Hello All,
And many thanks in advance for any help you can provide on this topic as I'm fairly new at 3d printing.
So let me give you some details about the configuration of the printer I've assembled:
-Electronics: Ramps 1.4 + Arduino Mega 2560 running Marlin 1.0.2
-Motors: 5x 17HS840 stepper motors (they hold a max operating current of 1.8A)
-Motor drivers: DRV8825 configured at 1/32 micro stepping.
-Hotend: Single, E3D v6 1.75 mm (initially on direct extrusion and now bowden mount (yes there's the issue)
-Nozzle 0.4mm / for 1.75mm filament
-Not sure what other relevant information i can give you but if I'm missing something please let me know.
Now, at the beginning it was working like a charm, i was able to print on nice quality and didn't have any problems at all except for the speed i could print at. if i set the speed higher than 20 mm/s I had bad quality. Sometimes even steps loosing, which i fixed by measuring and calibrating all axis motors. nevertheless i noticed that sometimes if i raised the speed i had less quality and some times i had some clogging. which i fixed by dissasembing the whole hot end and cleaning part by part with lindustrial thinner (toluene+acetone+alchol...).
So.. after a few of those I decided to print the parts needed and go fo the bowden configuration, as many people says that gies you more precision and better prints by eliminating much of the inertia of the extruder (mainly because you remove the motor weight).
so as i was removing the old extruder i also printed parts for adding couple of cooling fans for PLA ( i had noticed that i strongly needed them) and a support for adding an autolevel sensor (yes now i know it's stupid to change so manuy variables at once, oh well).
So after mounting everything and calibrating the new extruder steps/mm (to 300) i found that i have several problems of under extrusion. i'm not sure if under extrusion or over extrusion it is, but the fact is that at some point the filament starts having problems to be extruded and the printings are all messed up. First the motor starts "clacking" (yes many of you know that sound) and looks like it was missing steps.
I've been trying with changing variables for a few days:
- Increasing/decreasing temperature (tried several, from 185 to 250°C)
- Slowing/speeding print speed,
- reviewed the calculations on my calibration many times
- increased the current to the motor to the point that it actually heats more than I wished (this actually helped a bit not not enough to fix, the problems just delays more in appearing)
- increased the pressure to the filament till it gets deeply marked (and damaged)
- reducing the flow(%) in Cura in steps of 5% from 100% to 85% (not fixed but when got to 85% the extrusion was not even enough for a good print.. still the same clacking and under extrusion eventually appeared)
-cleaning the nozzle with the so called atomic method (does not fix it)
- In cura printing at any speed 10 / 20 / 30 / 40 / 50 or 60 mm/s won't fix the issue.
I've noticed that the first layers are printer perfectly... it is when it start doing the infill (maybe cause it's going faster) that it blocks the nozzle
In fact if I stop the printing when it is blocked or jammed or whatever it is what happens, i have to remove the filament manually cut the tip and immediately reinsert pushing manually, I can make the filament melt and pass thru the nozzle with no effort.
Just some extra information attached, my Configuration.h and my Cura's profile are attachede. Here are some of my speed config settings on the Configuration.h file:
#define DEFAULT_AXIS_STEPS_PER_UNIT {200,200,8000,300} // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE {300, 300, 3, 45} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {3000,3000,100,10000}
#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 3000 // E acceleration in mm/s^2 for retracts
#define DEFAULT_TRAVEL_ACCELERATION 3000 // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
#define DEFAULT_XYJERK 20.0 // (mm/sec)
#define DEFAULT_ZJERK 0.4 // (mm/sec)
#define DEFAULT_EJERK 5.0 // (mm/sec)
Do you think i'm having too small torque because of the micro stepping? i really do not know what else to try 
I apologize if I wrote too much information but I guess that could save time on the question/answer back and forth for details... Also apologize for the looooooong thread but please believe me.. i'm truly desperate now!
thanks a lot for your help and time!
Gabe