building and perfecting prusa i3

First of all excuse me for my english,I'm new to 3D printing. As a step to the world of 3D printers i build a prusa i3. Which is working but not smooth as it should be. I'm thinking about modifying my printer.
I've added a servo controlled auto bed leveling systen which is done by repeatability test but still the values obtaining from the method changes each and every time. Not getting a good result with it tried everything nowadays i'm spending more time on calibrating those than printing. My axis including E axis is also calibrated. any help on that will be appreciated

I think major problems result due to banding of Z axis i guess. I'm thinking about changing M5 rods on Z axis to lead screws or so. but does lead screws gonna reduce acheviable resolution??? cause I'm thinking of M8 lead screw with 2mm pitch am I on right direction?????

Well, it's difficult to know where do the problem come from. Each part of the machine can cause repeatability problem. If the Z endstop is not properly maintained, Z height may change at each measurement.The same for the auto level probe. If you have some wobble from your rails, measurement can't be accurate. I think the rails and the overall flex of the machine are to blame before the 5mm rods. The resolution of the 5mm threaded rods is sufficient and adapted to the i3 needs. The Z axis moves one time by layer, and in a single direction. The possible backlash in the nut is not realy a factor in this design. You can change the nuts for some zero backlash Derlin nuts, and if you like, the whole transmission for ballscrews but I'm afraid that won't change your problem. Don't spend some money befor to be sure you reached the best from your printer. Find from where comes the wobble. Try to tight all things up first.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

@Zavashier

I'm using 10mm acrylic sheet as frame(single frame type). The wooble on Z axis M5 rods is really visible. I think whats made all wrong is that the M5 nuts in the x motor mount and idler mount used to come out so i used some araldite to fix them in the nut holes I think that made Z axis rod to bend and resulted in woobling. so I'm planning to change the idler and motor mount so along with it thinking about leadscrews

does M8 leadscrew with 2mm pitch is capable of producing same resolution as M5 threaded rod with 0.8mm pitch (its good to have low pitch rite?)??? i see some machines like Aluminatus using leadscrews in all axis.

Edited 1 time(s). Last edit at 11/24/2014 10:09AM by jhondon.

If your z-axis nuts fall out then your z-axis rods are not smooth enough or you have mounted the x-axis idler and motormount upside down.
For the wobble: let the top off the z-rod turn free, not in a bearing or so.

Hans

@gforce1:
First of thank you, andI don't have any restriction for threaded rod on top. I'm attaching a photo of X axis assembly

does anyone have designs of x axis motor mount and x idler accepting M6 rods?
thanks in advance..