Atlas-craftsman 101.07301 Chuck Wobble

OK. If they faced the flange, they probably held the spindle with a 4-jaw clamping on the front bearing journal area. If the spindle is bent, it is probably bent between the two journal areas. Chucking on the front journal and facing the flange won't have helped any. Check the flange runout with the spindle mounted in the headstock. If it is about the same as before, face it and see whether or not that helps (it should). If it is better than before, mount the chuck and with a .002" or .003" feeler gauge, probe the interface between the flange and the chuck, looking for a gap. If there is a gap, the chuck is stopping before it gets to the flange.
 
Thanks Wa5cab
I don't have the lathe up and running yet. I still need to get a motor, get it mounted to the bench and get some tooling. Will have to wait for a while for the cash flow to catch up. Thanks ED
 
I got over my:confused: :dunno: and went out to the shop and measured the face of the flange and it is out about 1/3 of 1 thousands. I have a feeler gauge somewhere but at the present time it is MIA. The chuck looks tight but when I hold a little LED flashlight behind it I can see light in the crack between the chuck and the flange.
 
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I went back out to the shop and tried the old paper feeler gauge and it is not going up against the flange. I keep looking at the threads in the chuck and am thinking about just getting a new chuck. ( I think it was 10 tpi and someone tapped to 8 tpi ) Is that a good idea or am I running ahead of my self again?
 
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Ed of all trades said:
I went back out to the shop and tried the old paper feeler gauge and it is not going up against the flange. I keep looking at the threads in the chuck and am thinking about just getting a new chuck. ( I think it was 10 tpi and someone taped to 8 tpi ) Is that a good idea or am I running ahead of my self again?
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It could be the chuck, but I would eliminate all of the other possibilities first. Normally I would have started with checking the spindle every way I could think of before doing any machining on it, or anything else. It is best to identify the root cause of a problem before trying to find a solution. Any troubleshooting is an excersize in logical problem solving, methodically following a path so see where it leads.

If a problem was found with the spindle, then correct that before proceeding to the chuck. This would give you a known good baseline for the rest of the process. The ''perfect'' spindle would have no runout on any working surface relative to the spindle bearing journals. The perfect spindle does not exist, so we try to get it as close as we can measure. This checkout should include the spindle bore.

If no problem was found with the spindle then the next step in the progression would be to the chuck. Given that the chuck won't register properly, the question is why. Does the spindle nose bottom out in the threads before the chuck registers on the flange? Maybe the bore in the chuck needs some relief in the bottom? Is chuck register only touching on one side of the flange? Any other possibilities? The chuck does not register on the threads (at least it shouldn't), but if the threads are cockeyed then that could cause a problem.

You are just going to have to work through it step by step to find the actual problem.

I hope this helps.
 
Jim, Thanks for your post.
I hope that is what I have done, with a lot of help from all of the replies I have received here. This is very new to me so I am kinda feeling my way like a blind man who lost his stick. Actually the blind man would do better. I am to the point with the spindle where the three measurements I know to make are down to 1/2 a thousands or less. The register between the flange and the threads is out just a little less than 1/2 a thousands inside the taper is around 1/3 of a thousands and now that I had the flange turned true it is a little less than 1/3 of a thousands out. I don't know what else to measure or how to measure more accurately I think I am right to say that one line on a dial indicator is 1 thousands of an inch. I do know that the threads on the chuck are a mess and I wonder if I could get them right how long they would stay that way. That is why I feel like getting a new chuck would be a good idea, I am asking because I know that there is much I don't know and I might have missed something else. Other than what I have understood from you all.
 
Ed,

If as you suspect, the chuck was originally threaded 1"-10 and was re-threaded 1"-8, the threads should look pretty much a mess. However, it should still work OK if the unthreaded bore and the face are OK. You haven't said and probably you don't know how much the cousin and a half took off of the spindle flange. But if there is a visible gap between the face of the flange and the rear face of the chuck, that is the next problem. That usually would indicate that when you screw the chuck onto the spindle, it is stopping on the threads, not against the flange as it should. You can cut the threads a little deeper or you can grind a little away from the first thread in the chuck. If you had a 1"-8 die nut, I would use that, but it's highly unlikely that you do. Assuming that your hands are still pretty steady (mine aren't), use a Dremel tool with a 3/4" dia. flat faced stone to grind away about 0.010" of the first thread. Chock the chuck on the bench with the start of the first thread at 6:00 o'clock (12 hour system) so that it can't move. It may be wise to tape the chocks to the bench. Position the Dremel parallel to the chuck axis (thread axis) and tilt it up at 30 deg. Grind 0.010" off of the thread face (this will be flat, not curved as the thread will be). Remove by grinding the sharp edge of the end of the thread. Make sure that there are no burrs on the edge of the thread by running your finger over it very lightly (don't want to cut your finger). If there are, remove them with a small piece of sand paper (220 grit or finer). Fit the chuck to the spindle. The gap should be gone or at least less. If it's gone, fine, if it's less but not gone, take another 0/005" off of the first thread in the chuck and see if that fixes it. But if the gap is still as bad as it was originally, then the spindle nose thread must be bottoming in the chuck. Report back for options.
 
Thanks Wa5cab
I wonder if that would work because it appears to me that the gap is only on one side of the chuck, I now, I should have said that in my post. sorry. The chuck is pretty tight on the flat register behind the threads but it is spinning fast enough to lock in place on the flange. imho. Could it be that whoever changed the thread did it a little off of "plumb"?
 
Ed,

The threads could be a little off of plumb. However, they will have some clearance. Is the gap always at the top. Do you have a 4-jaw chuck? And I've forgotten, for certain, but is the 3-jaw a 6" or smaller?
 
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