Bent Spindle?

Is it the same on the inside taper?

I suspect that what happened is that someone managed to spin a bearing at the nose end of the spindle, and did a knurling job to expand what was left to grip the replacement bearing -- and did the job somewhat unevenly. I've found light knurling on my L-00 spindle when I swapped it in to replace a 2-1/4x8 spindle (mine was a model 5418, and I wanted the better spindle nose. But mine came out pretty good, in spite of the knurling.

Good Luck, DoN.

The runout is the same on the inside taper, over .002. So much for buying old American iron. Paul

Well, you can pull it apart and check for any obvious signs of improper repairs, damaged parts, etc. Check the bearings to make sure they are not damaged (it may not take a badly dented roller or inner race to produce the symptoms you describe. When you get the spindle out, you can try rolling it on a surface plate to look for actual bending. If the bending is obvious, you can check around to see who can make a new spindle for you. A very servicable spindle is not that hard to make, especially if you can get access to a toolpost grinder. Make a spindle "blank", in other words, don't finish the inside taper or the chuck mounting threads until the spindle is back in YOUR lathe headstock. You can cut the inside taper with the compound slide. You use a known-good male taper as a master, and use blue dye to check the fit. When you get even marking of the blue dye, the angle of the compound is exactly right, then grind a little at a time until the arbor goes to the correct depth.

Cutting the taper for the chuck is easier, and you just test fit the chuck until it threads on smoothly.

If the bend in the spindle is only at the outer tip, you can just reface the backplates of all your chucks, and regrind the inside taper until it runs true.

Jon

Hi Paul;

The first question I would have is this does the issue, that is the excessive radial runout, occur if you take your measurements from different positions around the spindle? Also do you get a corresponding axial runout when the defective area passes by? My first thought is that a bent spindle is unlikely, it could very well be bad bearings. I've seen amny of a lathe that has failed due to poor lubrication of the spindle bearings. While I'm not familiar with the clausing, I have seen plugged oil lines and lack of maintenance attention cause these sorts of things.

The bearings may be tight but that does not imply that they are any good. Also on large spindles your really need to use a dial indicator to check the tightness of the spindle bearings. As far as a bearing problem if you should have a bit of galling on one of the bearing races that will cause the problem.

I suppose that the spindle could have been bent, though to be honest I've seen little of this. To check the spindle you would have to remove it from the machine and check it out with some inspection equipment. This is likely to be a lot of work but if your looking at the bearings it will be silly not to have it checked out. If the front bearing has turned like many have suggested, then you may need to look into the purchase of a new spindle. Refurbishment of the old spindle is always possible, but do not consider any rebuilder who does not have a history of rebuilding machine spindles.

Since the spindle is a key component of a lathe you will want this right. Frankly this issue severly limits what you can use the lathe for. Lots of luck.

Thanks Dave

I would think that if the spindle itself were bend, the bearings would bind badly at some point in the rotation. The fact that it does not, implies it is either a wear issue on the nose of the spindle, or a bearing issue.

Jim

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Paul:

I have a 14" Rockwell. It has a L00 spindle like yours. One thing I noticed about the lathe when I first got it was that changing old worn chucks required alot of fiddling to get the runout where it needs to be. My Rockwell chuck have Buck mounting plates with L00. The lathe came from a school, and the kids evidently did not believe in cleaning the spindle L00 nose before changing chucks. If you have a .0005 or .0001 test indicator, check the inside nose surface, mark the high and low points. Then do the same on the outside nose surface. If the highs and lows concide, then it may well be bent. If not, then probably the nose surface is worn. You can then do 2 things: Wiggle the chuck when you mount it to see if you can compensate for the worn nose area OR remove the spindle, metalspray the nose and have it reground. Much cheaper than making a whole new spindle.

Maxaggie