Crossfeed table slop

D

duster340

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tore down my midas LTD to replace the half nut and the crossfeed nut. Cleaned things and reassembled. I cannot , however seem to get the backlash out of the cross feed table.Didnt measure , as the eyeball made me plenty aware that its much more than desired . Wondering about wear in the cross slide ways , and if maybe modifying , making , or having made a gib that tapers toward center could resolve it, as in one thats thinnest point is center , and tapers larger towards each end?
 
Short answer is NO. If your dovetail is worn more at one spot than at some other spot, the only fix is to replace or maybe re-cut the dovetail. But that is not backlash. Backlash would be for example turning the crossfeed crank for several degrees of turning and then the cross slide suddenly begins to move. And if you start turning the cross feed crank in the opposite direction, again nothing moves except the crank and screw for several degrees rotation and then the cross slide suddenly begins to move in the opposite direction.
 
Does the feed screw nut have a backlash adjustment ? On my lathe there is slot cut into the nut perpendicular to the threads, with a locking screw.
By tightening the screw this closes the slot which reduces the clearance in the threads relative to the screw.
Maybe cut a slot in yours and put in a screw.
 
That will only work if the cross-feed screw is not worn in the area that most work is done in. If it is and if you adjust the nut clearance to minimal back lash, you will not be able to crank the cross slide clear of the screw.

There is also another source of "back lash" that tightening the nut will not have any effect on. This is end-float or end-play in the cross feed screw. This should be adjusted to as near zero as you can tolerate it with the nut run clear of the screw.
 
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In my post I assumed the screw and nut were in good condition
 
If they are, then you need to tighten up the screw end float. This is usually done by differential adjustment of the position of the hand wheel on the screw. Note my correction of my previous post.
 
Anyone come up with a fix.
I recently picked up a CB1220XL
The back lash was awful
The cross feed nut just sits in a hole and a stub protrudes from tne nut. Lots of slop there to start with.
Now specs from smithy say .008-.015 is with in spec for this machine.
I also found the cross nut “plate” screws completely backed out.
Once I got every thing cleaned and back together I found putting the cross nut “ plate” a thread or so away from the nut and adjusting the screws from that point gave me a good amount of adjustment.
Before I had about 1/2+ rotation of the dial. Im down to .010 is now.
I dont think it can get much better with out replacing the nut?
 
On whether or not to replace the cross feed nut, run the nut almost off of the screw, which is a position that it would not normally ever get to and therefore no wear on the screw. If end float is still excessive, replace the nut. If not, and if the nut is still not loose in the hole, replacing the nut isn't going to help any.
 
wa5cab said:
On whether or not to replace the cross feed nut, run the nut almost off of the screw, which is a position that it would not normally ever get to and therefore no wear on the screw. If end float is still excessive, replace the nut. If not, and if the nut is still not loose in the hole, replacing the nut isn't going to help any.
Click to expand...
I shimmed the “nut hole” the best I could. Im not even sure how much I want to sink into this machine.
I still need cutters and small odds and ends?
 
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