Huge X-Axis droop on delta printer

Hi everybody!

Today I finished building my first 3D-Printer (3DR from Richrap) and I have a strange problem with bed leveling.

If I move the printhead 10cm from left to right along the x-axis in the z=0 plane, the printhead moves up about 15mm. So the z=0 plane is tilted enormously.

At first I thought that one of the motors looses some steps when moving from the home position to z=0. But it is a delta printer, which means if one motor would loose steps it would also affect the y direction. But in the y direction everything is absolutely perfect. No change in height whatsoever along the y axis. How can this be?

Is it possible, that there is some software offset? If yes, where would I have to set it to 0?

I'm using pronterface with a Marline firmware, which was modified as described on Richraps website.

Please Help! I really want to get this thing ready to print now!

On my Delta printer, the Y axis points right at one of the towers. During a straight Y axis move from the center of the bed (x=0, y=0, z=0), the two towers *not* on the Y axis should move in parallel. If they don't, check the micro-step jumpers to see that they all have metal inside and are installed. I'm going to assume that you adjusted your stepper driver voltages with a multimeter, which is another common mistake that causes lost steps.

Another possibility is that the controller doesn't know that the center of the bed is x=0, y=0, z=0, possibly due to an endstop switch being out of adjustment or the firmware/EPROM having endstop offsets configured in software.....

Thank you for your answer!

In the meantime I was able to level the bed (in an awkwardly tilted position) and to produce some testprints of the reprap coin. Which worked very good, beside some unsteady extrusion.

The microstep jumpers should all be ok I think, or the movement would be at least a factor of two off. I use 1/32 microstepping.

Yes, I adjusted my stepper drivers with a multimeter, which other way do you recommend?

I also played around with the endstops and I don't think that's a problem but thank you for the tip with the endstop offsets, I'll look into that tomorrow.

Maybe I should have mentioned, that my printer is fairly tall with almost 700mm build height. While the printhead is coming down from the home position I can see how it slowly moves in the +x direction. If there are really lost steps involved, how can that effect only one axis on a delta printer ....

Quote
CygnusX1985
Yes, I adjusted my stepper drivers with a multimeter, which other way do you recommend?

You did it correctly. People who don't have a multimeter try to do it by counting potentiometer turns or by ear as the motors run, and flying by the seat of the pants usually winds up biting them in the end.

Quote

Maybe I should have mentioned, that my printer is fairly tall with almost 700mm build height. While the printhead is coming down from the home position I can see how it slowly moves in the +x direction. If there are really lost steps involved, how can that effect only one axis on a delta printer ....

Are all three pulleys/sprockets the same size? Did you check that the steps/mm are set the same for all three towers? It might not be a bad idea to swap the endstops and stepper wires between two towers to see if the problem moves to another tower (meaning firmware or electronics) or stays at the same tower (meaning mechanical problem of some sort).....