Clicking Noise - X & Y Axes

the end condition on the non thrust side is not critical. All the thrust comes from the Stepper side. all that bearing has to do is keep the end of the screw in the correct place. The load in any direction other than the direction of the ballscrew is covered by the rollers.

The holes are slightly larger than the bearing to allow for some float. if the ballscrew end is pulled in any direction out of axis centre then it will pinch the brass nut and stall..

so the clicking is fine - as long as the thrust side is fixed in place with no backlash. thats the most important aspect.

Major stress until I read this thread!

I just got my machine fully assembled and running like a three dimensional dream this afternoon. I still have issues with axes moving the wrong way when homing and limits being lit, but I noticed the X axis lead screw rattling in the bearing and when I looked further there was considerable (0.25 - 0.50 mm) float between the bearing and the rebate in the gantry upright.

Anyway, now I know the reason for it, it's all back together and running like a 3D dream again. Phew!

Doug

I had a slightly different problem on my 840, clicking as yours but also severe jamming when nearing the front end of Y-axis. I did not have any play at all in the front end thrust bearing, it was only when I loosened the front end plate bolts that it ran free. I eventually put shims in between the rail and end plate, .020" one side and .024" on the other. Now I have about .012" clearance between the screw and thrust bearing with all bolts tight, it now runs without jamming. I thing that either the rail is too short or the screw too long, but it now works a treat so who cares. Now to try and figure out vectric!!! :huh:

Steve,

I believe that the majority of Y axis 'mechanical tuning' issues that people are experiencing are due to the inability of the end plates to align correctly and lack of some free play in the bearing rebates.

The above is more likely due to powder coating overfilling the holes and perhaps mounting screw hole positioning being slightly off. This will tighten the lead screws particularly at each end leaving no scope for the Y axis roller assemblies to align the lead screw as they move.

It seems counterintuitive but there needs to be some free play in the lead screw mechanism. Largely speaking the roller assemblies in the extrusions take care of alignment while the lead screws provide linear drive motion, not alignment primarily. This must be a characteristic of the lead nut/lead screw drive type and will be more of an issue the larger the machine.

My aluminum T slot bed is also a very precise fit and is likely constraining the available extrusion movement somewhat.

I have enlarged the size of the bearing rebates and the screw mounting holes with diamond files in both front and rear plates to avoid them misaligning the extrusions or applying stress to the lead screws when the mounting screws are tightened. Now both Y axis lead screws turn easily over the full range using fingertips only!

Once the customer accepts these slightly unpalatable facts, life gets much easier 😉 Sadly most of us don't find out that there is a problem until the machine is fully assembled. By that time, it is relatively easy to remove the front plate but the rear plate involves more work.

Personally, I would have designed the end plates to interlock with the extrusions to remove the guesswork out of the macro alignment and designed in enough free play or adjustment range in the bearing rebates to allow some float in the lead screws.

Doug