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.
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Sheldon Xl-56 Spindle Dead Center
- Thread starter Danb
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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.
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.
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.
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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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It is a Sheldon special. It's based on a no. 5 Morse taper but smaller at the big end, at 1.625 dia.
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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.
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.
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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.
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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