Shopping for a Live Center?

Just in case you run into a fussy old fart, like me , be aware that the traditional meaning of a "live center" is one that is driven under power. In other words, a headstock center.

A ball-bearing center for use in the tailstock is a ball-bearing dead center.

You won't have any problem using the term the way you're using it, unless you get an old guy on a bad day. d8-)

"Ed Huntress" wrote in news:4bf05125$0$4995$ snipped-for-privacy@cv.net:

Well, it now gets more complicated. For the project at hand, I will be applying pressure with the "ball bearing dead center" to clamp the work. I was thinking that some sort of spring would be good. Lo and behold, they also make spring loaded "ball bearing dead centers". That sounds like just the ticket, and it simplifies the shopping problem considerably. Riten & Royal make them, and there's not much difference in price, but the Royal specs & design look a little better.

Doug White

I've always heard of the bearing center called live and a solid center called dead.

But when a solid center is in the headstock, it is indeed live as in rotating with its support and solid centers with lubrication have been used in the tailstock that is a fixed support.

Bored Ed?

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

The spring loaded function is quite handy when turning long relative to diameter stock. As you remove stock, the work expands and when supported by something un-giving, has to deflect to relieve the stress. The spring loading, properly used, minimizes the effect.

Of course, you can just check tail stock pressure each pass if you don't have the spring.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

iameter stock. As

mizes the effect.

have the spring.

Then again it gives if you cut towards it. I bought an inexpensive Enco ball bearing center and switch to a dead center for the finishing cut.

A ball bearing pipe center can be handy if you turn tubing.

jsw

Then you aren't old enough. Or you didn't steep yourself in old machining books for a decade or two.

A live center is powered. A non-powered center is dead. If it has a plain bearing (some did), it's a plain-bearing dead center. If it has ball bearings, it's a ball-bearing dead center. Of course, if it has no bearing except for the center cone, it's just a plain dead center.

Like many things in machining, the original meanings have gotten lost from common useage. But that's the way it always was, and I think most machinists used the terms that way, at least into the '60s.

Nope. I had a great day catching bluefish across from Staten Island.

There are other old machining terms that have gotten lost or corrupted. I used to keep track of them, and I'd often comment on them, with the old meaning and the new, in articles I wrote for _American Machinist_. I've forgotten the rest of them.

While it's on my mind, though, the machine is a jig borer, not a jig bore. And a lathe with no saddle, cross-slide, or tailstock is a speed lathe. A short-bed lathe with no tailstock is a chucker. A measuring tool is spelled "gage," not "gauge," based on a precedent set by _AM_ back in the

1870s.

My wife considers me to be a specialist in boring machines, and other boring things.

Doug White wrote in news:Xns9D7A9F272F0D9gwhitealummitedu@69.16.186.50:

I have been satisfied with the Czeck made Skoda center I purchased 15 years ago. Reasonably priced and repair parts are available, seems like they stand by their product instead of being part of the toss it and buy new economy. I wouldn't mess with a spring loaded center unless you know the spring rate will provide adequate holding force for your application.

Ed,

Relax and go out fishing, The striped bass are running big time.

John

Fishing from shore, you can hardly get a bait down through the blues to get at the stripers. I've given up on them, and I'm in no mood to go out in a boat.

But we're catching a lot of blues at the Cliffwood Rock Wall, just above Keyport.

Ed,

I should have taken a ride to the shore and wet some bait.

John

There's not much action on the surface yet, John. It's bait fishing on or near the bottom. Most of us are using chunked bunkers. Stripers are hitting bunkers, too. They prefer the heads. Or use clams.

If you try the west end of Raritan Bay, the fish are there from about an hour or two before high tide to an hour or two after it. It's a fish every

15 minutes or so, and they're running from 2 pounds up to around 10. Bigger ones are being caught out in the Bay, up to 18 pounds.

Stripers are still being caught on the west end, but I think most of the striper action is out around the Highlands and up along Sandy Hook.

Charles U Farley wrote in news:gV_Hn.8108$ snipped-for-privacy@newsfe21.iad:

I've heard of Skoda, but they don't seem to be popular with the major distributors these days. MSC, Penn, & Enco don't carry them. Wholesale Tool has them, and they seem very reasonably priced, but they don't have any TIR specs. I couldn't find TIR specs on any Skoda centers in a half dozen web sites. Even Bison Chinese centers at least have a TIR spec of

0.0001".

Doug White

"Ed Huntress" wrote in news:4bf074a9$0$31278$ snipped-for-privacy@cv.net:

To paraphrase Monty Python: They're not dead, they're just restin'...

Doug White

It's not likely that any HSM needs a tailstock center with a guaranteed accuracy of 0.00005".

It's also not likely that a tailstock is adjusted to that accuracy. A tailstock's center axis deviates considerably more than that every time it's moved, or ambient temperatures change.

Furthermore, it's highly unlikely that any HSM's parts need to be made to that accuracy, or that the HSM would need to accurately measure parts to that accuracy.

Anyone that's trying to accomplish these levels of accuracy in tooling is chasing a rainbow. One could buy 10 reasonably priced, quality centers and keep 2 or 3 that are most accurate, return the others. An accurate measuring setup could be assembled on a surface plate instead of actually using the parts.

The pressure applied by the tailstock can be monitored, if you like the prices of a center with an integral pressure gauge. Rohm is one brand, but you may have trouble finding a model in the MT 2 size.

k that is a fixed

If you want to find a center with bearings in a catalog, you had best look for live centers. I do not think you will find " ball bearing dead centers " listed in any catalogs. But there was a time when Ed's terminology was used. But probably not in the last fifty years.

Dan

Everything with a cutting edge (and many other small items) has become a Bit.

A portable saw with a circular blade becomes a skill saw.

Small portable saws with a reciprocating blade become a jig saw.

A utility knife becomes a box cutter.

Corded or cordless drills become screwguns.

Summer tires become all-season tires.

What a bunch-a-shit.

On Mon, 17 May 2010 00:39:38 GMT, Doug White wrote the following:

Hmmmmmm, ahem, mi mi mi. Alright, then.

"Oi'm a Lumberjack and I'm OK..."

-- Work and struggle and never accept an evil that you can change. -- Andre Gide

For the project you asked about I don't think the cheap one will give you any fits. Any wobble it does have can be quelled with a little rubber* but you probably don't even need to worry about that.

MSC has a "value" cheapie for about $20, and since you have gone several years without needing one at all you probably won't get that much use out of a super expensive one to justify the bigger price.

This would also give you a balance of $180 to spend on other tools.

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then they come up with this striped stuff.

• A rubber washer or a piece of sheet rubber placed between the plastic and the plate will allow a bit of wobble in the live center but the part will still be concentric with the indexing pin in the driven side of the equation. All the pusher plate does is hold the blank against the driven mandrel with enough force to keep it from slipping while you cut. Given the light cuts you will be taking for this project it will not require that much pressure.