Live centers, do we need them?

Have a machining book here that refers to the moving headstock, what we refer to today as the tailstock.

In the book "Technology of Machine Tools" by Krar, Oswald & St. Amand, which is the text book of choice for most of the trade colleges that I have seen, it refers to the live centre as the centre that is mounted in the headstock, and is under powered rotation, and talks about how to seat it, check it for trueness and grind it true if needed. Also deals with how to remove it with a knock out bar. Units 44 and 45

The dead centre is the one which is mounted in the tailstock, or the one which is not under power.

As I mentioned before, the ball bearing dead centre has become known as a live centre, and advertised as such until now it is only known as that.

But, that now brings a question "eschew obsification" (avoid confusion) when you set up to turn between centres, which one is the live centre and how can there be a live centre at each end?


Mayhem, you can call them any thing you like. George is just fine.

Guys this is just a point of semantics, A rose by any other name is still a rose, I was taught by my instructor in school that if you refer to a tool by its proper name, then there will be no confusion as to what you are refering to. Here we have a case where the knick name actualls leads to confusion.

Walter
 
starlight_tools said:
But, that now brings a question "eschew obsification" (avoid confusion) when you set up to turn between centres, which one is the live centre and how can there be a live centre at each end?

Walter
Click to expand...

Wouldn't that be a headstock live centre and a tailstock live centre (or tailstock ball bearing live centre)
The way there would be a live centre each end is because the headstock one rotates with the spindle on it's bearings, and the tailstock one rotates by the job on it's own bearings, so both are live and spinning, unlike a tailstock dead centre.

I understand where your coming from, but as you said, everybody recognizes a tailstock ball bearing live centre as a tailstock live centre these days. So you would be on your own to call it something else, and other people may not understand what you where talking about.

Dave
 
I thought it would be fun, so I made my own 60* long & short, med. & large bull nose/ or should I say my SB 9A
made them for me. Probably many will not aggree, but they were made out of brass which is quick and easy.
I use Ford fan belt idler bearings cheap at Napa and seem to be just right. They work fine because you do not over
kill with them just enought pressure so it spins.
 
GK1918 said:
I thought it would be fun, so I made my own 60* long & short, med. & large bull nose/ or should I say my SB 9A
made them for me. Probably many will not aggree, but they were made out of brass which is quick and easy.
I use Ford fan belt idler bearings cheap at Napa and seem to be just right. They work fine because you do not over
kill with them just enought pressure so it spins.
Click to expand...

They sound nice, did you polish them up or just leave them as machined?
Some pictures would be nice if you have time.

Dave
 
Davo J said:
...

I understand where your coming from, but as you said, everybody recognizes a tailstock ball bearing live centre as a tailstock live centre these days. So you would be on your own to call it something else, and other people may not understand what you where talking about.

Dave
Click to expand...

Dave, how correct you are!

At one time you could call a bundle of sticks by its proper name, now you are being homophobic.

There are many terms that over the years have been used incorrectly and the incorrect meaning has stuck and become the accepted term. This is one of them.

But then how many times is stock turned between centres anymore?

As to the OP request, whatever you want to call the ruddy little thing, we had one nomination for George so far, yup it is one of the best investments you will make in your lathes tool kit.

Walter
 
I've been using ball bearing centers for over 30 years. My first one WAS the one Sears used to sell.
 
I guess that someone needs to inform Enco that it is incorrect to call their ball bearing center a live center ;^)

BTW: What do you call a center that has roller bearings inside ???

Randy
 
Bill Gruby said:
It is what it is and thats all it is, yes you need one.

I wouldn't try calling a bundle of sticks that name today. :lmao::lmao::lmao::lmao::lmao::lmao:

"Bill Gruby" :thumbzup::thumbzup:
Click to expand...

Yup and you really have to be careful what you call a cigarette as well.

Hope, I did not tread on anybodies toes with this, it was meant to be informative and fun at the same time, pointing out what has happened over the years to "proper" terminology and how what is at some point mis-stated becomes the now accepted term.

Walter
 
I do a lot of small work. For the small stuff,I got one of those little Royal roller bearing centers where the center shaft goes inside the #2 MT shaft. It has a long CNC type tip. It wasn't real cheap,but I don't have trouble with the tool holder wanting to hit the bearing housing that the usual type of centers have. I use it in my HLVH,which has a #2 MT tailstock. My larger lathe has a #4.
 
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