Reassembling KRV2000, unsure on Y axis shims etc.

[carl0s]

Hi.
I am very slowly reassembling The KR-V2000 BP clone that I bought recently. I had to disassemble it to get it home.
I am spending a lot of time trying out various combinations of washers, shims and spacers and not being quite sure I'm doing things right.

It seems that on the Y axis, the backlash in the movement of the saddle is set with the shims in the handle - those between the handle and the power feed gear. Am I understanding this correctly? The end-cap stops the leadscrew from actually unscrewing out the front of the machine, but it still screws in and out until the ideal amount of 'stuff' is fitted to the outside of the shaft - the bevel gear of the power feed, some shims, washers, and the handle (which in my case is those safety-handles).
If I don't have the ideal length of 'stuff' on the outside, then I have a ~1mm gap there, and turning the handle simple takes up that space as the lead screw moves back into the machine.
Is that correct? There's nothing actually holding the leadscrew in place at the rear, so I can't see it being any other way.
Unless I am supposed to use some sort of spacer or shim between the screw and the inside of the end-cap, so that the screw is up against the back of the machine or something? but I don't think that's right.

 

[carl0s]

Think I have sorted that. I had left out the power feed's bearing race. Put that in, and I seem to have about the right amount of 'stuff' (collars, shims, washers) on the end of the shaft to create the right space.

Is this what you call end-float, rather than backlash? either way, it's minimised now.

 

[OTmachine]

On conventional machines you will (pretty much always) have Backlash when changing feed direction. Learn to adjust and compensate for it. If you have a DRO, you can minimize locational error using your backlash eliminator when changing directions. My .02

 

[carl0s]

Hi.
It's not so much just on changing direction. I could grab the saddle and pull it forward and backwards and it'd move at least 1mm, with most of that showing up as a gap between the dial and power-feed.

I've correctly shimmed the handle-nut now, which mostly cured that. I just didn't realise that end float in the handle nut affected the table/saddle but it does. It makes sense, it's just that I'm new to all this. My lathe has its leadscrews retained on both ends. The Y-axis on the mill just sort of floats.

After doing that, I still had some play in the saddle. My leadscrew is a bit worn. I can adjust it out with the yoke-nut adjustment, but then it's too tight in other parts. I think I have found a reasonable compromise, but I might buy another nut and screw set anyway.