Truing L1 spindle?

I recently bought a Hardinge collet chuck for my Clausing Colchester 15x48, and when I took off the 3-jaw to install the new chuck (I haven't had the lathe long, and haven't taken it off before) I discovered the spindle nose was pretty hammered - like the previous owner never cleaned it before installing the chuck. There are dents and high spots all over, which makes me reluctant to simply stone the high spots and call it good. At the same time, I'm not too excited about turning it - because then I'd have to figure out what to do with the nut. At least I've figured out where some of the runout was coming from - but what to do about it? Any suggestions?

Also - according to at least one source (I haven't looked much), the L series taper angle is 8 deg 17 min 50 sec - maybe my math is bad, but that looks like 1.7317 in/ft. - real close to the square root of 3. Why? Am I missing something?

thanks,
Andrew

Doesnt that sort of stupidity just piss you off? Looks like you need to dig out the tool post grinder. About all you can do with the nut is to remove it. Unfortunately to do this you need to remove the spindle as the nut goes on first.

Mines a L00 but was darn similar when i got it. In the end i simply went the stoneing route. First though using the chuck that was on there i gripped the other chucks and stoned the matching dents out of there ids. Then i simply removed the nut, just leaving its rear plate on the spindle then removed the key way and stoned the spindle with it spinning. Stopped the secound i got rid of the Peeks though! Reassembled and the results pritty darn good.

Part of the problem on my lathe is the chucks have like a small recess bettwen chuck - backplate + the slot of the key way. This fills up with any through boring work. Its a pig to get clean. I now have a old tooth brush for just that job. But its undoutably where the swarft that caused the dents hid! Only to get knocked out into the tapper on assembly to the spindle nose. So you may find you need to do a lot better than a casual wipe to prevent it from reocuring!

Oh you may well not have to remove the spindle to get the nut off. On the harrison there a little screw and the nuts a threaded tube. It simply unscrews from a plate that is permenantly trapped to the spindle!

adama said:

Oh you may well not have to remove the spindle to get the nut off. ...

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This arrangement is common for L spindle noses- my Willson has a similar arrangement, a two piece nut, where recessed cap screws hold the keeper plate onto the back of the nut proper. Without close inspection you can't see the joint.

I'd go for a toolpost grinder myself with a spindle as dinged as yours, (obviously using a DTI to get the compound to the right angle) but if you do decide to stone, I'd recommend using a narrow slip stone on the raised lip around each bruise first, because if you go straight to running it under power as it is, the bruises will possibly bounce the stone.

B5.9 states it is 3 1/2" per foot on diameter taper. Big end of spindle taper on L1 is to be 4.125/4.127". Taper just says To Fit Gage.

John Oder

8 deg 17 m 50s is 8.2972 deg

Tan of 8.2972 deg is 0.1458

times 12 is 1.75 inches per foot on radius,

So... both figures agree.

(and, yes, the OP's " math was bad")

Athough it looks pretty bad in the picture, I would wager that its locational accuracy will be much better by carefully stoning off the high spots surrounding the dents rather than trying to accurately regrind it with a tool post grinder.

I'd paint it with some of the bluing stuff they use for scraping (a magic marker will work also), and use your highest quality chuck or face plate to show you the high spots, stone them and repeat until there aren't any high spots.

Paul T.

I would back up one step further and mount your chuck on the spindle.

Chuck up some precision rod/tube and do an actual check of runout etc.

If a 4 jaw chuck mounted can be dialed to run straight with no runout then it really doesn't make much difference what the spindle taper looks like, heck it could have 1/4 holes in it

If you find it impossible to get any chuck mounted that will run true then, start messing with the spindle.

My 2c

MwTech Inc said:

If a 4 jaw chuck mounted can be dialed to run straight with no runout then it really doesn't make much difference what the spindle taper looks like, heck it could have 1/4 holes in it

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Of course it doesn't matter if there are holes in the spindle - they're not touching anything. It's the high spots around the dings that are going to screw things up!

Just to see what how much it would help, and to see if I could get away with not removing, installing, grinding, removing, and installing the spindle (the nut is not otherwise removable) I stoned it this evening. The low spots are still there (it looked like a blue-spotted dalmatian after I was done), but the collet chuck runs true within .001". I'll go over it again to see if I can get it a bit closer, but I'm pretty happy with the results. Now to clean up the tapers in the 3 and 4 jaws...

Thanks for all the suggestions.

Andrew

You are running the risk of making it worse if you try to grind it off. I'd just stone the high spots around the dings off. If you grind it,and the taper is off AT ALL,your chucks will never run true. And,if you try MORE grinding,and get the nose a wee bit too small,you'll really be in trouble.

I have ground the D6 spindles on some of my lathes,but I don't know your skill level. This is not something to underestimate the consequences of,especially with that loose ring in the way. That would be harder to grind than a D type spindle.