Inconsistent Movement on X and Y

Ok, so I've finally got my Prusa i3 built and wired, but now the issue of movement arises. At first, I couldn't get anything to move except the extruder, and that very jerkily. I found that by turning down the speed of the extruder a tad in Repetier host, I could get it to run smoothly. However, the axis motors were not as cooperative. I went through the whole routine of adjusting the trimpots up from zero, to no avail. The motors only buzzed and perhaps vibrated a bit when commanded to move. Then, I came across part of a tutorial that involved adjusting the steps per revolution. So I dove into the firmware to see if that might help. I changed it from {80, 80, 3200/0.8, 700} to {40, 40, 2000/0.8, 700}. This gave me movment, but not correctly. The y and x axis moved 5 cm when they should have moved 1, and z continued refusing to move. I fiddled with the numbers for a while before giving up at {43, 46, 1100, 700}. This game me buzzing jerks on z, and inconsistent movement on x and y. To elaborate, if I repeatedly told it to move 10 mm in the + direction, the axis would move 10, then 2, then 7, 15, 3, 10, 11, etc. same for both x and y. However, moving -, telling it to move 10 mm at a time would get 20mm and larger jumps, up to 50 mm. I cleaned and then lubricated the rods, as the movement seemed more consistent towards the middle of the range, which helped slightly.
I'm at a bit of a wall here. Thoughts?

After much trial and error, I got consistent, accurate movement withe the steps_per_unit set thus: float axis_steps_per_unit[] = {5, 5, 500, 700};
This baffled me, as it's drastically lower that the default values of {80, 80, 4000, 700}. Moreover, these lower values, while accurate as the higher settings were not, also produce very loud movement. like, extremely loud buzzing and grinding sounds. Can someone explain this to me? Why do the normal settings cause my printer to skip steps? Am I missing a crucial variable or something?

Sounds like your stepper drivers are set to full step mode rather than microstepping. I'm not sure what electronics you have, but there should be some jumper headers to set microstepping, for x16 you typically need jumpers in all three positions.

I have pololu A4988 stepper sticks, in a RAMPS 1.4. How would I go about setting it to microstep? Nevermind, found the pins underneath the steppersticks. Thanks!

Edited 2 time(s). Last edit at 05/25/2014 03:43PM by dexterousfolder.