You will need to explain how far you have got with the firmware configuration, and have you connected to the firmware from the PC with software such as Pronterface or Cura. The firmware may not allow the stepper motors to run if there is no hot end temperature sensor connected. Also, the stepper motors will not operate properly if the end stops are not configured correctly.

It might take a few posts to get you sorted and it might be better to post your question on 3D Printing google group for faster response; link below.
https://plus.google.com/u/0/communities/117814474100552114108

Glad you got sorted, the jumpers are easy to miss since they’re hidden.

I’ve tried the auto bed levelling but abandoned it, not really needed for my type of 3d printer. I don’t think the servo implementation is very popular, using the hot end as the end stop seems to be better, especially with the delta type 3d printers.

According to the comment in the Marlin firmware code, the probe servo is only switched on during movement. So, why the servo is twitching, it’s a mystery to me for now. However, could a stepper motor nearby cause the twitching?

Mark

Thanks for the reply. I was able to get them working properly. I forgot to attach the jumpers to the pins under the stepper drivers. I have a new problem though. I am using a servo motor and z probe with an endstop attached to it for a bed leveling system. When I hit print, the servo automatically starts jerking the whole time, kind of like twitching but not actually moving anywhere. It does this for the entire duration of the print. Any ideas what this could be?

Thanks,
Chris

The homing of each axis is what you need to test first, Jogging will not work properly otherwise.
Home X, Y and Z separately first, checking that stepper motors are turning the correct rotation direction with the axis going towards the end stop. Set the axis at centre of travel before running the test to avoid an axis crash, be ready to cut power in case the axis goes the wrong direction.
Run through this Pre-flight check for good measure:
http://reprap.org/wiki/RAMPS_1.4#Pre-Flight_Check

Mark

I am building my first 3D printer, and I have ran into some troubles. I have built the printer, and have it wired to a RAMPS 1.4 with and arduino Mega 2560. I successfully flashed the marlin firmware onto the board. I then used repetier to control the printer. I went and tried to manually jog the axis to see how they worked, and that is where the problem lies. When I jog them 1mm, they turn a little bit, then start turning the opposite way, even though I am still jogging the same direction. When I try to jog them 10 or 100mm, the stepper motors make noise like they should turn, but they don’t turn at all. Any ideas what could be going on?

Thanks

It’s not a quirk I’ve seen before, but it’s strange that you get two different results with the same g-code.

To help pin point the problem, a test can be done where we can issue some instructions to the printer, then measure the output against what is expected.

;Z-TEST.GCO
G28 ;Home all axis
G1 Z0 ;Send Z axis to 0 Pos.
G1 Z50 ;Send Z axis to 50 Pos

The above G-code, saved in text file Z-TEST.GCO, is an example of a test you can do to check the travel distance of the Z axis after some motion. Load this file in Pronterface and run, then measure the distance between the bed and the Z axis, check the distance travelled against the g-code for a match. Run the same file from the SD card and check the distance as before. You can use Pronterface to upload the file to SD card, but run the file through the printer control interface.

You can choose a travel distance to test to match the width of a tablet box; or anything that will fit between the nozzle and bed to easily measure the distance travelled.

If there is a travel distance mismatch, run the same file a number of times in a row and check the distance travelled each time; we are looking for consistency between tests.

The next step of solving your problem will depend on the output of the above test.

Mark

thanks for such great info on 3D printing. I’m new to the 3D printer world, and have built a Prusa I3 with Reprap Discount RAMPS 1.4 and Marlin. In fact, I downloaded your Marlin firmware as a starting point.

My printer works pretty well, and I have now started trying to use the 4×20 lcd panels SD card slot. I have a problem with the Z axis when printing from SD card. My prints come out dimensionally correct in both x and y axis, however the z axis height of prints is about 25% too small. I hooked up with the IRC channel and a guy there suggested the SD cards prints try to run at full speed settings as set in the firmware. I’m not sure if this is the case or how the firmware does this, as I thought that the gcode (generated by slic3r) defined the speed settings for the print. I used the same gcode for printing from pronterface from my MAC and from the SD card, with the height difference in z axis only evident from the SD card print.

I wondered if you have seen this quirk before and have any ideas what the problem might be?

Regards,

Graham