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Tutorial Upgrading the Proxxon Micro Compound Table KT 70

@Jimsky with the upgrade of these bearings is the backlash also gone?

Some video to the subject of the subject

The first video need to be start from the beginning



And a wonderfull tutorial you have made. Love it.

I got the bearings in my stock, but I did on the z-axle only and when using the MF70 the z-axle is very loose and likes to go out of position now. How is this with the bearings in the table?
 
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I have knock-off version of this table, looks exactly the same. Probably Chinese. The back lash on the screws is terrible, if performing this upgrade would cure the problem I think I have to do it.
 
The backlash is a gap in carriage leadscrew thread teeth and the carriage nut thread teeth. Large backlash is not getting fixed by placing some thrust bearings on the lead screw handle. This just reduces friction in leadscrew system and makes turning of leadscrew easier. Nothing to do with reducing a backlash. Sorry to discourage some people.
 
Y.T. said:
The backlash is a gap in carriage leadscrew thread teeth and the carriage nut thread teeth. Large backlash is not getting fixed by placing some thrust bearings on the lead screw handle. This just reduces friction in leadscrew system and makes turning of leadscrew easier. Nothing to do with reducing a backlash. Sorry to discourage some people.
Click to expand...
Sorry, but I don't agree with that. In this case, the backlash is caused by deformation of the plastic parts Caused by friction. This deformation has been virtually eliminated by these bearings, which reduce friction considerably. After replacement, the backlash is less than 1 unit on the rotary knob for me. This corresponds to 0.035 mm. Previously, it was at least 0.15 mm. (3 to 4 units on the knob). And I think that even if I install the bearings better by positioning the nuts more accurately so that the friction is reduced to zero (without the carrying nut fixed), that last bit of backlash will also disappear. But I can very well live with an inaccuracy of 0.035 mm.
There is no play between the screw thread and the carrying nut.
In fact, the xy table does not move much more easily after installing the bearings, because the carrying nut moves very tightly over the screw thread.

The Z-axis is a slightly different story; it rotates much more easily and the backlash has decreased slightly. But I don't see that as a problem because I have mounted a digital caliper on it that indicates the exact upward and downward movement.
 
Steef66 said:
There is no play between the screw thread and the carrying nut.
Click to expand...
The term backlash is ONLY the play between leadscrew thread and the carriage nut. If you don’t have this play you don’t have a backlash (which still must be there to some amount as otherwise you could not rotate a handle). The rest of carriage movement is just loose lead screw. This is being adjusted with or without thrust bearings. Just with thrust bearings it is easier to rotate a handle.
 
Thanks Stephan for sharing your method to attach a DRO to the Z-axis. I copied your method with a $7.00 digital caliper.
IMG_9081.jpeg

At the moment it’s attached with 2-sided tape as a proof of concept. I ordered some M3 machine screws and will tap some holes to attach the brackets. In the meantime this solves the backlash issues.
 
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