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Spindle Morse Adapter...or no?

Splat

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#1
So talking to a guy at work the other day I found out he's a home hobby machinist. He just picked up some Asian lathe, whose name escapes me att. He said he wanted to get an MT5 dead center for it. I suggested since he's already got MT3 dead center to just get a MT5/MT3 spindle adapter since he's already got other MT3 tooling. So we talked about that for a while and he then said "Yeah, but the MT5 center should be more accurate." Now guys, this may be true but I don't think a well made adapter should provide that much runout to make a difference compared to an MT5 center that fits the spindle taper, no? The only difference I could think would be ability to hold heavier workpieces in the MT5 dead center, compared to an MT3 in spindle adapter. Am I missing something here?
 

rgray

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#2
My lathe came with the 5-3 adapter. I eventually bought an mt5 with a carbide tip anyway.
I'm sure I didn't need it, but it's nice.
The thought of eliminating one surface of possible error.
But with the two pieces the possibility of indexing them to eliminate error is something that could not be
accomplished with a one piece.
I have not indicated either to verify. But when I work between centers everything comes out accurate.
(good enough for me anyway)and that's not sayin much
 

Bob Korves

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#3
Either will work. Accuracy is dependent on the runout of the lathe AND the tooling. Perfect work on a perfect #5 or perfect work on a perfect #3 in a perfect 3-5 sleeve would be equal. Since our world, and our machines, and our tooling are NOT perfect, it gets more interesting. If you have a spindle taper on your lathe that is .0002" out (2 tenths), and then put a perfect #5 taper in it, you are still two tenths out. If your #5 taper center is 2 tenths out, you can clock the two errors opposite from each other and come out perfectly concentric, or you can clock them with the errors in the same direction, and then will have 4 tenths runout. And a lot of other possibilities as well, depending on how things are clocked. With a 3-5 taper sleeve, and a #3 taper center, many results are possible, both good and bad, from the combination, depending on their individual runout and how they are clocked. Again, nothing is perfect. Test your lathe and your tooling, and mark the high spot and runout value on each piece, then you can use the inherent imperfection of our world in your favor to make your end result dead nuts on. Of course, this takes a fair amount of time and fooling around. Or, you can do as many do, and just assume everything that is shiny is accurate, and blame the inaccuracies on their own work, which it is...

Not all work needs to be perfect, or within 2 tenths. Far from it. For most of what most of us do, none of this matters in the least. Only get fussy when the REQUIRED tolerance of the work is fussy. The rest of the time, git-er-done...
 
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darkzero

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#4
Somethi g to consider, I've posted this before....I had the same thought in the past so I went & bought a MT5 dead center to replace my MT3 dead center & sleeve. It didn't work out for me. With the MT5 center, it stuck out too far & none of my drive dogs would not reach my drive plate.

Those who use a face plate for a drive plate with an attached post & straight dogs won't have the issue. I did not feel like modifying all my bent arm dogs to reach my drive plate so I sold the Mt5 center & went back to using the sleeve.







 

Superburban

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#5
Most books say to recut the point every time you reinstall the center (No, I don't either), which would make either style just as accurate. The few times I have used my MT3, with the MT5 to 3 sleeve, it had no noticeable error.
 

darkzero

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#6
Most books say to recut the point every time you reinstall the center (No, I don't either), which would make either style just as accurate.
That's what I've been doing. I made a straight shank center & chuck it in my cheap 3 jaw chuck, remachine the taper everytime (or if needed) & use one of the jaws to drive the dog.

I don't even remember the last time I used my drive plate that's shown above.
 

Bob Korves

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#7
A tool post grinder can do a very nice job of truing up center points, and many other cleanups of precision tapers. I need to have a marathon, cover all the lathe parts carefully, and just do them all at once, and then do a spotless job of cleaning up the gritty mess. Also run a shop vac the whole time sucking up fine grit. They really look nice afterwards, and can be quite accurate if marked for indexing them later with your spindle. A spindex on a surface grinder also works for grinding points on straight shank tools.
 

benmychree

John York
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#8
I am a purist in this respect; turning between centers is the only way to ensure concentricity on work that has to be machined from both ends. If I plan to grind the diameters of such a shaft, turning between centers is of value, because it makes it possible to leave a minimum allowance to grind; if a shaft, roughed out by chucking, it is possible that the diameters may be considerably eccentric, and when ground, may shift around as they are ground in turn, necessitating a rough and subsequently a finish grind, wasting time.
If the headstock center and its sleeve are marked with match marks (and the spindle itself) repeat concentricity can be had when the centers are installed in their respective tapers, within close limits; for the ultimate accuracy, the center should be recut, Headstock centers, accordingly, should be left soft so that they can be recut as required. I have used the four jaw chuck as a driving plate occasionally, but very much prefer to use the driving plate.
I prefer to rough the work out by chucking, as the chuck affords ridigity and allows heavier cuts because the work is better supported, but at the expense of concentricity; then proceed to turning between centers for the finishing for accuracy.
 

Silverbullet

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#9
I don't think any lathe new comes with a full size head stock center. They always send the reducer and two dead centers. By the way the correct term for the center in the head stock is live center. Just saying
 

darkzero

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#10
I don't think any lathe new comes with a full size head stock center. They always send the reducer and two dead centers. By the way the correct term for the center in the head stock is live center. Just saying
True that from what I've seen. Seems like they usually come with a sleeve to match the same size for the tailstock. And possibly to reduce stick out like what I experienced posted above.

As far as live center goes, just habit for me I guess, perhaps a bad one. I was taught that a live center is a center used in the headstock & a dead center is in the tailstock. But lots of people these days call it incorrectly or differently & get confused so I just go with it. Many people will refer to a solid center a dead center no matter where it's used & refer to live centers as the revolving or ball bearing type. I wonder why. Maybe cause that's how they are sold these days or maybe the terminology changed when revolving centers were invented? I assume revolving centers must have not always been around?
 

Chipper5783

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#11
The center in the headstock does not need to be hard (per comments above) - once recut, it will be bang on as good as the lathe can produce (better than a 5MT or 3 MT + adapter). If that "guy" were to recut his soft center and match mark it to the spindle, it would be quite accurate (since even marked it does not go back exactly the same each time). I can't imagine that for 99% of practical machining work it wouldn't be good enough (I'd wager that there would be other sources of error which would be more significant).
 

mikey

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#12
I don't think any lathe new comes with a full size head stock center. They always send the reducer and two dead centers. By the way the correct term for the center in the head stock is live center. Just saying
You're probably right for most lathes. My Emco Super 11 came with a 5MT center for the spindle and a 2MT for the tailstock, no adapters. Leave it to the Austrians to be the exception.

I've always assumed a live center was a rotating center in the tailstock and solid centers were dead centers. I don't think it matters a whole lot as long as we know what we're referring to but its interesting.
 

Bob Korves

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#13
Yes, the nomenclature for centers has become hopelessly confused. I use the terms hard, soft, or ball bearing along with spindle or tail stock to describe lathe centers. At least people can visualize that and are then free to call them whatever they wish. I do not use the terms live and dead, not even in my own mind...
 

cathead

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#14
Yes, the nomenclature for centers has become hopelessly confused. I use the terms hard, soft, or ball bearing along with spindle or tail stock to describe lathe centers. At least people can visualize that and are then free to call them whatever they wish. I do not use the terms live and dead, not even in my own mind...

How about some biological nomenclature? Maybe Necroticus centricus ...................:)
 

benmychree

John York
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#15
I don't think any lathe new comes with a full size head stock center. They always send the reducer and two dead centers. By the way the correct term for the center in the head stock is live center. Just saying
You are correct in your statement that all lathes came with a sleeve; this allows BOTH centers to be trued up in the spindle, although a tool post grinder would be necessary for the tail center to be trued as it is always hard. The head center generally came with a recess turned near the big end to indicate that it is soft; both ends were the same size taper.
Incidentally, years ago, I had a good sized lathe that was probably from the 1850s that had square tapered centers, about the same taper as a #3 Morse --- go figure?
 

Superburban

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#16
From my High school days, I remember them as a soft center that is for the headstock, a hardened or carbide tip center for the tail stock, and a ball bearing was called a live center. I can still visualize the quiz that covered the various dead centers, and different live centers. We made the soft centers from stock.

The various books from around 1900, also have many differences in descriptions, so the confusion is nothing new. Here is the funniest I found, from a 1910 book, IIRC. A headstock center is normally live,and the tailstock dead. But a live center in the tailstock can withstand heavy pressure. Its like the paragraph was written by three different authors. :eek:

livedead.PNG

livedead2.PNG
 

mikey

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#18
Yes, the nomenclature for centers has become hopelessly confused. I use the terms hard, soft, or ball bearing along with spindle or tail stock to describe lathe centers. At least people can visualize that and are then free to call them whatever they wish. I do not use the terms live and dead, not even in my own mind...
Hmm, so a center in the headstock is actually called a live center because it revolves like its alive, but if you stick the same center in the tailstock then it dies and then becomes a dead center because it doesn't revolve. BUT it doesn't really revolve in the headstock either so it was never alive to begin with; it just spins with the spindle so its actually a dead center that is being deceptive about being alive. Tricky devils, these centers. I'm going to call all of them dead and call my spindle a live spindle; that will show them.

Good thing we don't consider a live center sentient or we'd have to talk to the damned thing! With my luck, my live center would be female and I'd have to listen to it (no offense, ladies, just some husband humor). :D
 

joshua43214

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#19
I will toss in my 2 pennies on the subject of live centers.
I use a stub of soft steel in the 3jaw as a live center. I cut it fresh each time I use it, even if I had a tool post grinder, I doubt I would grind it.
This works well for me since I use the 4jaw almost exclusively when I put work in a chuck. My chucks are well fitted to my spindle (D1-4 nose), so swapping them back and forth does not seem to cause any issues, though I will often recut the center just because it is "best practice."
I have had some parts go on and off the lathe upwards a dozen times as they either get pushed aside for another project, fitting up, or for milling operations, and they always go back on as concentric as I can measure with my DTI.
Like mentioned above, I like to do my roughing work with the material in the chuck, and try to limit my DOC between centers to under 0.070"

As for the other stuff. A sleeved #3 is just as accurate as a #5 center assuming it has been clocked. A #5 rolling center is an order of magnitude stronger than a #3 center, but is also substantially fatter and that much harder to get a tool around, and you can give up all that stiffness using an extended center. On the other hand repeatedly swapping the sleeve around tooling does cause wear and tear on the sleeve.

I also fall in the "old school" camp that defines a dead center as the thing that goes in the tail stock, a live center is the smooth pointy that in a headstock, and a drive center as a pointed thing with spurs that goes in the headstock (seen mostly on wood lathes). If it goes in the tail stock and rotates passively with the work, it is a rolling dead center. I don't get hung up about it though, and often refer the rolling dead center as a live center, so long as folks know what I am talking about there is no problem :)
 

Bob Korves

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#20
Hmm, so a center in the headstock is actually called a live center because it revolves like its alive, but if you stick the same center in the tailstock then it dies and then becomes a dead center because it doesn't revolve. BUT it doesn't really revolve in the headstock either so it was never alive to begin with; it just spins with the spindle so its actually a dead center that is being deceptive about being alive. Tricky devils, these centers. I'm going to call all of them dead and call my spindle a live spindle; that will show them.

Good thing we don't consider a live center sentient or we'd have to talk to the damned thing! With my luck, my live center would be female and I'd have to listen to it (no offense, ladies, just some husband humor). :D
It does not appear that you are responding to my post, Mikey. What I would say is that I have a soft center in the spindle, or a hardened center in the tailstock, or a ball bearing center in the tailstock, but would not use the terms live and dead at all because their usage has become hopelessly confused. What am I missing?
 

mikey

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#21
It does not appear that you are responding to my post, Mikey. ... because their usage has become hopelessly confused. What am I missing?
You're not missing anything; I was just trying to add some levity to the confusion, Bob. Sorry if quoting you confused the issue. :)

We all know what these little suckers are and how they're used. I think I'll side with you and not refer to them as live or dead. Maybe they'll die from the inattention and stay dead.