Spindle Binding When Trying To Bring Tolerance Into Spec.

jbmauser

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I posted this in the wrong forum so if the administrator wishes he can pull it or from the beginner forum or here. I do think there is a remedy just need to grouse a bit I guess.

I watched a video online and saw how to check for play in the spindle of my SB 9C lathe. I put a bar in the chuck end and got over 4 thou of movement. I put a wrench on the the single bolt on the chuck side to remove it and pull the shims as instructed. The bolt was not very tight so I first torqued it down snugly and checked it again and the play closed to 2 thou but the spindle had a little resistance when turned by hand. I backed it off a tad and it spins by hand. But not free wheeling. I moved to the tail which runs a lot of oil and I found that bolt as not snugged down hard. I took a reading of over 4 thou and snugged it down and it binds on a high spot like the shaft is egg shaped backed it off and it spins free. I have ordered a needle bearing and two hard washers as recommended to replace the fiber bearing. This should cut down on the oil leaking.

I know it is more than likely the headstock opening that is egg shaped and not the spindle but the fact remains it only binds on a small area as the spindle is turned by hand. So I backed off both front and back bolts till the spindle spins freely with a bit of overtravel when spun by home. When the needle bearing comes in it may hopefully remedy the oil leakage. I do not work in high tolerances (yet) so it is what it is. I guess the adjustment arrangement where you can only adjust one side of the bearing "CAP" of necessity would create an oval rather than a circle but I would think if it would bind it would bind over the entire radial range not just a 10 to 15 degree point. discouraged and a bit confused. JB
 
If it is only binding on one portion of a revolution of the spindle, then the spindle is bent or out of round, probably a bent spindle unless someone was messing with the spindle bearing surfaces. I do not know the best way to proceed with your issues, probably some one else will speak up here...
 
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Bent spindle, wow! I guess I will have to look at the original spindle that I still have. It was galled when I got the lathe. I had taken the spindle out of a beat up 36 in. SB that I cannibalized and parted out but kept the spindle as it looked better than the original, It is scored and now it seems it may be bent. I guess I will have to build a jig with ball bearing contact points to spin the spindle and check for true. Perhaps I can run it on my wood lathe to check for a bend.
 
If you have a concentric spindle without runout and concentric bearings, and a very small clearance, it will spin freely. As the bearings are made tighter it will eventually contact the bearings, pretty much all at once. If the bearings have a high spot or spots and the spindle runs true, then it will spin freely until tightening it down makes it hit the highest bearing high spot, which will start to rub, continuously if the spindle has no runout. If the spindle is bent, as you tighten the bearings, it will start to rub intermittently on the first high spot it meets, and only rub on the high area of the bearings. That appears to be what is happening with yours.

You might want to post some pics of the wear on the original spindle and the bearings. Sometimes, things that look really bad are not actually a big issue.
 
Before I tore it down, I'd run it to a spot that seemed to bind and check for play with an indicator on the spindle, both front and back. That way you might be able to narrow down the end that actually has the tight spot. One bearing may still have clearance when the other does not. If they both show no movement, likely you do have a bent spindle. If you have vee blocks and a good surface, it may be better than your wood lathe, but that's not a bad idea.
 
Tony it is definitely the rear bearing that the shaft is binding in. I just got back in and shot the original spindle two shots of each endDSC_0424.JPG DSC_0425.JPG DSC_0426.JPG DSC_0427.JPG
 
Wow! that's not good! I don't know if you can fix scaring that bad. I have taken a oil stone and mineral spirits, with the spindle spinning in another lathe, smooth out some of the galling. The only way you are going to remove it all is to have the spindle reground and superfinished. Then you have to deal with the headstock casting, which would have to be bored out and bronze bushings made to fit. Unless, you have one of the older South Bends that have bronze bushings in the spindle.
Mentioned something about a bent spindle? Get you a set of vee blocks, space them out on the bearing surfaces and check the middle for runout, if ok, move the vee blocks to one end of the spindle, and check. Keep moving the vee blocks around in different positions looking for runout. If any runout in any one place, could be bent. Lets hope not. BTY- you don't need a surface plate to set vee blocks on. You can do it on your mill table if you have a mill and even use the kitchen counter top, too!
 
Update. I removed the spindle and set it up on my wood lathe and took measurements. The old spindle which was not in the SB read out 4 thou on each end. I figure this is the error of the wood lathe. The offending spindle which is not all scratched up read 8 thou at the tail which is where I was haveing the problem and 4 thou at the head.

I put the original spindle which is pictured above back in the headstock and after adjusting the tightness of the bolts got 3 thou play on each end and no binding when the spindle turns. It seems there is a bit of a bend in the better spindle.
 
Question on spindle condition. If the spindle has wear or damage as above and there are no rough spots that are "high" (I ran the spindle over with a file which skates on the hard surface but removed cast iron that had welded itself to the surface) the spindle should still float on a coat of oil and the grooves that are etched into the spindle should just fill with oil and retain it as there is no radial action to move it to the outside.... Does that sound reasonable. I have run the smoother spindle for some time with loose tolerances and proper lube. I doubt the casting has any high spots to further degrade or etch into the old spindle as I am fastidious about oiling.
 
It should be fine. Do the headstock castings above the journals heat up much? The only other thing I might do is polish that original spindle - start with 400 and move up to 1500 or 2000 grit.
 
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