compound Backlash

[Ranchingelec]

Hello all. I have been brousing here for a while now and have learned much from you all. I figured it was time to throw a problem out to you fella's hoping you can help me. Last spring we purchased a 14X40 Craftex(sold by busybee here in Canada. It is very similar to some of the acra models I have seen) For things we do on the farm this will be and has so far been a great machine. My problem is with the compound Backlash. It was tight when we got it but after a couple of hours of machining, it loosed up. It could be turned one full round before engaging the threads either way. Upon further inspection I noticed the play was in the thrust bearing on the front of the threaded rod. I disasembled the handle, tighted up the nut and jam screw that tighted the thrust bearing. It was tight for another couple of hours of work. Then I noticed it was loose again. I may have to disasemble the compound further to find out what the real problem is. It seemed that the nut was tight as it could be. Anyways I was wondering if any one has experienced this. Any opinions would be greatly accepted, unless it is about "shoulda not bought that Tiawan product.) lol

 

[cruzinonline]

Well if it was good, then got worse and you found slop in the thrust bearing, tightened the nut and the backlash went away and now it's back the nut is loose again? If it keeps coming loose try some locktight on the nut or change the nut and use one that has the lock built in (plastic band thingy) If your getting back lash it's either a worn nut/screw (clearance in the nut) or you've lost thrust. Sounds like your lock nut is just coming loose.

 

[doug931]

Hi,Rancher. Welcome to the PM forum. You will find some good advise here. If you ask the right questions. I would second the advise to use loctite on the nut.
You have help a lot closer than you think. I live in Cherry Grove and have a fairly well equipped HSM shop. You are welcome to drop in next time your visiting Walmart.

 

[chuckey]

Never seen this piece of kit, but I was wondering if the mating area for the "thrust nut" was rough so the nut picked up and unscrewed. Could try a couple of shiney washers and a bit of grease to overcome this? On second thoughts, as you unscrew the feed screw, there must be a collar or some to stop the handle and thrust nut coming out the front, could this be coming loose?
Frank

 

[g-coder05]

all the acramills and lathes I have ran have two nuts for every axis. The first nut is fixed and the second has slotsts so it can be rotated up to 60 deg. you should be able to adjust your backlash within a couple of though with the second nut. Don't try to get it perfect or you wont be able to turn the lead screw at all.

 

[qualitymachinetools]

Yes make sure to check where there is a collar on the leadscrew that stops the nut from sliding. Some are pinned, some are pressed. Make sure it is pressed on all the way, and make sure there is not a pin that is broke.
Or it might be just the nut coming loose, in that case its already taken care of above.
I had an older Enco 20x80 Lathe, where it was a semi press fit with a roll pin in it, and the roll pin broke. I did not notice. I would adjust, use it for an hour, and gradually the press fit would slip, making the nut loose again. I fought for 3 days before I realized to check the pin, and sure enough from all the adjustments, it moved about 1/2" over that time. So since i realized that the part did not ever need to come off of that shaft even to remove the shaft, I tig welded it on. No more broken pin!