centering tailstock

[porthos]

going to use the two collar method to center the tailstock on my heavy 10. can i use a collet in the spindle instead of a lathe dog and faceplate. and dead center in the tailatock. or, is it necessary to turn the collars between centers

 

[benmychree]

The latter would be best.

 

[Bob Korves]

The collet will introduce inaccuracies that turning between accurate centers will not. The collet might be a more robust setup for heavier work that does not need extreme accuracy, depending on the details. For finishing the two collars, you want maximum accuracy, and the loading is light. Turn between centers if possible.

 

[porthos]

i guess i'll turn between centers. thanks

 

[agfrvf]

I like the method of holding thin flat stock square between two centers.

 

[Technical Ted]

If you don't have a center and faceplate for your lathe, you can turn a 60 degree point on a piece of stock held in either a 3-jaw or 4-jaw chuck and use that for a center at the head stock end. The lathe dog can be driven against one of the chuck jaws. I've used this method a lot and it works great.

Ted

 

[woodchucker]

I like the method of holding thin flat stock square between two centers.

How do you prevent it from bowing if it's thin? And how do you know how accurate it has been center drilled?

 

[dpb]

As long as you don't get aggressive, aluminum can be turned between centers without using a dog. You can cut a center on stock held in your chuck, and then hold the aluminum between that and your tailstock center, with firm pressure.

 

[RJSakowski]

Another method for aligning the tailstock would be a modification of Rollie's Dad's Method. A round bar mounted between the headstock and tailstock centers. An indicator mounted on the cross slide or compound. The minimum and maximum readings are recorded at the headstock and the carriage is moved to the tailstock position without changing the cross feed or compound setting. Maximum and minimum readings are recorded. The difference between the averages at those two positions will be the tailstock offset. The bar needn't be mounted on a headstock center. The requirement is that the bar rotate with the spindle.

I checked my tailstock by grasping the bar at the first serration of my 3 jaw chuck. My readings were+.0021" and -.0021" at the chuck and +.0005" and -.0007". The average at the chuck was .0000" and at the tailstock, -.0001" with a difference of .0001". I would have to move my tailstock .0001" to the front to zero.

Requirements for this method are that the bar be round and ideally the same diameter at either end. It doesn't matter if the bar is straight or if the center drills are concentric with the bar. This method can measure both horizontal and vertical misalignment depending upon how the indicator is set up. It can also be used to accurately set taper if the distance between the measurement points is known. No turning is required which means faster alignment.

 

[projectnut]

If you offset the tailstock on a regular basis I would suggest investing in a test bar. I was offsetting the tailstock on my Sheldon several times a week. It got to be a pain to realign it every other day so I invested in a test bar like this:

http://www.penntoolco.com/edge-tailstock-alignment-bar/

If it's a one time adjustment I would also turn between centers. Make sure you true the center in the headstock before taking any cuts on your stock