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replacing bearings in. live center.

B

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
I hav a no name live center. I think it is not asian, seems better made then that. I see no way to take it apart. The nose cone seems to be one piece with the main body. The arbor is pressed into a ball bearing at the rear with no obvious way to pry it out. It has a small groove just outside the inner race. Not big enough for a snap ring but maybe I could get a bearing splitter in there. But what then? pushing the arbor inward would do nothing since the nose seems to be one piece with the body. And no good way to grab the body and pull the arbor out the back.
Maybe I am mistaken and the nose is supposed to rotate separate from the body. I see no snap rings, no rings to adjust bearing preload, no nothing to remove before trying to separate.
Bill D.
 
I had a cheapie live center that I replaced the bearing on. The Morse taper arbor unscrewed from the body and that exposed the bearing Inner race that could be used to press the bearing out. Perhaps the center unscrews from the body (kind of the reverse of how my live center was built)


Sent from my iPad using Tapatalk
 
The entire center rotates main body and all. just the arbor does not spin. No way to unscrew the arbor. I suppose I could try to unscrew the nose but I do not think it is a separate piece.
 
Lots of stuff like this is made to assemble-only. Typically there's a pair of matching grooves, usually with the OD groove on the shaft substantially deeper than the ID groove on the housing. A snap ring that will compress entirely into the OD groove is placed on the shaft during assembly. When the two grooves line up, the ring expands so it crosses the OD/ID boundary, irreversibly binding the shaft into the housing.

I was really pissed when I realized a rotary broach holder I bought was made that way. No way to replace bearings or do any sort of service.
 
Bill D said:
The entire center rotates main body and all. just the arbor does not spin. No way to unscrew the arbor. I suppose I could try to unscrew the nose but I do not think it is a separate piece.
Click to expand...

Clamp it well, run an abrasive chop saw carefully right down the center of the long-axis. Polish one of the split halves.

Then you will KNOW how it was put together and have become PM's Resident Expert on why this model was never worth fixing and should just be replaced.

Sacrifices just have to be made. "Pioneers" ALWAYS get arrows in their ass. That's the proof they were "Pioneers".

Just Deal With That.

NB: The ones that ARE worth fixing come from name-brand makers, US or European, mostly, have spare parts and a one or two page poop-sheet with diagram, parts list, and instructions, and can be found listed under regular rebuild services from one or several companies "in the business". Reasonable fees for what you get - EG: Tight specifications, tested, and a warranty of sorts. Just never "free".

Those folks no longer have arrows in their ass.
 
last centre i had apart was a pain they are just not made to take apart.

if i recall correctly it had a dust cover on the front where the centre part was no snap rings visible indeed no snap rings in it when its apart.
I used a hollow bit of steel and placed it over the end and wacked it down ( whole centre) on a anvil the inertia in the centre itself was enough to make it move out albeit slowly a about 15 wacks and it was out.
i.e. the centre bit that turns comes out the front or away from the morse taper end.
nothing to grab on them no punching hole from the rear.

Assembly was the easy part.

They are constantly loaded pushing the centre back no need for any retaining rings.

Once i knew how to do one i was called in to do the rest of the centres in the shop, its been a few years since i did it like about 20 thats the best i can remember of it hope it helps with the one you have.
 
Sounds like you are talking about a pipe centre. Most often they just have a pair of deep roller bearings mounted on the arbour and the cone is just pressed onto them. Most have a screw right in the nose that you can remove to access the end of the arbour to press it out.
 
gregormarwick said:
Sounds like you are talking about a pipe centre. Most often they just have a pair of deep roller bearings mounted on the arbour and the cone is just pressed onto them. Most have a screw right in the nose that you can remove to access the end of the arbour to press it out.
Click to expand...

"Most often" . there's about a hundred varieties or packagings, nose type, and tail-tapers of live centers from a dozen CURRENT makers, and easily three or four times that, orphaned, on the new and used market, any given week. That includes boxed "sets" with anywhere from two to a dozen different tips, and all-too-many worn-out, damaged, or seized-up CORPSES of live-centers.

Any of those as want to win a purchase-order, CNC world, will be NEW, also have specs for "duty", max RPM, radial and axial load, and TIR. Even if the specs include the odd lie.

No idea how accurate their claims, but here is a single "commodity market", white-bread example out of "many, many", AND NOT one of the "Grand Old" uber-precision legends:

Z Live Center - Ultimate Machine Accessories Depot

Generalities just aren't much use as to "repair" in that broad of an environment.

At least "replace" can be priced.
 
Bill D said:
That may be possible. I will have to look at it in daylight. Not a tang end may have threads in there hiden in the dirt or may just be a center drill hole.

https://www.ebay.com/itm/MT3-3MT-Live-Center-Morse-Taper-No-3/323456312916
Click to expand...

If the center in your link is similar, you'd unscrew the end cap at the front of the center (use a punch or make a wrench) and then the parts come out the front. Typically, that front cap will tighten against a split bearing sleeve to decrease the clearance of the needle bearing so you can optimize it.

If that doesn't work out, then I'd drill a hole through the back end of the morse taper until I could put something through to lightly drive it apart.
 
I seem to recall watching a YT video of a guy ramming grease and then a toilet paper slurry into a hole in the arbor of a live center with a close fitting rod to press the thing apart by hydraulic action.
 
Bill D said:
I supose if the bearings get really bad i can call it a dead center.
Bill D
Click to expand...

UN..fortunately, it is almost certain to be a very BAD one.

I harbour H&H Industrial's "not the bottom" line of Chinee ones for disposables.

Better goods? Well worth the price of a Stark or Riten, carefully put away for ONLY the times you need it and nothing less will do.

At least one PM member offers a very reasonably priced regrind service for dead centers, too. ISTR Brian Miller does that. There's a route to getting value out of a used one when your DC is big and costly (5 MT).

But don't send him garbage-metal!

Recondition one of the Grand Old legends. Their steel will be right.

Oh... and "Cimcool" it. Pink slime. A little dab'l do yah.

Makes slickery Owl shit look like concrete by comparison.
 
HuFlungDung said:
If the center in your link is similar, you'd unscrew the end cap at the front of the center (use a punch or make a wrench) and then the parts come out the front. Typically, that front cap will tighten against a split bearing sleeve to decrease the clearance of the needle bearing so you can optimize it.

If that doesn't work out, then I'd drill a hole through the back end of the morse taper until I could put something through to lightly drive it apart.
Click to expand...

Are you saying unscrew the cone? I think the body is one piece but I can try some pipe wrenches on it. It IS the one in the link. I thought it was worth $10
Bill D
 
You got just what you paid for, the description says bearing is rough. Throw it in the junk and go buy a good one.
 
Bill D said:
It IS the one in the link. I thought it was worth $10
Click to expand...

No foul.

If you thought that, then to you it WAS worth $10. ipse dixit

The lathe has other ideas?

Kick the insubordinate bugger right square in the half-nuts, sort the medical bills from landing on your tail-bone high-kicking.

When you are able to hobble back into the shop, award that round to the lathe on "points", and go buy it a new live center as its prize for winning the fight.

It BEAT you, fair and "within TIR!"

:D

Machine tools are like wimmin. They "want what they want when they want it."

You being stuck with "you'll get what I got when I get it" is just the price you pay for being able to write yer name in the snow with a stream of piss.

EG: Nought but pissing about for starters, and not always the better deal as to outcomes, if even anyone else gives damn.

:D
 
a rotary broach holder I bought was made that way
Click to expand...

Well, being's how rotary broach holders are so cheap to buy, why not? (Just kidding, I always wondered if they put a litle gold bar inside those things!)

Throw it in the junk and go buy a good one.
Click to expand...

I found one spindle thing like that, not sure what it was but it had knurled OD areas chamfered down to straight turned areas. When I tore it apart to satisfy my curiosity about it I found there was a seam where the chamfer stopped, and it unscrewed there. Normally one can see the assembly line but not that one.
So if you chuck it why not do an autopsy first so we'll know?
 
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