Completely dickered 12X36 spindle, options?

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Mwmx54

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Hey guys!
I picked myself up a an old craftsman badged 12x36 (with the timken bearings) a few months back and have been having a great time learning to use it. I have so far made a little gear indexer and cut my own gears, with the milling attatchment that came with an old 9" atlas (metal craft badge I think) it was trashed but came with lots of tooling and other neat stuff, I like having parts machines for my parts machines;) so my latest project has been getting my lathe level and aligned and I have come across a problem, I noticed no matter what I did I couldn't get the spindle to run true, so I decided to try bluing my collet chuck and noticed hey, only about 1/2-3/4 of an inch is in contact, so I measured the through hole of the spindle, and guess what? Someone bored it out! So I decide I have a little room to try to enlarge the taper and still have a usable but slightly larger mt3, so I spent way too long setting up my compound to cut the taper, I took a few thou out of the taper and now get about 1-1/4"-1-1/2" of contact on my dead center, but my collet chuck is now too small to fit. So I looked through epay and there are quite a few used spindles, for 70$ plus! Or I can get a whole headstock for about double, and have some more spare parts. My other option is to make a new spindle, so I checked the online metal suppliers and I can get a 12" bar of DOM that is 2"OD and .75"ID is this a suitable material, I also have a few feet of 3" C.R. Bar, but that would take a lot of machining... but maybe it's a better material? Not sure what used originally? Plus I have it on hand. Sorry for all the words, think of this as my introduction and a question. Also, if anyone has a spindle laying around let me know. We could work a trade, I have all sorts of stuff for these lathes including a complete 9" with a few good parts still. Not the spindle though, it was trashed when the Babbitts that it ran on failed.
Thanks!
Here's some pics:) don't mind the messy garage:)
I added the 3/4" leadscrew and put a newer carriage with auto cross feed, as well as an AXA qctp
IMG_5436.JPG
And here is a couple of my gears I made.
IMG_5825.JPG
 
Morse taper 3, taper is .050195" per inch (on the diameter). Therefore, if you increased the MT3 by .005" diameter, you sank the gage line (.93800" diameter) by .10".
Can you cut/grind a little off the back of the Collet Chuck head to let it seat in the taper you have?
Buy a 15/16 (.9375") bearing ball and measure how deep your gage line is from the front of the spindle.
That will tell you how far you'd have to "relieve" the collet chuck head.

If the MT runs true now and has an acceptable form, I'd avoid making a new SOFT spindle. YMMV but I would consider that a waste of time.
If you can't help yourself (have to make a new one) I suggest that it's not as simple as it may seem to make a quality spindle.
Don't forget that CRS is loaded with stresses that will want to relieve as you cut it and may distort over time. I don't have any experience with DOM tube in those dimensions.
If you used a material that could be hardened, heat treated and finish ground, you certainly would have improved the lathe and exercised your skills and wallet.

If you must replace the spindle, IMO, buy a replacement part.

I don't know exactly how easy it is to bend a spindle in your lathe, but IME, lathe spindles are not easily bent.
Runout problems (not bearing related) are usually the result of dings and damage caused by mating dirty parts.
If the MT3 is a problem, I'd try a light "cleaning" by hand with an MT3 finish reamer long before deciding to recut it.
 
I've heard (but never seen it done) that if there's a few thousandths missing, you can get a hard
chrome plate, and build it back up... but only a few thousandths. Then, you'd need to get it
ground to accurate MT3. Not sure, though, that the surface would engage like a good taper
should, 'cuz now it's the wrong material. It might be worth asking about.
For a quick fix, a shimstock MT3.03/MT3 adapter would be as easy as making
a funnel from sheetmetal.
 
The main concern is that whenever they bored the ID of the spindle, that it warped, I considered removing some material off the back face of the collet chuck, but it seemed like it would need to be a lot. It's a pretty loose fit now, it feels like atleast 1/16-1/8" of an inch of wobble but the chuck always fit almost the way in. Ive taken the spindle out of this machine before when I first got it to clean everything, it was pretty bad, bearings were all good though. I'll keep looking for a replacement spindle, I imagine it would be one of the expensive parts to get straight from clausing right? They wanted over $700 for a leadscrew. But half nuts are pretty cheap.
 
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As far as reaming goes, that would have been ideal, I had no mt3 reamer though, and it was already screwed up, couldn't make it worse, my cut mt3 blues very nicely though. And my dead centers still stick out atleast 1.5" to the tip. Still pretty worthless not being able to use a collet chuck though. I should have known that such a light taper wouldn't take very much to move the whole thing as far as it did.
 
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What do you guys think about boring my spindle taper more, and taking an mt3-mt2 sleeve to where it fits all the way in touch wif th the tip of the spindle, then gluing and pounding it in permanently? And boring it back out to mt3. Or even taking an mt3-mt4 and turning it down a little, just so I can get full or atleast more than 1.5" contact along the taper.. and does anyone know exactly what material the spindles are made from?
 
Mwmx54 said:
What do you guys think about boring my spindle taper more, and taking an mt3-mt2 sleeve to where it fits all the way in touch wif th the tip of the spindle, then gluing and pounding it in permanently? And boring it back out to mt3. Or even taking an mt3-mt4 and turning it down a little, just so I can get full or atleast more than 1.5" contact along the taper.. and does anyone know exactly what material the spindles are made from?
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Won't a MT2 sleeve reduce your "through the spindle" size substantially? And, wouldn't you have to buy an MT2 collet chuck (to achieve what you said you wanted)?
If your collet chuck's shank is replaceable, just make a longer MT3 to fit your spindle, as is.
I think it would be a bad idea to remove more metal from the ID of the spindle. I wrote earlier "lathe spindles are not easily bent". If you keep cutting, you may prove me wrong.

I have no idea of your financial circumstances, but a replacement spindle from eBay is looking more attractive all the time. Invest in a finish reamer for your taper(s) also.
In the future, take extreme care to verify that your tapers are clean and free of burrs before mating.
 
You're right, but what I meant though was just removing a little more from the spindle taper, so that an mt3 to mt2 adapter fit all the way in flush with the tip of the spindle. Then boring the sleeve adapter back out to an mt3. Leaving probably too thin of a sleeve left though, I could also make a long mt3 taper as thick as I want, then boring as much as I felt necessary from the spindle to get the right thickness of what would be a sleeve(bushing) semi permanently glued or even tig welded in place, I would be no worse off than I am now, as I'm fairly certain my spindle has a bend from being bored out to about .880" if I recall correctly. I have a sleeve that when put into the taper, still extends past the the nose about .75". So couple more thou out of my spindle and it should fit all the way in. But you are right. $70 on a used hopefully true and not dickered spindle off eBay is the ideal route. Just can't ever be sure of what your getting from the bay.
 
Mwmx54 said:
You're right, but what I meant though was just removing a little more from the spindle taper, so that an mt3 to mt2 adapter fit all the way in flush with the tip of the spindle. Then boring the sleeve adapter back out to an mt3. Leaving probably too thin of a sleeve left though, I could also make a long mt3 taper as thick as I want, then boring as much as I felt necessary from the spindle to get the right thickness of what would be a sleeve(bushing) semi permanently glued or even tig welded in place, I would be no worse off than I am now, as I'm fairly certain my spindle has a bend from being bored out to about .880" if I recall correctly. I have a sleeve that when put into the taper, still extends past the the nose about .75". So couple more thou out of my spindle and it should fit all the way in. But you are right. $70 on a used hopefully true and not dickered spindle off eBay is the ideal route. Just can't ever be sure of what your getting from the bay.
Click to expand...

The eBay definition of "USED" includes the requirement that the item be fully functional.
Read the sellers description, If description is lacking, communicate with the seller to ask questions and tell them what you want (A fully functional spindle w/ good bearing journals and MT3 taper?).
If item arrives "not as described" you get all your money back including return shipping.

Good luck. My work is done here.
 
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