Saturday 26 December 2020

Cross slide ballnut yoke(s) - reassemble lathe for manual operation

"Switch to manual"

Firstly, I need to get the lathe back together again, so I can do some lathework - stuff like the ballnut yoke, ballscrew machining etc. "Physician heal thyself" etc.

Then I can start by machining up the ballnut yoke. 

Reassembly:

Had to do some radical degreasing, scraping out etc to get years of gunk out of all the crevices and threads. Here's the rear saddle gib. Like the other gibs, you loosen off the clamp bolts, adjust the gibs, then tighten up the clamps again.


These are the front brackets. Unlike the rear gibs, there's no adjustment. That's presumably because all the cutting forces press the saddle onto the bedways.


Here's the cross slide:



The gib adjusters are a series of grub screws.


I needed to clean the threads using a set of UNC taps.


The saddle can move all the way along the bed when there's no rack limiting movement.


That's potentially 540mm of movement.



Machining the ballnut yoke:

Finally ready to do something now. The blank is a bit of cold rolled steel that I squared off and roughed out on the mill - 28.5 x 24 x 40mm. Now I need to drill and bore the 24mm dia hole for the ballnut. then I'll place the fixing holes in the mill using the bore as a reference.


Ready to go...

Ooops. Fuckit.

Somebody got a bit carried away with the boring tool. 


Ah. I seem to have overbored the thing. You can see the imprint of the jaws!


The other side is barely there.


And I seem to have given one of the jaws a new finish.


Time to cut a new bit of stock and start again


It's barely one piece..


What a fucking idiot.

So - start again with another chunk of steel:


Dial it in - again.


Finally. A slide fit.


Next - fixing holes for the ballnut and cross slide body, then finally machine off the bottom, flush with the bottom of the ballnut.

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