Spindle Morse Adapter...or no?

Splat

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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?
 
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
 
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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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.

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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.
 
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.
 
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.
 
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.
 
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
 
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?
 
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