Having a hard time starting out [Prusa i3] e3D v6 hotend, pla clogging all the time

Question

So I've assembled my first 3D printer out of mostly spare parts and bits.. Got everything setup, at first i used a all metal hotend from china, E3D v6 replica's for 10$ The beginning of the test cube, 3 different attempts, learning about the settings.. In each case, i stopped the printer early because it was not moving high enough Z axis, meaning it ended up, grinding around inside the previous layer. Unfortunally it constantly failed, sometimes in the beginning, sometimes mid print. It failed by clogging up, I thought i'd better get a "decent" hotend, so I puchased a E3D V6 hotend 0.4mm nozzle. and set it all as a bowden setup. Still fails. This is how my printer looks most of the time, me cleaning out clogging. My main issues 1) Hotend clogging up, "way up in the cold part" as if it's retracting melted plastic upwards. Result, nozzle + entire insides of the hotend is clogged up, I'm fairly quick now to remove the clogging, but it does not really help me out. 2) Z-axis is not raising enough. It' appears 1st layer is printet "into" the glass, meaning 1st layer is invisible, then second layer is barely visible. My Z-axis is connected via 5mm rods, (M5) to 2x nema 17, 1.8(200) steppers. and used the prusa calculator via google and set the step to 75.. not sure about the 0.8/0.8*1 in the firmware so i left it.. Things I tryed allready, - Calibrating PID temperature for the hotend. - Calibrating / leveling the bed to the hotend, allowing only 1 single sheet of paper to fit under it at anylocation at Z-home - Printing pla with to high temperatures, not a good idea what a mess. I'm not sure weither it's my Marlin setup, my G-code or whats up, but I'm kinda frustrated right now This is my typical slic3r settings(hope you can see, not sure about the resolution on the webpage) And promterface.. (havent really done anything here, except when i was calibrating the hotend temp for marlin.) Attached files - Marlin for Ramps 1.4 - 20mmx20mmx20mm test cube Any help would be appriciated... 
 Attachments: Marlin.zip 20mm_cube.g.zip

bwelsby · Answer

Hi Martin, First things first lets try and sort the Z axis, the E3D clogging may be partly due to the Z axis not lifting enough causing too much back pressure on the extruder. How you got 75 is confusing so lets start from scratch. Your stepper motor requires 200 full steps for one rotation, however it is usual to have your stepper drivers configured for micro stepping and it is common to have this set to 16 times. Check what your stepper drivers are and what links have you on your RAMPS for this. So lets assume that this is the case, the stepper motor will require 200 x 16 micro steps for one full revolution thats 3200 A standard M5 rod has a pitch of 0.8 mm so 3200 steps will move the z axis by 0.8mm Therefore to move the z axis by 1mm you require 3200/0.8 * 1 steps = 4000 What I see in your firmware is: 
 #define DEFAULT_AXIS_STEPS_PER_UNIT {100, 100, (75.0*8/0.8)*1, 800} 
 (75.0 *8 / 0.8) * 1 = 750 Try this 
 #define DEFAULT_AXIS_STEPS_PER_UNIT {100, 100, 4000, 800} 
 Use pronterface to raise the z axis by say 10mm and measure to confirm.

bwelsby · Answer

If you are using 1.75mm filament the bowden tube should fit into the hot end as far as it can up to the heat break there shouldn't be any room for the filament to curl up. See E3D instructions E3D-v6 Assembly - E3D-Online Calibrating the extruder steps per mm: Disconnect the bowden from the drive end and mark a point on the filament at the drive exit. Tell extruder to extrude 100mm and mark at same exit point. measure length between the two points, it should be 100mm. Adjust the extruder steps per mm to correct. New value = (100 / measured length) * old value In your config you have it currently set to 800 new value would therefore be (100 / measured length ) * 800