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Suitable live center for a small bore 13?

Just a Sparky

Just a Sparky

Hot Rolled
Joined
May 2, 2020
Location
Minnesota
Looking at page 17 of this brochure, I note the spindle taper is listed as #3 morse. This catalog is from the days *after* they switched to the double tumbler quick-change gearbox and large bore spindle if I'm not mistaken. I'd like to know if my 1946 small bore has the same #3 morse taper or if they changed that. I'd like to pick up a live center for the spindle so I can turn between centers.
 
Just a Sparky said:
Looking at page 17 of this brochure, I note the spindle taper is listed as #3 morse. This catalog is from the days *after* they switched to the double tumbler quick-change gearbox and large bore spindle if I'm not mistaken. I'd like to know if my 1946 small bore has the same #3 morse taper or if they changed that. I'd like to pick up a live center for the spindle so I can turn between centers.
Click to expand...

You already HAVE the lathe within your reach ... and you are asking those CANNOT reach out and touch it?

Just go and look.

:)

You don't need - or even WANT - a "live" center in the spindle. They are for the tailstock. 2 MT, usually. Ten bucks for a Chinese "dead" center? They work OK. Spend more for a Stark or Riten when you know more.

Import "live centers", same again. The cheap ones are. Cheap.
The good ones are NOT cheap. Skoda is value for money. Riten is worth their premium price. IF you have the need for top-grade and long-lived.

You can turn between centers "real, soon , NOW!" by MAKING a center at the headstock/spindle end on a short length of stock gripped in any chuck or collet you already have.

As it turns WITH the work, some modest pressure is applied, but no sliding friction, so it need not even be hardened.

TS dead center. OTOH, should be seriously hard. Several of my "working" ones are Carbide tipped. Some very finely finished all-steel ones are NEVER used for turning. They are kept safely put away and used only for measuring & alignment.

A store-bought or shop-fab "driver dog" can have it's tail rest against a chuck jaw and you are "in bizness" rapidly & cheaply.

Light lathes, SB especially, are generally just fine with "dead" centers at the TS. I also recommend a squeeze-tube of "pink slime" AKA CimCool "center saver" for lubing a dead center. Nothing is perfect, but it IS "closer than most".

:)

Live centre "kit" wih multiple tips that cover pipe, tubing, and such CAN be handy as much for that variety as for having roller bearings. Start cheap. You probably won't even use it often, and even then, if you invest in BETTER goods, later, the El Cheapo is still there for less demanding or riskier setups or tasking where you might want to modify something.

2CW
 
thermite said:
You already HAVE the lathe within your reach ... and you are asking those CANNOT reach out and touch it?

Just go and look.

:)

You don't need - or even WANT - a "live" center in the spindle. They are for the tailstock. 2 MT, usually. Ten bucks for a Chinese "dead" center? They work OK. Spend more for a Stark or Riten when you know more.

Import "live centers", same again. The cheap ones are. Cheap.
The good ones are NOT cheap. Skoda is value for money. Riten is worth their premium price. IF you have the need for top-grade and long-lived.

You can turn between centers "real, soon , NOW!" by MAKING a center at the headstock/spindle end on a short length of stock gripped in any chuck or collet you already have.

As it turns WITH the work, some modest pressure is applied, but no sliding friction, so it need not even be hardened.

TS dead center. OTOH, should be seriously hard. Several of my "working" ones are Carbide tipped. Some very finely finished all-steel ones are NEVER used for turning. They are kept safely put away and used only for measuring & alignment.

A store-bought or shop-fab "driver dog" can have it's tail rest against a chuck jaw and you are "in bizness" rapidly & cheaply.

Light lathes, SB especially, are generally just fine with "dead" centers at the TS. I also recommend a squeeze-tube of "pink slime" AKA CimCool "center saver" for lubing a dead center. Nothing is perfect, but it IS "closer than most".

:)

Live centre "kit" wih multiple tips that cover pipe, tubing, and such CAN be handy as much for that variety as for having roller bearings. Start cheap. You probably won't even use it often, and even then, if you invest in BETTER goods, later, the El Cheapo is still there for less demanding or riskier setups or tasking where you might want to modify something.

2CW
Click to expand...

A true live center in the traditional sense, as in a rotating solid center affixed to the spindle, rather than a so-called "live" ball/roller-bearing dead center as would be inserted into the tailstock.

Yes, I have the machine within my reach but I am still tooling it up at the tail end of a rescue and rebuild. Still waiting for it's flat belt to arrive on Friday in fact. I'm not sure how I would go about measuring the taper of the spindle given I don't happen to have a set of taper gauges or inside calipers lying around. Given how many of these machines are still around and how often they are rebuilt I figured someone in the know could point me in the right direction in all of about five seconds.

I've got a full set of original dogs, shims and faceplates. Just need the right center for the spindle taper.
 
Just a Sparky said:
A true live center in the traditional sense, as in a rotating solid center affixed to the spindle, rather than a so-called "live" ball/roller-bearing dead center as would be inserted into the tailstock.

Yes, I have the machine within my reach - but I am still tooling it up at the tail end of a rescue and rebuild. Still waiting for it's flat belt to arrive on Friday in fact. I'm not sure how I would go about measuring the taper of the spindle given I don;t happen to have a set of taper gauges just lying around. Given how many of these machines are still around and how often they are rebuilt I figured someone in the know could point me in the right direction in all of about five seconds.

I've got a full set of original dogs, shims and faceplates. Just need the right center for the spindle taper.
Click to expand...

..or point you in the WRONG direction in "all of about five seconds", since you HAVE the lathe and they have information that MIGHT not match your one. SB had lots of options, new. Rebuilds and alterations have happened since new.

I don't THINk I am anybody "special" to be able to tell #1, #2 , #3, #4, #5 MT by EYE.. from half-way across the room? Besides, what with MT drills & sleeves, I have PLENTY of every one of them, so all I have to do is grab one to confirm.

Your only challenge on a(ny) lathe HS spindle taper is that USUALLY they are made with only a partial SECTION out of a larger taper.

And not all makers use the same "chunk" w/r the reference line.

So you get the front, middle, or back PORTION OF a 4 or 5 MT.. or a portion of the #12 jarno on a 10EE, portion of 5 MT on a Cazeneuve, etc.

Nearly all lathes but the tiniest (@las 6" X 18" LSO was native #2 MT HS, #1 MT TS) had an adaptor from the bore taper down to a # 3 or #2 MT .. partly so the stick-out was less by an inch or two.

MT sleeves are a cheap way to check. Nice newly made ones and a bit of blue can also help you find and stone-off burrs in a tapered bore or reveal serious wear.

Also handy for adapting TS drills & c..

Good to have a few around, regardless. Order a couple. Then you'll be able to tell in "all of five seconds", for-real.
 
So what I'm gathering is that South Bend published their literature describing the 13s as taking dual 3MT centers despite the spindle being bored for 4MT since the machines were supplied with a 4MT to 3MT adapter?

In hindsight I just remembered I've got the collet kit lying around since mine is the toolroom model. Let me go measure the outside of the closer. That doesn't require special tools. :rolleyes5:

EDIT:

So I came back with the following figures:
Major diameter = 1.230"
Minor diameter = 1.131"
Taper length = 1.875"

Crunching the numbers yields a taper per foot of 0.0502.

So it's a #3 MT extrapolated to a #4 MT's major diameter. Technically SB's literature is correct... but good luck finding a #3MT center that large.

What a pain in the ass.

A 4MT adapter/center will probably be good enough since we're only talking about 3.1875 thousandths (A literal hair's breadth) of slop at the inboard end.

EDIT EDIT:

This spec sheet says the small bore 13 is supposed to have a 4MT taper spindle and should accept 4MT tooling natively:
http://www.wswells.com/data/spec_sheet/5224.pdf

In light of that, why my collet adapter is an oversized 3MT is beyond me.
 
Just a Sparky said:
So what I'm gathering is that South Bend published their literature describing the 13s as taking dual 3MT centers despite the spindle being bored for 4MT since the machines were supplied with a 4MT to 3MT adapter?

In hindsight I just remembered I've got the collet kit lying around since mine is the toolroom model. Let me go measure the outside of the closer. That doesn't require special tools. :rolleyes5:

EDIT:

So I came back with the following figures:
Major diameter = 1.230"
Minor diameter = 1.131"
Taper length = 1.875"

Crunching the numbers yields a taper per foot of 0.0502.

So it's a #3 MT extrapolated to a #4 MT's major diameter. Technically SB's literature is correct... but good luck finding a #3MT center that large.

What a pain in the ass.

A 4MT adapter/center will probably be good enough since we're only talking about 3.1875 thousandths (A literal hair's breadth) of slop at the inboard end.

EDIT EDIT:

This spec sheet says the small bore 13 is supposed to have a 4MT taper spindle and should accept 4MT tooling natively:
http://www.wswells.com/data/spec_sheet/5224.pdf

In light of that, why my collet adapter is an oversized 3MT is beyond me.
Click to expand...

"It is whatever it is." You can adapt to it easily, or re-engineer it the hard way.

Basically.. the makers made compromises to get best all-around balance between maximizing utility of available spindle bore and minimizing stick-out that ate "daylight", needed longer "tails" on driving dogs, and could reduce stiffness.

As-shipped.. WITH the adapters that fit, it was no big deal.

Only ages later, OEM adapters gone walkabout, does it become a nuisance or a puzzle.

More than a few among just make what they need. Have to.

SB is common enough, you might be able to just buy.
 
Just a Sparky said:
So what I'm gathering is that South Bend published their literature describing the 13s as taking dual 3MT centers despite the spindle being bored for 4MT since the machines were supplied with a 4MT to 3MT adapter?
Click to expand...

The "dual MT#3" centers includes the spindle adapter for the headstock (and assuming that your adapter is an MT#3 model).

Just a Sparky said:
So I came back with the following figures:
Major diameter = 1.230"
Minor diameter = 1.131"
Taper length = 1.875"

Crunching the numbers yields a taper per foot of 0.0502.
Click to expand...

Well, crunching YOUR numbers, I came out with a taper per INCH of 0.0528", which means that it is a NATIVE MT#4 taper spindle (but short, so it is NOT a true MT#4).

Just a Sparky said:
So it's a #3 MT extrapolated to a #4 MT's major diameter. Technically SB's literature is correct... but good luck finding a #3MT center that large.

What a pain in the ass.

A 4MT adapter/center will probably be good enough since we're only talking about 3.1875 thousandths (A literal hair's breadth) of slop at the inboard end.

This spec sheet says the small bore 13 is supposed to have a 4MT taper spindle and should accept 4MT tooling natively:
Click to expand...


None of this is relevant or true, since you calculated wrong.

Just a Sparky said:
In light of that, why my collet adapter is an oversized 3MT is beyond me.
Click to expand...

That's just the way South Bend did it. Anyway, it looks like your collet adapter isn't an oversized MT#3, but a native MT#4.

Just a Sparky said:
A 4MT adapter/center will probably be good enough since we're only talking about 3.1875 thousandths (A literal hair's breadth) of slop at the inboard end.
Click to expand...

If this WAS correct, it WOULDN'T be good enough, unless you were happy with a significant amount of runout on whatever you mounted in your collets.

Also, since your spindle is a SHORT MT#4, if you get a true MT#4 to MT#3 adapter, you'll have to cut the small end down to the correct length, since it may be too long for your spindle.

You have a tool room model, which means you have a taper attachment installed, so why don't you make your own center?
 
Damn guys, ease off.
I have a small spindle 13. MT4 fits fine in the headstock, 3 in the tail. Cutting off the end of the 4 is of no help, it sticks out of the spindle to the right what I considered too far. SO I bought an adapter from ??? Machine that makes such things. Stuck the adapter in the spindle, stuck a 3 in it, stuck out just about as far.
Consider that the taper just blends into the 1" bore. The center could be long enough to come to a point at the left end and it would not make any difference.

And yes, like OP says, in days of yore, a solid pointy thing sticking out of the headstock was called a live center because it would spin when you moved the shipper to get the lathe spinning.
 
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