when do you use a live center instead of a dead center?

Another note on solid centers; The center that is used in the headstock has a vee slot turned in the shank on the taper that fits the spindle taper, this is to signify that it is soft at the point; this is so that it may be trued up by re-cutting if it runs out. The tailstock center is hardened and has no such slot and must be ground to true it up, although carbide tools of a harder grade, such as Kennametal K-6 will cut most hard parts.
 
Ken from ontario said:
I've been asking myself this question for a while and don't exactly know at what point does one need to move from a dead center to a live center?
Is it because with a live center you can put more pressure to the center of the workpiece and therefore cut more precisely? or does it have something to do with the size of the workpiece?
If you use a well lubed dead center and there's no sign of the tip overheating, why would you use a live center than?
could you explain that for me.
Does the live center always go in the headstock?
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As noted, we recently had this same discussion. I will repeat what I said there. The nomenclature and the associated meanings of the terms "live" and "dead" centers have become so hopelessly convoluted over time that I will only say "solid" and "ball bearing" to describe types of centers -- at least in public discourse. Call it anything you want if you are only talking to yourself...
 
If you Ck textbooks any center used in a head stock is live , in the tailstock it's called dead. Just to use the official teaching method. So a ball bearing center we call live really isn't unless you put it in the head stock. I always thought it was bassakwards. But I try to say it the right way.
 
Use a rotating center when running a spindle speed that is entirely too fast for a non rotating tool, the difference will become obvious with time (-:
 
I think that may well be the best approach, but to be a little factious, when we cylindrical grind, generally on dead centers, we have the option of running the headstock center either stationary or rotating; live or dead ??????????? Personally, I think the live center is of the anti friction bearing type, and dead centers are of the solid type, whether they rotate or not
 
We also keep the center in the headstock still and only have the face plate driving the dog. Makes a better grind.
Pierre
 
pdentrem said:
We also keep the center in the headstock still and only have the face plate driving the dog. Makes a better grind.
Pierre
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Yes, I have always done so, personally, it is the correct way to do the operation, but my point was that the same article could be describe as being both live and dead in the same spindle. Personally I think that this whole discussion has been a bit on the silly side; as far as modern usage has it, I think both centers are dead if they are solid, but perhaps we just need to stop splitting hairs and just say "turning on centers".
 
In doing a bit of research, dead, live, rotating etc etc has regional, country and cultural variances. I look at it as - if driven it is live, stationary - dead, and rotating means with some sort of bearing. This is how I explained it to the new guys even if they just came out of school/apprenticeship that way we are all on the same page. Any confusion can lead to errors and scrap parts or rework.
Pierre
 
Thank you all for your opinions and inputs, I read all of your comments with a lot of interest but mainly to clarify the usage of centers, which means , under what situations do I reach for a "solid" center or "ball bearing" center .
I got the answer to my question (and the majority of you agreed )with post #5 and #6, although it was really interesting to read all the rest of your comments about the reasons why they are called live or dead centers and where it originated from .I learned a lot from all your opinions .
Again thank you all .
Ulma Doctor said:
with dead centers, the will produce work with less runout than a live center-
.
i still use dead centers when turning between centers or when threading
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mikey said:
Nowadays, most of us use live centers for almost all work and yes, a live center goes into the tailstock.

As mentioned, a live center is usually used most of the time because it does not require us to stop the lathe and lube the tip of this center.

So, when is a dead center used? It is most often used when we want the ultimate in accuracy, either to turn a precision work piece "between centers" or when using a test bar to align a tailstock. Otherwise, most of us just use a live center.
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