Z axis binding

Hey everyone,

I just completed my mendelmax a few days ago, and I am getting occaisonal binding on my z axis, and I really cannot figure out why.

As best as I can tell, my rods are all perfectly leveled, and my x axis is perfectly parallel to my bed.

It does not happen every time, and the amount that it happens varies.

Last night about 1/2 hour into a print, my 3rd print on my printer, I noticed that one z motor was binding and the other was not, and it got my x axis off center and ruined my print.

Since than, I have been manually playing with positioning in pronterface, and moving it up and down.

It only happens once out of every 10 times or so.

I added a good amount of WD40 to my threaded rods, which seemed to help, but not completely eliminate it.

I do notice some wobble in my z axis where my couplers are connected to my stepper shaft.

Anyone have any suggestions for me on how to correct this? Kind of at a loss for what to try now.

If you find the z shafts are wobbling around - perhaps the hole in the x-ends is not quite big enough? I know I had to slightly enlarge the circular hole whether the threaded rod goes to stop binding happening. You might also want to check your motors are correctly positioned and not a little bit to one side.

Sounds to me like the smooth rods are binding on the z bearings occasionally.

James and waitaki,

Thanks for the replies.

James,

I don't think it's the holes int he x ends because I can see the rod that is binding and on neither the top nor bottom does it seem to be even within a mm of the plastic, my setup has a bearing in the x end and the threaded rod is pretty well in the bearing.

I think waitaki is right, but I am not exactly sure.

It's very odd, it will go several prints without doing this, I can manually move it all the way up and all the way down with no binding, than all of the sudden it will happen again.

I am not quite sure what to do about it.

Well, I haven't looked at a Mendelmax much so the following may not apply, but anyway....

The smooth rods on the X axis, when they are inserted into the x ends (idler and motor), should allow the whole X carriage to slide up and down smoothly on the Z bearings BEFORE the x rods are clamped in the x ends (can they be clamped?) When I say clamped I mean TIGHTLY clamped. Only then can the x axis toothed drive belt be fitted and tensioned. Tensioning the belt before clamping the rods will lead to binding. The reason I changed to Jonas Kuehlings X ends (http://www.thingiverse.com/thing:18384), was because of the positive clamping of the Ends. The drive belt puts lateral forces on the x ends and must not be allowed to distort them.