Live center accuracy, what's acceptable

[Tony Wells]

I remember when a "live" center was the one in the headstock spindle, and supported work turned between centers, and the "dead" one didn't rotate and was found in the tailstock.

 

[refinery Mike]

Yea you are right tony, it has been a long time! And my memory is not the greatest!

 

[Ray C]

Hi Mike / All...

I don't know if all centers work this way but my cheapo brand (3 of them, one really small, one medium and one medium w/long nose) have a screw at the end of the taper to oil the bearings. I throw a squirt of oil in there once in a while and all are working fine as far as I can tell.

Ray

I like the live center because i do not have to worry about getting some swarf in the greese. then when you put it back in the lathe it chews up your work and your center. (Been there done that) But runout is not the only thing to think about when buying a live center. The cheep Chinese live centers may only last a year and then get so loose the bit chatters like crazy. (Been there done that). Might be better to go for a middle of the road live center, for a hobby lathe. Does anyone else remember when a live center was a plain center that was actually hardened, and a dead center was left soft. (for the head stock)

 

[The Liberal Arts Garage]

i was taught the old way with a dead center and a tube of the yellow and black from Mc Master Carr.
i don't think i've used a live center more than a handful of times, but then again most of my tolerances just have to be to .010"
it just doesn't seem practical to buy a cheap live on sale, when an not so expensive dead will produce equal results in my opinion.
buy a good live if you're serious about your working tolerances, otherwise it might be a good lesson to learn how to use a dead center.
the old timers figured out how to do a lot things with very little at their disposal in relativity to today's ease of availability.
today's machinists have more sophisticated tools,and amazing.
but ,i fear a lot of the old ways are being lost to time. ease takes over, not many can do things the (old) hard way if necessary.
i hope we all can keep the spirit of the old timers ,that we all share to some degree.
to do difficult, intricate things because we can!!!!
Cheers

This may be a good time to mention a physics / math / chem. teacher who could be quite
angry with students who implied accuracy beyond the supplied numbers or measurements. Sometimes a bit o/s and some diamond paper is th best fit. I used to mix anti- sieze with a few
drops of heavy oil for dead centers......BLJHB

 

[xalky]

I have some older live centers that, if pushed a little hard, will flex, .001 to.002. I don't throw them out, I use them when I'm hogging, taking heavy cuts. Why stress the good ones! When I get towards the final 2 lighter cuts I'll change the worn one with the new one. I do use a dead center in the tail stock occasionally, but it's a fine line between not tight enough, and to much heat. I only use a dead center in the tail, when I can't get close enough with the cutter because of live center diameter being too large.