Turning between centers

[andrewgr]

Most (but not all) of the references I've been able to find on turning between centers says to use a live center in the headstock, and a dead center in the tailstock. Some of them don't seem to specify.

I somehow (incompetence) wound up ordering things the wrong way around, so I have a dead headstock and a live tailstock.

Is this a viable setup? I won't be doing it that often-- less than once a month, I imagine-- so I don't think wear would be an issue, the way it would with a production setup. But the whole point of turning between centers is to hit tight concentricity and minimum runout, so if that's effected by which kind of center goes where, I'd like to know.

Thanks in advance!

 

[rabler]

A live center is one that has bearings so that the point turns separately from the shaft. A dead center doesn't have bearings so the mounting shaft (often a morse taper, or MT) and point turn together. You can put a spot of grease on the point of a dead center and allow the workpiece to pivot on the center's point, although at high speeds or heavy workpieces or heavy cuts, it can still overheat due to friction. A live center will have some minuscule runout due to the bearings, so a dead center has a slight advantage in that sense.

But, if you think about it, you want a dead center in the headstock, because the headstock spindle and the piece you are turning should turn together. There is no reason for a bearing there, so avoid the runout. Usually you will also use a drive dog to transfer torque so it doesn't slip/spin on the dead center. Whereas on the tailstock, it is fixed. A bearing (live center) on that end benefits.

 

[darkzero]

You may have been looking at older references, written before "live" (ball bearing revolving) centers were invented.

The way I was taught that back in the day (way before my time), a center (solid) in the headstock is called a live center because it spins with the spindle. A center (again solid) in the tailstock is called a dead center cause it does not spin. They often used white lead as a lubricant for the dead center & you have to pay attention to the tension on the tailstock as the part heats up due to friction.

But these days a "live center" is referred to as a ball bearing revolving center used in the tailstock & a "dead center" is a solid center used in the headstock.

 

[pontiac428]

Two solid centers with no bearings is all you'll need for most work. One that rotates under power is live, one that doesn't is dead. That's why a solid center in the driven spindle is "live" in the old books. I find dead tailstock centers are far better than live ones when accuracy is important.

 

[benmychree]

For best accuracy, on cylindrical grinders, both centers are "dead" and a driving plate provides the rotation.