Tail Stock Slop SB 16

[no1boatguy]

Hi Everyone

I have a problem with slop in my tailstock quill. I was trying to align the tailstock with the headstock with an alignment bar but the tailstock guill keeps moving. I put an indicator on the quill and with it extended to the 5 inch line there is 10 thousandths play pulling the quill toward me by hand. Pushing the quill away there is 2 to 3 thousandths. Retracted to the 2" there is 5 thousandths pulling toward me and 1 thousandths pushing away. The vertical movement up is 9 thousandths and the down is 1 thousandths.
Measuring the quill removed from the housing using calipers it does not seem out of round. The diameter is really consistent at 1.86 in the quill The bore in the housing is measuring 1.87 inches so about 10 thousandths larger than the quill. Would the quill or tailstock housing be worn? I don't have any data on the bore size of the tailstock?

Thanks
Dan

 

[Bob Korves]

You can bore the tailstock and make a new quill to fit, or just make a new quill if the hole is round, not tapered, and is in line with the spindle.

 

[benmychree]

More than likely, the quill is not concentric with the headstock spindle this is easily checked with a dial indicator, and also you could remove the tailstock and check for a unworn spot on the bottom of the tailstock; The cure is to rebore the tailstock body and make a new quill to fit snugly; I recently described the process of doing so on HM, but could repeat it if you are interested in doing it.
I would expect that the quill to be less worn than the quill, but some careful measurements can quantify and qualify where the problem lies.
I think it is important to pursue the problem, as it can be very frustrating to achieve good accurate work with the situation that you describe. If there is indeed .010 clearance between the bore and quill, that is way too much, should be more closer to .001or a little more, say .0015.

 

[Bob Korves]

Has anybody hard chromed a tailstock quill, ground it round, and then bored or honed the tailstock housing to fit? That seems like a repair that would last a long time.

 

[benmychree]

Has anybody hard chromed a tailstock quill, ground it round, and then bored or honed the tailstock housing to fit? That seems like a repair that would last a long time.

The only thing is that does not address alignment problems such as quill height and parallelism with the spindle; Ground hard chrome would indeed be good, but expensive.

 

[Bob Korves]

The only thing is that does not address alignment problems such as quill height and parallelism with the spindle; Ground hard chrome would indeed be good, but expensive.

I expect that if you bore a tailstock housing that it would be best to line bore it on the machine it will be installed on. ???

 

[benmychree]

I expect that if you bore a tailstock housing that it would be best to line bore it on the machine it will be installed on. ???

Yes, that is what I did, made a line bar with bushing supported by the steady rest, pushed the tailstock with the carriage, weighted it to hold it down, can supply more details if the guy wants to do it.

 

[no1boatguy]

Thanks for the reply's

I am trying now to get the factory dimensions of the bore in the housing. Currently just using cheap digital calipers. I get a reading pretty much consistent around the circumference of the quill at 1.86 inches. The bore hole ID on the housing is 1.87 inches all around so 10 thou difference. I am checking on a new old stock quill . I am told that the diameter is 1.875 inches but is still being verified as I write this so not sure yet. So if it is 1.875 replacing the old quill with the new quill would go along way to tightening the tolerances. The problem for me right now beyond being a beginner to all this is I don't have any other machines to attempt to make my own parts so have to take it to machine shop for bigger bucks into the problem.

Dan

 

[benmychree]

Thanks for the reply's

I am trying now to get the factory dimensions of the bore in the housing. Currently just using cheap digital calipers. I get a reading pretty much consistent around the circumference of the quill at 1.86 inches. The bore hole ID on the housing is 1.87 inches all around so 10 thou difference. I am checking on a new old stock quill . I am told that the diameter is 1.875 inches but is still being verified as I write this so not sure yet. So if it is 1.875 replacing the old quill with the new quill would go along way to tightening the tolerances. The problem for me right now beyond being a beginner to all this is I don't have any other machines to attempt to make my own parts so have to take it to machine shop for bigger bucks into the problem.

Dan

It would take a micrometer and telescoping gage to accuratately evaluate the wear and clearance situation. Trying a NOS quill would tell you a lot too.

 

[Silverbullet]

All that movement with the quill locked?? I don't think the tailstock should be 5 in hanging out to Ck for offset tailstock.