defective RAMPS?

Hi,

I do have a problem with a stuttering stepper motor on my E axis (extruder): I use a Arduino Mega 2560 with Ramps 1.4 on it and the latest Marlin firmware.
Changing the current on the potentiometer of the stepper driver dies not give any better results.

The symtoms are:
# VERY hot heatsink on the stepper during operation
# stuttering stepper no matter which potentiometer setting
# absolutely no power on my (geared!) stepper: can hold it easy with a plier

Therefore I did the following:
# checked the voltage from an old stepper I used about a year ago (Wade Extruder, 2,8 V; 1,68A) and the voltage of the stepper I'm using since months (geared with 17HS19-1684S-PG5 2,8 Volt, 1,68A) -> same therefore ok
# tried different Pololus (Sainsmart A4988 and Pololu md09b) -> nothing changed
# switched the Arduino 2560 and changed it to an Sainsmart -> nothing changed
# tested the extruder stepper on the X axis port -> works perfect!

I was able to print several parts perfect with my new geared metal extruder, but the stepper startet stuttering after a while - now it's not even possible to extrude even a mm - therefore I assume my Ramps Board is defect on my extruder 1 port - or does anybody have a better idea?

Edited 1 time(s). Last edit at 10/03/2014 06:12PM by RepRapper_Austria.

Have you tried it on the 2nd extruder port on the Ramps board?

---

_______________________________________
Waitaki 3D Printer

Possibly the wire has fractured either inside the stepper or along its path inside the insulation, and when you plugged into the X socket, you inadvertantly remade the connection

Also seperate motor wires from endstop wires if they run along together, in case of interference

Two things to eliminate before condeming the RAMPs

Quote
Mutley3D
Possibly the wire has fractured either inside the stepper or along its path inside the insulation, and when you plugged into the X socket, you inadvertantly remade the connection

Unfortunatel not - also a second Nema 17 Stepper had shown the same problem therefore I assume it's not the cable

Quote
Mutley3D
Also seperate motor wires from endstop wires if they run along together, in case of interference

The wires do run free without contact to another stepper cable or endstop cables.

Quote
waitaki
Have you tried it on the 2nd extruder port on the Ramps board?

Not yet - but definitely will do the test - hope I do not need a second temperature sensore because of the min/max temperature which is set in the firmware...

Quote
waitaki
Have you tried it on the 2nd extruder port on the Ramps board?

Yes, with no difference.
I assume that after reducing acceleration a LOT and do print much slower now, the Bulldog has too less force to push a 3mm PLA filament through a 0,4mm hole:
My wade had a ratio of 47 / 11 = 4,3 the stepper I'm using now on the Bulldog has 5,2 but a larger diameter on its "hobbed bolt" which causes the problem.

Will try to mount a stepper with 1/17 or 1:19 which I also have in my workshop...

#####
EDIT: Mounted a 1:19 stepper and so far it works great: this configuration has so much power that i can groove the filament when extruding at 300mm/min and the Pololu doesn't even get warm...

Edited 1 time(s). Last edit at 10/17/2014 02:48PM by RepRapper_Austria.