# Is this the backlash or something else



## Bamban (Dec 31, 2014)

Today asI was cleaning the lathe after doing a project, for laughs and giggles I chucked in a test bar and stuck an indicator on the bar to see how well the head to ways alignment I did was holding up. The alignment appears to be just fine, then for whatever reasons I decided to do some checks for anything loose. When I got to the cross slide I pushed and pull and I could hear and feel a definite movement. The indicator verified the movement - 0.006.

The backlash on the cross slide happens to be 0.006 as well. The question, is the movement I noticed the backlash, just displayed/exhibited in a different way?

The video is not very clear, but if you look closely at the indicator by my left hand you can see the hand moving with push/pull. The compound is solid, I was just using the tool post as a convenience item.


View My Video



Thank you.


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## kd4gij (Dec 31, 2014)

That is back lash.


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## Karl_T (Dec 31, 2014)

backlash, and not very much either


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## Bill Gruby (Dec 31, 2014)

You have .006 backlash in the cross slide.

  "Billy G"


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## compsurge (Dec 31, 2014)

Mine rocks on the bed from right rear corner to front left (where bed wear is ~0.010"). Do you only have movement along the axis of the leadscrew? Verify the leadscrew nut is tightened to the saddle. Otherwise, 0.006" backlash isn't really anything to worry about and is actually pretty good. That's about what I have after tightening the cross slide nut (0.008" compared to 0.060" prior). I also tightened the gibs on the rear of the saddle to help with the rocking.

Are you getting any odd patterns on the cuts?


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## rafe (Dec 31, 2014)

You could, after you push it away from you the .006 on the dial indicator....go ahead and tighten the handle .006 and you should take out the backlash to where you shouldn't be able to pull it back to you. That really isn't a lot of play I think my SB had around      .040 or more before I replaced the screw and nut and I was able to work around that much backlash....


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## Bamban (Dec 31, 2014)

compsurge said:


> Mine rocks on the bed from right rear corner to front left (where bed wear is ~0.010"). Do you only have movement along the axis of the leadscrew? Verify the leadscrew nut is tightened to the saddle. Otherwise, 0.006" backlash isn't really anything to worry about and is actually pretty good. That's about what I have after tightening the cross slide nut (0.008" compared to 0.060" prior). I also tightened the gibs on the rear of the saddle to help with the rocking.
> 
> Are you getting any odd patterns on the cuts?




Thank you.

No rocking L-R nor diagonally, just F-B. As far as cuts, had taper before, took it out by adjusting the headstock using Brian Miller's MT5 test bar.  Since I intend to do some barrel work eventually, I set up the set tru chuck with a 1 inch test bar. I periodically check the alignment and chuck run out with the same 1 inch test bar. As I mentioned in the original post, it was in this test when I discovered the movement. 

Is the lead screw nut the same one holding the crank?


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## Hawkeye (Dec 31, 2014)

The nut he mentioned will likely be the one that rides on the leadscrew and is attached to the part that moves. Quite a few of them are designed with the ability to tighten them a bit on the leadscrew. Just enough to take out excessive movement, but not enough to make it harder to turn the crank.

6 thou backlash would make a lot of us giddy. I wouldn't worry about it for manual work.


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## Bill Gruby (Dec 31, 2014)

The crank nut is the one you can see on the center of the crank handle. Look closely at it If there is a set screw in the center it will, when loosened allow you to tighten the nut to take more of the back lash out. Once you get it where you are comfortable with it tighten the set screw and it locks the nut.

 It may also have two jamb nuts instead. 

  "Billy G"


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## Bamban (Dec 31, 2014)

Bill Gruby said:


> The crank nut is the one you can see on the center of the crank handle. Look closely at it If there is a set screw in the center it will, when loosened allow you to tighten the nut to take more of the back lash out. Once you get it where you are comfortable with it tighten the set screw and it locks the nut.
> 
> It may also have two jamb nuts instead.
> 
> "Billy G"



Billy,

I checked the crank, it looks like there is no set screw and only one nut, and the nut is super tight as it is, could not budge it


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## Andre (Dec 31, 2014)

If you try and asjust the nut for 0 backlash, then you will be bearing on both sides of the acme nut and it will wear out or need adjustment rapidly. Can you lock the cross slide when taking a cut to avoid taper?


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## Andre (Dec 31, 2014)

Just noticed in your sig you are a Distinguished Rifleman, that's quite the award! Working towards mine, need 6 more EIC points. What are you distinguished in, Hipower? If so, service rifle, 300m?


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## hermetic (Dec 31, 2014)

Lock the carriage/saddle to the bed and try again, if you have only 6 thou in the cross slideyou are fine!


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## Bamban (Dec 31, 2014)

Andre said:


> Just noticed in your sig you are a Distinguished Rifleman, that's quite the award! Working towards mine, need 6 more EIC points. What are you distinguished in, Hipower? If so, service rifle, 300m?



Distinguish in High Power, 1996, service rifle.

Congratulations, 6 more points to go, you will get it at the next match.


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## Bamban (Dec 31, 2014)

Andre said:


> If you try and asjust the nut for 0 backlash, then you will be bearing on both sides of the acme nut and it will wear out or need adjustment rapidly. Can you lock the cross slide when taking a cut to avoid taper?



The taper has been adjusted out when I adjusted the headstock using the Brian Miller's MT5 test bar. I do lock the cross slide when I make the finishing pass, just for insurance.


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## Bill Gruby (Dec 31, 2014)

In the lathes we use there must be some backlash. Backlash is a product of both parts, nut and screw. At zero backlash all surfaces of the thread, nut and screw, are touching. When this happens the assembly ceases to turn. CNC relies on anti- backlash nuts. Whole different animal.

 "Billy G"


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## Bill C. (Dec 31, 2014)

Bamban said:


> Today asI was cleaning the lathe after doing a project, for laughs and giggles I chucked in a test bar and stuck an indicator on the bar to see how well the head to ways alignment I did was holding up. The alignment appears to be just fine, then for whatever reasons I decided to do some checks for anything loose. When I got to the cross slide I pushed and pull and I could hear and feel a definite movement. The indicator verified the movement - 0.006.
> 
> The backlash on the cross slide happens to be 0.006 as well. The question, is the movement I noticed the backlash, just displayed/exhibited in a different way?
> 
> ...



.006 is pretty good.  I have worked with worse.  If you are concerned about repeatably of your cross-feed use a indicator like you have setup.  I have done that several times to be sure I had all the backlash out.


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## Bamban (Dec 31, 2014)

Hawkeye said:


> The nut he mentioned will likely be the one that rides on the leadscrew and is attached to the part that moves. Quite a few of them are designed with the ability to tighten them a bit on the leadscrew. Just enough to take out excessive movement, but not enough to make it harder to turn the crank.
> 
> 6 thou backlash would make a lot of us giddy. I wouldn't worry about it for manual work.



Thank you.

I ran the cross slide away from the operator side as far as I could to see where that nut is, sure enough there is one and it has a socket head what appears to be an adjustment accessible from the back. Without taking the back splash I just reached over and felt the piece. I grabbed the socket head with my fingers and I could turn it, needless to say, it is loose. By just tightening with my fingers I was able to remove 0.001 from the movement. Grabbed an Allen and tightened it. I stop at 0.002 movement. The crank still feels the same so I don't think I over did it.


View My Video
View My Video


The question is that adjustment too tight?


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## Bill Gruby (Dec 31, 2014)

.002 is great. No it is not too tight. Most of the guys here would kill for .002. 

  "Billy G"


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