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Sheldon Xl-56 Spindle Dead Center

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Danb

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#1
I have a Sheldon XL-56 and would like to get a center for the headstock. It has a 1-3/8" bore and based on my measurements I thought it would be a 5MT. I've read here and elsewhere that there may have been a bushing (that I don't have) that would accept a MT or that the spindle taper is LOO? My searches do not find LOO tapers so I'm at a loss--as usual. Any help educating me would be appreciated.
 

wa5cab

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#2
Dan,

The "L" tapers (L00 through L3) are keyed male tapers with captive draw nuts for mounting chucks onto the spindle nose. The female taper in the spindle bore can be anything larger than the spindle bore and smaller than the male taper. I have no idea what the standard XL-56 female taper was but If your measurements and calculations say 5MT, that's probably what it is.

The Lathes.UK site has a pretty good write-up on spindle nose sizes including the "L" series. "L" stands for "Long Taper". and the series may be described as "American Standard Long Taper With Key and Draw Nut". But there is nothing in any of the spindle nose definitions about the female tapers. I think that on this side of the pond, the female taper would typically be either the largest Morse Taper that would fit. Or a collet taper. Usually either 5C or the manufacturer's proprietary collet.
 

eeler1

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#3
Picture would help. 1&3/8" is awfully small for a 5MT
 

Danb

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#4
My vernacular is probably the problem. The spindle nose is a 2-1/4" 8tpi. The inside diameter at the nose is 1.625. By taking a boring bar on the x-slide and measuring the difference in the interior I get a diameter of 1.475. The taper is 2-3/4" long. Doing the math I get a taper/ft of .654. The SB book lists the taper for 5MT at .6315 but my ID interior is pretty rough since it's hard to see. It's probably coincidence that the inner ID is the same as the SB table for 5MT. The 1-3/8" is the smallest ID of the spindle. I've made some 2MT on my little 7x16 with a home made taper attachment but it took several iterations. I was trying to forego that experience on the Sheldon, besides, I don't have even a home made TA for it. Thanks for the help. I should probably buy a 5 and see if it fits.
 

Ed ke6bnl

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#5
I know nothing about your machine but am told that my LOO on my 11 in. Rockwell is MT 4.5 and it has a bore of 1 3/8 in. not sure if that can help you.
 

mzayd3

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#6
I have a UXL-56. I also have a mt 5 dead center for it. The mt-5 seems a bit big even though it was confirmed by the Sheldon yahoo group. The mt-5 sticks out a little far. I am still investigating it. I think a 4.5 might be more apro pro. Don't know for sure though.


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4GSR

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#7
It is a Sheldon special. It's based on a no. 5 Morse taper but smaller at the big end, at 1.625 dia.

Sent from my SAMSUNG-SM-G920A using Tapatalk
 

wa5cab

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#8
To add to what Ken said, Machinery's Handbook gives the ID of the large end of a female 5MT as being 1.748" and the taper per inch as 0.05262". If you have two appropriate type dial indicators, you can measure the actual taper per inch independent of the exact diameter. Set a regular style indicator on the bed to indicate carriage travel. Mount a centering type in the tool post. Advance the carriage to run the ball on the end of the centering type just inside the hole. Touch up and zero both indicators. Advance the carriage 1.000". For 5MT, the centering indicator should read half of 0.05262" or 0.02631". According to what Ken wrote, Sheldon must have shortened the large end of the taper slightly. But if the taper is 0.052+, a 5MT dead center should work fine.
 

Danb

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#9
Set up the Indicators as described with the TI meas inside at 1200. Got a half taper of .0273/in instead of .02631. Thought there might be some dings so I took readings every 1/4" and got an average of .0277. Thought maybe the ways were worn enough to cause it ( although the swirly marks are still visible) so moved the TI to 0900 (looking at the head stock) and got exactly .0300 whether by inch or by quarter inch and the increments were exactly the same. Thought the bearings might have something to do with that so I twirled the spindle and if the TI moved at all, these 64 year old eyes couldn't see it. Since the Sheldon guy says it has a 5MT I'll just get one and if it's too long for the dogs to reach the face plate I'll cut another 60. If it don't fit I'll make a center to go in the 4 way and hope I don't need the extra 3". At any rate, this has been interesting and fun. Thanks to all for the help and suggestions. Now I just need figure out what to make until the snow n rain clears out for a while.
 

wa5cab

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#10
Well, that's moderately confusing. If you have the time to fool with it, I would repeat the test, but at 0300, 0600, 0900 and 1200. I'd rather have all four readings before I stick my neck out and say what I think the readings could mean.

I tend to agree that it's unlikely that the bed height could change enough over 1" to account for anything much. But one way to maybe eliminate a change in bed height as the explanation of not getting close to 0.06231would be to stick the compound slide out 1", rerun the 1200 test, and with the carriage remaining forward one inch, retract the compound exactly one inch and see whether or not the centering indicator returns to zero.
 
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Danb

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#11
Robert,
As a Task Master you remind me somewhat of long ago dif eq and q-physics profs I was fortunate enough to have--they humored me and convinced me to work a little harder. I did a shorter version of what you suggested with the DI on the face of the spindle nose and the TI @0900. Before plunging into the taper I rotated the spindle while in contact with the DI just to see if there were any bobbles. None. The first time I ran into the taper I got a .0258 instead of .02631--quite different from what I got the other day ( .0300) but still disapointing. Did it a couple more times and got different answers. Did it once more and then turned the spindle ever so slightly and got .0262. Repeated @ .0263, .0264 and so on so I thought I was getting reasonable results. Moved the TI to 1200 repeated as above and got very similar results. Apparently my made in China TI is acting very much like it was made in China, but it's the only one I have so far. Anyway with a little nudge on the TI it convinced me that the taper is indeed an MT5--just as other responders said above. Enough exercises like this and I may learn how to measure like a machinist.

As a side note, after after riding fences for the morning in rain showers and on a cranky mule, I needed a crank fix so when I got home I peeled a test bar (without tail stock) and interpolating the mic I got a difference of +/-.0001" for a length of 9". I was just starting 1st grade when this lathe was made and that made my day. Thanks to all.
 

CraigB1960

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#13
The Sheldon has what is called a Short MT5. The measurements are:
Short MT5 : Large end is 1.625 inches +/- .005” length of taper is 2-5/16” instead of 5-1/4"

I took a standard MT5 dead center, annealed it, then turned it down until I made a nice center.

One thing you could consider is if you have a 5C collet drawbar/adapter for your lathe, you can make a center with a standard diameter drill rod held in a 5C collet. There are dead center 5C collets on eBay that could also be used.

Like this: http://www.ebay.com/itm/HARDINGE-5C...829114?hash=item3600461dba:g:a7MAAOSw9ZdXKPy9 or this: http://www.ebay.com/itm/Hardinge-5C...841957?hash=item28165c5625:g:3FcAAOSwiYFXFuqV

(No affiliation with those eBay sales, just showing them for reference)
 

wa5cab

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#14
Dan,

OK. I'm glad that I didn't say before that the 0.300 reading at 0900 could indicate that the headstock is cocked toward the operator. FWIW, that was why I suggested repeating the test at 0300. But the test bar results probably indicate that that isn't the case!

One has to wonder about why several manufacturers created things like Short MT5 and MT 4.5. They have certainly caused problems for people later on.
 

4GSR

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#15
You can guarantee the machine tool builder got the taper right to a tee at the factory!
The Chinese test indicator more than likely has some error in it. Even some USA made indicators have error in them. They just don't tell you about it up front. Plus test indicators were never design for real measurements in general but we are all guilty of using them as so.
 

eeler1

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#16
Ah, the short MT5 taper!! I had an emco super 11 that also had that taper, I believe, but had forgot about it.
 

CraigB1960

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#17
One has to wonder about why several manufacturers created things like Short MT5 and MT 4.5. They have certainly caused problems for people later on.
The short MT5 was supplied so that the machine spindle would have the 1-3/8" bore and the 2 1/4-8 threaded spindle while supporting 5C collets. A true MT5 would require a larger spindle and yet would not provide any more benefits such as transmission torque for using the complete MT5 taper length.

The cost of the redesigned machine would be much higher for no real additional benefit.
 

wa5cab

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#18
Well, you're probably right but there would be one benefit - far less confusion half a century on. :)
 
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