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

Ken from ontario

Ken from ontario

H-M Supporter - Silver Member
H-M Supporter - Silver Member
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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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The live center goes only in the tailstock.
In My Opinion"
Live centers are good enough for anything I do on my lathe. Granted it's a small lathe, and I don't have many demanding jobs.
Dead centers, I'd use in a cylinder grinder. (anything round) There's little pressure (comparatively) on the center.

Time was.... before the development of dependable live centers... that dead centers were all that there were.
 
Interesting question. The dead center was first to happen and then I guess someone came up with the live center idea because of some of the dead center pitfalls. Nowadays IMHO, if you can afford/justify a good live center then get it. Maybe also get a dead center just because.
 
i was taught to work with dead centers, they will produce work with less runout than a live center-
although the tolerances on live centers now is near enough to make them very accurate and suitable for most work any of us will ever do.
i still use dead centers when turning between centers or when threading
 
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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?
Click to expand...

Nowadays, most of us use live centers for almost all work and yes, a live center goes into the tailstock. There was a discussion not long ago about the nomenclature of dead centers and supposedly the solid centers that go into the headstock are "live" centers and the ones that go in the tailstock are "dead" centers. While interesting, the reality is that most of us use tailstock centers with bearings inside them and we call them Live Centers.

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. When using a dead center, you have to stop the lathe from time to time to re-lube the tip of the center and then readjust the tailstock pressure because the work piece will heat up and expand from friction between the dead center and work piece.

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.

Not all live centers are created equal. I use a Royal live center and it is very precise, with no discernable play. Cheap live centers can have enough play to affect accuracy, especially when turning big, heavy work pieces so buy a decent one.

Hope that helps.
 
Rotating centers only go in the tailstock as stated earlier. Dead center can go in the spindle or the tail stock.

One advantage to using dead centers is you can make a custom one fairly easily. Once it is cut and ground in the spindle it is accurate while a rotating center is dependent on the quality of the bearings and the other components. I also only use dead centers in our Landis Cylindrical grinder they are the most accurate. We need to be inside of 0.0002" in roundness and when making match sets of rolls for rolling mills, dead centers are the only way to get this kind of accuracy.

At home, I have used both with varying success. My rotating center is only a mid grade, maybe 0.002" but I questioned that ever since I had it. Never checked as I never had a home job to be that good. Only $200 vs a lot more for a real nice one. YMMV
Pierre
 
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Spend the extra $$$ and get a nice name brand live center to use.

I recently bought one of those cheaper $30 live centers to put with the 13" lathe I sold. What a joke! I could flex the center up and down enough you could see the movement. Of course, put a load on it and I couldn't get it to move. I don't get that with my other German made live centers I have.
 
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