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View Full Version : the BP Xfeed nut ...?



madman
06-25-2007, 05:30 AM
I finally cut my bridgeport nut at the split in half. Then off to the lathe and lightly face each end to cleran up. I assembled the two pieces in proper order (as prior to dissassembly) and when screwed together it had zero lash or play. BUT the key slot does not line up. Now i am assuming (Yeah Right) that you simply unscrew it the 3/4 turn leaving a space between the two halves and then reassemble into machine and set screw it tight and voila no backlash?? Is this correct?? Or do I screw it together and then mill a new key slot in the half that doesnt aline up its key slot with the other key slot in the other half (dont ask me to say that 5 times really fast) Thanx Mike

Bill in Ky
06-25-2007, 10:15 AM
Use the keyway it had. The space between the two pieces of the nut is what gives you the adjustment for backlash.

pcarpenter
06-25-2007, 05:09 PM
You thread both pieces of the nut onto the lead screw in the same order they came off, with the slot in alignment. If the whole affair is put back in just like it came off, the nut will be no longer or any differently aligned than when the nut was still one piece. You do not screw them together until they touch. You leave the small gap that would have been there before you sliced it through and use the adjustment screw to pinch the two halves together to adjust out the backlash.

I find it easierst to install both nut halves on the lead screw and then slip the lead screw with the nut halves attached and lined up (key way), back into the bore they came out of the same way they came out. The backlash is adjusted minimal then by use of the adjusting screw you would have had to have removed to get the nut out in the first place. Since the back half of the nut is captured in place by a ridge and the adjusting screw squeezes the two halves together, you have the ability to adjust out the runout.

As previously mentioned, I think the manual recommends .005 as nominal. Zero runout is almost sure to accelerate wear.

paul

madman
06-26-2007, 05:14 AM
I thought so yet when i screwed them both together it was a perfect no backlash fit .I then thought HMM maybe i should key it and reassemble but i will do as i just read. Thanx Guys much appreciated