Stepper Motor Ramps Control

Our first printer has had more than its fair shair of problems but I dare say we are really close to being full-go. Two problems we are still having that I am hoping you all may help us with. The first is that the stepper motor on the etruder starts to skip and stop turnng the large gear wheel around 15% into the print. I have kept the print going and turned the stepper motor current regulator all the way down on the RAMPS boards until the motor refused to turn at all. I then went all the way up at 1/8 turns but never reached a point where the motor stopped skipping until I suppose I maed out on the over powered side as again the motor simply refused to turn. I have tried every where in between but the motor still skips and I have looked at the troubleshoting and calibration pages. I also have a fan blowing directly on the extruder motor its self with two heat sinks and it does feel warm but not too hot to the touch.

The second problem is that our edges in the test cube are not sharp or uniform. Which settings should I look at for trying to clean up the edge sharpness?

I look forward to your replies and thanks for the help!

-UNF3D

P.S.- Why does LED4 constantly flash? Last night I noticed it. Just now I see that LED3 is on steady as well and LED2 as well... What does all this signify?

Edited 1 time(s). Last edit at 04/15/2014 01:02PM by UNF3D.

---

[www.facebook.com]

for the extruder - things to look at:
the heat setting - what ttemp are you printing at? does the temp drop durring printing? can you push the filamet by hand easily? what type of extruder? I'm guessing that the extruder does not jam as you are able to continue printing? does it skip even without a load? check the wiring. plug your x motor into the extruder motor output, does it skp? swap motor drivers, does it skip?

sharp edges - need a picture, but if you are not extruding correctly, then you will never get desired results, that needs to be fixed first.

LED4 is the hotend, it flashes because it is using PWM - seending pulses to the hotend to keep it at temp. (it will be soild until it reaches near temp, or should)

Printing PLA .3 mm at 205 with no flucuation in temp during the print. Flow rate is 110. Looks to be laying down really nice etrusion but about 15 to 20% in to the cube print it begins stalling. Are you saying I should unplug the etruder motor from the ramps board and plug the motor in its place? Do I do this when the printer is off then try to run the print? Do I put the etruder motor into the - slot? Sorry we are noobs but give us links and we will put in the effort!

If the extruder works for the first 15% and then starts skipping, it is likely to be something in the hot end jamming up.

Try RichRap's 2finger test from [issuu.com] and see how it compares with when the stepper skips.

Messing with the trimpots on the stepper driver might be a distraction--they put put the same current (and the same torque) into the steppers whether they are running, still, or skipping, and the setting works for the first part of the print. (You might measure the voltages on the trim pots/currents per something like "current limiting" on [www.pololu.com] so if folks twiddle with the trimpots, you can easily get back to a known good state.) Since the power/torque in stays the same, then the intermittent skipping is caused by either the filament coming in (binding), the filament out (hotend jamming), or something else in the cold end. I'd guess it's in the hot end.

Quote
UNF3D
Printing PLA .3 mm at 205 with no flucuation in temp during the print. Flow rate is 110. Looks to be laying down really nice etrusion but about 15 to 20% in to the cube print it begins stalling. Are you saying I should unplug the etruder motor from the ramps board and plug the motor in its place? Do I do this when the printer is off then try to run the print? Do I put the etruder motor into the - slot? Sorry we are noobs but give us links and we will put in the effort!

Just swap the moter plugs to see if it is a driver. Could be the driver is over heating. Do you have heatsink and/or a fan on the ramps board?

Turns out for some reason the large gear on the etruder assembly with the two way nut is tightening during prints until the stepper motor can no longer turn it. I am trying to find a solution. I have successfully printed a nice cube and am.. 36% into Yoda now but have had to loosen the gear nut twice when the motor began to skip so obviously I need to find a long term solution.

Do you have double nuts locket together with wrenches and a little thread locker blue. This is been one of those bad designs that is been in reprap for a long time I would never design a Rotary device like this. I've never tried it but you could try to use a split shaft collar the size of the bolt placed over the threads and tightened their ment for smooth shafts but might be enough to clamp down on the threads to get away from the the nuts. I don't know how mechanically inclined you are but the right way to do it with threads would be to have a split collar that was threaded that clamps to the bolt one can be made or possible purchased

Edited 5 time(s). Last edit at 04/16/2014 03:16AM by cnc dick.