Aligning the tailstock of a lathe

K

kiinstructor

AzB Silver Member
Silver Member
Hey Guys I need some help with aligning the tailstock of my lathe. I have an older Enco lathe that was made in taiwan I believe. Anyway I extended the barrel of the tailstock which is about 4 inches and locked it down. Then I measured it with an indicator on one end and slid it to the other and found it was off about .20. Thats alot. It has adjustments that allow the barrell to go left and right which are simple enough to adjust but that doesnt correct a crocked barrell. Do I have to shim this? The ways are straight but I think the v grooves that the tailstock has that rides on the ways is out of line. Maybe it was machined wrong originally but Im not sure. Im considering shimming on either end to correct the misalignment but maybe there is and easier way. Your help and ideas are appreciated.

Thanks
Mark
 
Only way to do it accuratly is to chuck up on a piece of stock about 7 inches long with a center drilled hole in it. Bring your live center into it. Take a skim cut off of the stock for say 5 inches.and take a measurement of the piece at both ends of the cut. Put a dial indicator on the tailstock and move it half of the difference you measured. Then repeate until the measurement is the same.
this may help http://www.google.com/url?sa=U&star...-5lbQN&usg=AFQjCNFM-aHxvzhEbFt8LlzBNge0jOaYmA

John
 
kiinstructor said:
Hey Guys I need some help with aligning the tailstock of my lathe. I have an older Enco lathe that was made in taiwan I believe. Anyway I extended the barrel of the tailstock which is about 4 inches and locked it down. Then I measured it with an indicator on one end and slid it to the other and found it was off about .20. Thats alot. It has adjustments that allow the barrell to go left and right which are simple enough to adjust but that doesnt correct a crocked barrell. Do I have to shim this? The ways are straight but I think the v grooves that the tailstock has that rides on the ways is out of line. Maybe it was machined wrong originally but Im not sure. Im considering shimming on either end to correct the misalignment but maybe there is and easier way. Your help and ideas are appreciated.

Thanks
Mark
Click to expand...

You've got me a little lost here. Just where are you taking your measurements from to get this .020 discrepancy? Are you measuring from the carriage rails or the tail stock rails? If there truly is a .020 difference between the front of the rails and the back then it is not your tail stock at fault but either the carriage rails or the tail stock rails are worn. In this case the rails need to be scraped. If the barrel isn't concentric with the bed, meaning, it is a different height when extended than it is contracted, then it needs shimmed between the top and bottom half of the tail stock. If the tail stocks barrel is concentric both when contracted and extended but is at a different height of the head stock spindle, then to correct this is you must either shim the tail stock upper half to be exactly the same as the head stock, or, if the tail stock is already to high then the head stock needs to be shimmed to match the tail stock.

Dick
 
rhncue said:
You've got me a little lost here.
Click to expand...

I believe the OP is describing a situation where the tailstock spindle is not parallel with the bed ways, rather it points off to the left or right (not up or down). I am guessing that the OP testing this by running the carriage up and down the ways while indicating on the tailstock spindle. This is not a problem with the offset of the tailstock that Johns solution fixes.

The only way I can see to correct this is to rescrape the tailstock offset ridge/groove to twist the bore back to parallel with the bedways.

If you are serious about taking on this repair Mark, I'd suggest first buying "Machine Tool Reconditioning" by Edward F. Connelly.

http://www.machinetoolpublications.com/

Dave
 
I'm not going to assume anything so I have to ask.
When you set the lathe in it's current location did you level it?
If just one corner of the lathe is sitting higher or lower than the others, it can twist the ways. Even though the bed is cast iron, it can & will twist believe it or not. This will cause your tail-stock to be out of alignment with the head-stock. This will be most noticeable when the tail-stock is at the very end of the bed. If, as you move the t-stock towards the h-stock, the mis-alignment diminishes, it's an indication that the bed is tweaked. .020" mis-alignment is huge.
Before doing any alignment of the lathe you first need to be absolutely certain that the machine is DNP level. High quality machinist's levels such as Starret or Brown & Sharpe are a little pricey but are worth their weight in gold. See if you can borrow one. Once you've confirmed that the ways are level and you've still got mis-alignment then you'll have to start shimming as Dick suggested. It's not difficult to do and can be very rewarding.
The carriage ways are separate from the t-stock ways and are a different animal all together. Take it one step at a time. Oh, and good luck.
 
Good call KJ.. I assumed it was level which is the root of all fups. All good advice here.

Edit: I just re-read this. Make sure you have all of the grease / debris out of the gooves of the bottom of the tailstock.

John
 
Last edited:
kiinstructor said:
Hey Guys I need some help with aligning the tailstock of my lathe. I have an older Enco lathe that was made in taiwan I believe. Anyway I extended the barrel of the tailstock which is about 4 inches and locked it down. Then I measured it with an indicator on one end and slid it to the other and found it was off about .20.You slid what to the other end, and it's off by .20 or almost a quarter of an inch? Thats alot. It has adjustments that allow the barrell to go left and right which are simple enough to adjust but that doesnt correct a crocked barrell. Do I have to shim this? The ways are straight but I think the v grooves that the tailstock has that rides on the ways is out of line. Maybe it was machined wrong originally but Im not sure. Im considering shimming on either end to correct the misalignment but maybe there is and easier way. Your help and ideas are appreciated.

Thanks
Mark
Click to expand...
....................
 
KJ Cues said:
I'm not going to assume anything so I have to ask.
When you set the lathe in it's current location did you level it?
If just one corner of the lathe is sitting higher or lower than the others, it can twist the ways. Even though the bed is cast iron, it can & will twist believe it or not. This will cause your tail-stock to be out of alignment with the head-stock. This will be most noticeable when the tail-stock is at the very end of the bed. If, as you move the t-stock towards the h-stock, the mis-alignment diminishes, it's an indication that the bed is tweaked. .020" mis-alignment is huge.
Before doing any alignment of the lathe you first need to be absolutely certain that the machine is DNP level. High quality machinist's levels such as Starret or Brown & Sharpe are a little pricey but are worth their weight in gold. See if you can borrow one. Once you've confirmed that the ways are level and you've still got mis-alignment then you'll have to start shimming as Dick suggested. It's not difficult to do and can be very rewarding.
The carriage ways are separate from the t-stock ways and are a different animal all together. Take it one step at a time. Oh, and good luck.
Click to expand...

If your planning on doing any work more 6 inches away from the headstock, the above procedure is an absolute must.........otherwise start swimming up stream.
I will add just one more thing.....if the bed has been twisted for any extended period of time, you will have to check the level of the machine once a month for about the first year.
 
All good advise and thanks so much. Let me explain my problem again. If I lock down and extend the barrel of my tailstock and measure it from end to end, the barrel being about 4 inches, I find that it is off about .20. So the barrel of the tailstock is not true with the ways. I think I may try to shim this as Dick said. I have tried to move the tailstock to different places along the bed and take similar measurments and its the same. If I twist the tailstock a bit and lock it down the problem seem to be corrected. I think the thing may basically be worn out or the tailstock v grooves were not machined true to the way from the beginning. I wish I had some decent levels to check the bed. I have some decent carpenter levels that are about 12 inches and 18 inches but I dont think the accuracy is there. Maybe the headstock and spindle is off for all I know. I know I can put a 3/4 inch dowel pin in the chuck and it reads .0005. Hardly any movement on the indicator so maybe something is straight. Thanks again for the help.

Mark
 
kiinstructor said:
All good advise and thanks so much. Let me explain my problem again. If I lock down and extend the barrel of my tailstock and measure it from end to end, the barrel being about 4 inches, I find that it is off about .20. So the barrel of the tailstock is not true with the ways. I think I may try to shim this as Dick said. I have tried to move the tailstock to different places along the bed and take similar measurments and its the same. If I twist the tailstock a bit and lock it down the problem seem to be corrected. I think the thing may basically be worn out or the tailstock v grooves were not machined true to the way from the beginning. I wish I had some decent levels to check the bed. I have some decent carpenter levels that are about 12 inches and 18 inches but I dont think the accuracy is there. Maybe the headstock and spindle is off for all I know. I know I can put a 3/4 inch dowel pin in the chuck and it reads .0005. Hardly any movement on the indicator so maybe something is straight. Thanks again for the help.

Mark
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Any level is better then none...but something like this one is what you need for accuracy.
http://cgi.ebay.com/STARRETT-98-12-PRECISION-MACHINEST-LEVEL-NEW-UNUSED_W0QQitemZ140308155525QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item140308155525&_trksid=p3286.c0.m14&_trkparms=72%3A1546|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50

I'm still a bit confused about how and where you are measuring though.
First.....you keep saying .20.......that is 200 thou....... Is this correct or do you mean .020?
Does the barrel have sloppy movement when it's not locked down? locked down?
Sounds to me like it is just a worn out barrel based on what you have told so far. Even with a brand new rebuild you may still have to shim a bit to get it lined up but most used lathes are like that.
I doubt your ways are that far out of whack but again the machine needs to be properly leveled before you can make any accurate conclusions.
 
kiinstructor said:
All good advise and thanks so much. Let me explain my problem again. If I lock down and extend the barrel of my tailstock and measure it from end to end, the barrel being about 4 inches, I find that it is off about .20. So the barrel of the tailstock is not true with the ways. I think I may try to shim this as Dick said. I have tried to move the tailstock to different places along the bed and take similar measurments and its the same. If I twist the tailstock a bit and lock it down the problem seem to be corrected. I think the thing may basically be worn out or the tailstock v grooves were not machined true to the way from the beginning. I wish I had some decent levels to check the bed. I have some decent carpenter levels that are about 12 inches and 18 inches but I dont think the accuracy is there. Maybe the headstock and spindle is off for all I know. I know I can put a 3/4 inch dowel pin in the chuck and it reads .0005. Hardly any movement on the indicator so maybe something is straight. Thanks again for the help.

Mark
Click to expand...

If you can twist the tailstock, look on each end and see if you have a gib adjustment for the tailstock before you do anything else. I am not familiar with the enco, but most lathe tailstocks have them. They are usually a flat head screw about parallel to the ways on each end of the tailstock on the gib side. By turning them clockwise or counter clockwise, you will change the position of the gib that runs against the tailstock way. The front and back are independent so that you can adjust for the tailstock being cocked sideways.
Kenny
 
After rereading the original post, it appears that your tailstock only rides on top of the ways.
Try this. Lock down the tailstock, loosen the side to side movement screws and turn the ram while extended till it reads 0 on your dial when swept. Make sure the tailstock is locked down on the ways and run the adjustment screws back in till they touch. Check it again for true. Loosen the tailstock and move it, lock down again and re-check. If it has moved again, take the tailstock top and bottom apart and check the alignment screw boss for a gaul. If it has one, file it off and reset up the tailstock. If the screws were over tighened, they will sometimes gaul the boss and not allow for solid seating of the screws which can cause twisting when the tailstock is moved. Doing this will probably change the Center Line of the lathe between the tailstock and headstock and you will have to take cuts and retrue your centerline by moving the tailstock.

Since your tailstock rides on top of the ways, there is no standard place to shim for twisting of the tailstock. Any shims placed under the V or flat way will tilt the tailstock off the ways. You can adjust height by shimming evenly at each corner, adjust concentricity by adjusting front or back, but all will change the height of the tailstock and throw off your center line. Internally, there may be a bar and groove alignment between the 2 halves of the tailstock that you could file or mill and shim to adjust the twist movement of the tailstock, you would have to look and find out what keeps them aligned.

If the ram of the tailstock will move back and forth, then the tailstock housing should be bored and sleeved to fit the tailstock ram. This will cause it to run true without side to side movement again.
 
Thanks Kenny, I never though of those things. The tailstock sits on top of the ways as you said. MY next question is, if I loosen the side to side allen wrench screws and align the ram then tighten them back again the alignment will surely be off. How can I check check and reset the tailstock alignment at that point? Do I have to put something between centers and make a pass and indicate? Man what a can of worms but Im not gonna give up til I have it right. Im mean it not like you have to do this every time you use the lathe but its a necessity for initial setup and the lathe is worthless without accuracy.
 
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