nozzle is just above the bed for printing

d.       Using a small piece of copy paper use the “Z up” and “Z down” keys to “jog” (move) until there is firm pressure on the paper from the nozzle

e.       Press “Set Z0”

f.        Press “Home XYZ axes”

g.       After the printer has homed and stopped press “Save ALL Settings” and reboot printer

h.       Repeat the process and check correct Z0 i.e. firm pressure with copy paper from the nozzle

3.       Calibrate Bed Level:

a.       Complete this step immediately after step 2 above

b.       In the “more” menu press the “Calibrate BED Level”- the printer will “probe” a grid of 11 x 11 points using the inductance sensor

c.       Press “Save ALL Settings” to permanently keep new values and reboot printer

d.       Repeat the Z0 height setting procedure from step 2 above and double check- reboot between checks i.e. power off.

4.       Fine tune Z0 with test print:

a.       Setting the nozzle height for Z0 i.e. the bed as in step 2 above is a good approximation however due to differences between people’s perception of “firm” pressure and variances of paper thickness and errors like waste filament under the nozzle giving a false result it is wise to do a test print.

b.       Create a plain rectangular prism about 100 x 100 x 1mm in your 3D modelling software or use this Bed Plate Test GRid STL model

c.       In the “Slicer” i.e. Cura etc turn off raft and all other support and set the “Platform Adhesion Type” to “none" and creat your gcode or use Bed Plate Test Grid GCode for 3DP.

d.       Pre-heat and prepare the printer- both extruder and bed

e.       Perform the test print (you only need a few lines) and examine the resultant first layer shape and characteristics as follows:

                i.      The ideal result is the first layer will lay down like flat pasta-  even thickness and well adhered to bed (touch it with your fingers once printer is stopped)

                ii.      If the filament lays down like rice paper i.e. very thin or there are bubbles or excess filament pushed outwards then the nozzle Z0 is too low- move it up 0.1mm as in step 2 and repeat

                 iii.      If the filament lays down like a cylindrical sausage without being “capped off” and pushed into the bed a bit then the Z0 is too high-lower it 0.1mm and try again