Prusa I3 Bad printing

[kapusta]

Which values I need to change to make step a little higher, this 600 to 900? or 3.3 to higher like 4?
#define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 4000,600} // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE {250, 250, 3.3, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {3000,3000,100,10000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
Thanks Alibert for reply!

[Alibert]

Measure before dabbling!

Either you have the source code for your current firmware, or you look it up via the settings you will find in the display controller. There will be an item which defines the steps/mm for the z-axis.

Now do the measurement with the calieprs as I posted before. When you go from z=0 to z=100 mm, the firware will move the stepper moter 100 times this steps/mm value. For example if the firmware thinks it is 100 steps/mm, it will move the stepper 100*100 =10000 steps to achieve the move.

So you now know how many steps were made by the firmware, and you have measured the actual movement in mm with the calipers. Now divide the (100mm*current_steps_mm, 100*100=10000 in this example) steps by this measured value and you have the actual steps/mm you need for the z-axis.

If you design and print a 150*150*1 mm square and print this you can do the same for the x- and y-axis axis by measuring

Be aware that in the source codes, there are multiple definitions for many printers. You will need to follow the logic for the defines starting from a file called configuration.h or similar.

[kapusta]

Hi guys, sorry for slow reply. yesterday I was calculating my steps for axis and got for E steps 112. It gives right amount of filament but it si realy slow, to slow. I don't know hot to fix that.

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,226} // default steps per unit for ultimaker //78.7402, 78.7402,1070,865.88
#define DEFAULT_MAX_FEEDRATE {500, 500, 1.2 ,50} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000}

Any thoughts?

[Alibert]

What do you mean with slow? The z-axis movement or the extrusion rate?

As to the first, that value of 1.2 may be adjusted a little upwards (it is the max speed of the z-axis in mm/s). Don't overdo it as the z-axis is the most problematic one in the i3 design and you will get artefacts or skipped steps if that setting is too high. The micro needs to generate 4000 pulses for the z-axis stepper to move the hotend 1 mm in z direction according to your defines. This means the stepper motor will need to do 5 whole revolutions (assuming a 200 step/revolution stepper). For the x- and y-directions, only 80 steps are needed per mm of movement.

According to those settings again, 226 steps are needed to push 1 mm of the filament through the nozzle, so if your true e-steps is 112, then change that 226 to 112.

PS: you might have already understood that those arrays in the defines specify the values for x, y, z and extruder motors in that order.

[kapusta]

I mean, extrusion rate is slow (E axis is slow).
My mistake, I did put 112 for E steps.
Z steps are not the problem right now (probably the next one), don't how can I speed up those E steps, or I'm on the wrong way understanding of my problem.
And one more thing, printer is jamming realy often since I changed to new filament. (Temperatures are good 185-195C, PLA-1.75, nozzle 0.4)
I'm using this firmware for my prusa mendel i3 -> https://github.com/KapustaB/3D-Prusa-Mendel-I3-Firmware
p.s.
Thanks for a good explanation on steps.

[Alibert]

Extrusion rate is determined by two things. The firmware settings will set the absolute maximum speed in mm/s that the gear will push the plastic filament through the nozzle. The slicer however determines at what speed it will request from the firmware when printing. You can't go too fast as the plastic will not have time to melt in the nozzle and the backpressure will exceed what the extruder gear can deliver in force.

[kapusta]

Thanks for clarify that to me. I will try something new today. I will reset all of settings in slicer/Cura.

You can't go too fast as the plastic will not have time to melt in the nozzle and the backpressure will exceed what the extruder gear can deliver in force.

Yes, I know that, but it was realy slow. I did get ok prints before.
Chears