Motor only moves in one direction

frans87

Hello,

I have problem with my printer set up :

One of the motors (extruder) moves well in one direction, but in the other direction the motor sounds bad and stays stuck. I swapped the wires with x axis, the problem is than the same on the x-motor and E-motor works ok, also changed stepper driver : same behaviour.

Inversing the wires inverses rotation as well as the direction problem.

I also tried without any load on the motor (no filament)

Vref : 0.45 V

I'm stuck just like this motor, could anybody help me ?

My config :
RAMPS 1.4
Repetier FW and Host
Arduino Mega
Cartesian printer (prusa i3)
Geared extruder

Thanks for your help,

Frans

frans87

UPDATE :

I can move the extruder motor just fine in both directions with the LCD command , even when extruder is cold !
In repetier host the same problem persists, so might be a problem between UI settings and FW ?

I tried to post configuration.h but it is to long for the forum...

Cheers,

Frans

frans87

Excuse me for the multiple posts, i've discovered something new :

In repetier host, the "bad" direction = retraction, is much faster than the extrusion speed. I can retract if i lower the feedrate setting to about 35, It doesn't work with the default feedrate of 100. When i move the motor from the LCD both retraction and extrusion speeds are the same and all is fluent.

Thanks for your interest,
Frans

Repetier

Ok, so it is only your max feedrate that is too high in firmware. Host has speeds stored in printer settings for fast and slow.

The ui in firmware uses other speeds. So reduce your extruders max feedrate to something retract can handle and adopt host settings to it.

frans87

OK, thanks for your answer.

So just to see if i understand well :

My settings in FW are :

Feedrate : 50
Start feedrate : 20
Accelleration : 5000

Nozzle : E3D-V6 0.4mm
ABS 3mm

Those were the default settings in the FW wich i didn't touch.

Now, if every thing's fine in manual control at 35 % feedrate, should i set Max Feedrate to 17.5 in FW ? isn't that very low ?
The difference between extusion and retraction seems very big, is this a fixed ratio ?
If my extruder doesn't work with the default values, could that mean that there's to much friction in the extruder ?
What are normal values for my extruder ?

Thanks again,

Frans

Repetier

Remember your true speeds are in eeprom, not exactly the one in configuration.h.

It takes force and time to melt filament so extrusion is slow. Retraction should be fast and there is much less force required (if the end is molten so you can pull back at all).

I would change speeds in host and see what works and what not. Then you know the maximum speed.

Speed depends on feeder and steps per mm and motor force you have. There are feeder that can do 100mm/s retraction and others have problems with 10mm/s. Most feeder should be able to handle 50mm/s. There is no fixed ratio. Most extruders can melt around 12mm³ which then gives the limit, retraction has no such restriction.

frans87

Thanks for your help, i'm printing right now !
I realised my extruder was not performing well. I made an other hobbed bolt my self and it extrudes well now.

I bought a kit, and i must say, i had to change a lot of things to make it a working machine.

The hobbed bolt i got with the kit, was made of theaded rod and i think the teeth were to coarse and sharp and because of the tread, not nicely centered. When the idler was adjusted too loose it scraped the filament and the tooth filed up with plastic, when tighted, it damaged the filament so it had to much friction in the extruder.

The hobbed bolt i made, has the the hobbed part in a plain shaft, has a finer thead, and is not as coarse, but it's a very hard bolt (from a volkswagen timing belt idler). It works very well now. I used this method : https://www.youtube.com/watch?feature=player_detailpage&v=gLP_OmY7iTY<br/><br/>Thanks for your help !

Frans