- Thread starter james.c
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sorry i might not know the correct names of the parts but you will probably know what i mean 
The 'shaft' that the chuck screws onto is running true or very near abouts. Its just that when you put say for example a solid piece of brass bar about 1'' diameter and start it up you can see the bar going up and down. Also when you start to take some metal off it, it will actually only do half of the bar untill you get deep enough into it to compensate for the movement if you see what i mean?
I shall take some pictures tommorrow and put them up it will explain it better also somebody may know what make the lathe is.
The 'shaft' that the chuck screws onto is running true or very near abouts. Its just that when you put say for example a solid piece of brass bar about 1'' diameter and start it up you can see the bar going up and down. Also when you start to take some metal off it, it will actually only do half of the bar untill you get deep enough into it to compensate for the movement if you see what i mean?
I shall take some pictures tommorrow and put them up it will explain it better also somebody may know what make the lathe is.
jugs
Dont wish to offend & annoy, but...
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All 3 jaw should be concentric & touch
)
Jaws seem to be positioned ok but may have a little taper wear.
This is where it may be difficult to explain.
Next thing to check would be the register if the chuck is bolted on to the back plate, usually three bolts. Back plate may be screwed on like Myfords. It could be the chuck is 120 degrees out and should have a mark 0 on the chuck and back plate to match up.
This is where it may be difficult to explain.
Next thing to check would be the register if the chuck is bolted on to the back plate, usually three bolts. Back plate may be screwed on like Myfords. It could be the chuck is 120 degrees out and should have a mark 0 on the chuck and back plate to match up.
Right bit of an update.. but not a very good one 
Had someone come and look at the lathe who knows quite alot about them and he has said that its actually the lathe at fault rather than the chuck. And i thought it was alright but he brought a dti along and it prooved otherwise
ahh well live and learn
Had someone come and look at the lathe who knows quite alot about them and he has said that its actually the lathe at fault rather than the chuck. And i thought it was alright but he brought a dti along and it prooved otherwise
ahh well live and learn
Er........... I hate to say this, but I very seriously doubt it. The only way for that to be caused by the lathe itself is if the headstock spindle is bent, which *really* *really* *really* takes some doing. Especially on a older robust lathe like in your pictures.
You can sling a lathe by the spindle and it wont bother it (might brinnel the bearings, so don't try it to see!). The one that I seen that was the exception, had split, we suspect because someone had inserted a division plate into the end of the spindle with a rawl bolt to hold it in, and turned the lathe on or it had engaged whilst running.
If it cuts taper, yes it can be down to bed->headstock misalignment, but to cut only one side of a workpiece is down to the spindle and its rotation alone.
Having said that, maybe its one of the 0.001% of used lathes that has got a bent headstock spindle however unlikely, if it IS, its possible to turn the register in suit on the lathe in question and correct the run-out there.
How did your friend test it? did he run the dti on the plate the chuck bolts to? or directly onto the bit of the nose that the chuck plate bolts to?
You can sling a lathe by the spindle and it wont bother it (might brinnel the bearings, so don't try it to see!). The one that I seen that was the exception, had split, we suspect because someone had inserted a division plate into the end of the spindle with a rawl bolt to hold it in, and turned the lathe on or it had engaged whilst running.
If it cuts taper, yes it can be down to bed->headstock misalignment, but to cut only one side of a workpiece is down to the spindle and its rotation alone.
Having said that, maybe its one of the 0.001% of used lathes that has got a bent headstock spindle however unlikely, if it IS, its possible to turn the register in suit on the lathe in question and correct the run-out there.
How did your friend test it? did he run the dti on the plate the chuck bolts to? or directly onto the bit of the nose that the chuck plate bolts to?
We took the chuck right off and just turned the lathe on without a chuck and he DTI'd the spindle that the chuck screws onto. The needle was moving up and down. Ive had a better look at it and i think it could be the bearings in this pic below? you can feel a tiny bit of play in them when the spindle is 'wiggled'
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Hmmm was thinking just the same..... I have wrecked a gearbox by power feeding the saddle into a 4 jaw on the edge of its swing (I was at the time roughing with one machine and finishing with another must learn I'm not a woman)....... the chuck shattered and two shafts and a set of gears lost there teath... however on being rebuilt the mandrel was unharmed.......
as fluffy said........ even if you had run out at the thick end this could be corrected by machining the face.....
I have a feeling tho hes clocked the chuck body tho......
as fluffy said........ even if you had run out at the thick end this could be corrected by machining the face.....
I have a feeling tho hes clocked the chuck body tho......
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We took the chuck right off and just turned the lathe on without a chuck and he DTI'd the spindle that the chuck screws onto. The needle was moving up and down. Ive had a better look at it and i think it could be the bearings in this pic below? you can feel a tiny bit of play in them when the spindle is 'wiggled'
ahhhh spindle bearings are quite likely, especialy if its done jobs like knurleing....
Yes, the check is to put the dti on the spindle where the chuck screws (the spindle nose), and wiggle the shaft, more than say 0.003" of play is probably out of spec. Thats the tolerance for a southbend which had plain spindle bearings. If you can feel a perceptible clunk, possibly they're really worn. Lathes are supposed to be oiled religiously, and I cant see any oilers present for the bearings in your pics, nor grease zerts (which actually take oil usually)
If it is just the spindle itself bent, its possible to correct the run out in the chuck baseplate itself.
You have to very very carefully turn the chuck->backplate register in situ, without making it undersized, then for that machine anything bolted to it will be true. You need to verify the state of the headstock bearings first though.
Also most lathe bearings are adjustable in one way or another to allow you to take up the play when they begin to wear. This varies from lathe to lathe in method though.
If it is just the spindle itself bent, its possible to correct the run out in the chuck baseplate itself.
You have to very very carefully turn the chuck->backplate register in situ, without making it undersized, then for that machine anything bolted to it will be true. You need to verify the state of the headstock bearings first though.
Also most lathe bearings are adjustable in one way or another to allow you to take up the play when they begin to wear. This varies from lathe to lathe in method though.
Oh, and don't do it while rotating under power! Measuring devices (especially sensitive ones) are made to measure stationary or extremely slow moving objects.
Procedure is to check the thing while rotating it by hand to various points. You can mark one of the gears or something with a felt, spin it round a few times by hand and repeat the test, this will tell you if its CONSISTENTLY bent in the same place and if your test is valid. Then maybe spin it up under power, make a cut on it, then repeat. If it doesn't repeat, look at the bearings.
Procedure is to check the thing while rotating it by hand to various points. You can mark one of the gears or something with a felt, spin it round a few times by hand and repeat the test, this will tell you if its CONSISTENTLY bent in the same place and if your test is valid. Then maybe spin it up under power, make a cut on it, then repeat. If it doesn't repeat, look at the bearings.
It depends on what type of bearings it has been fitted with. Ball or taper bearings can be just swapped in and adjusted, plain bearings will require either you obtain a new set (probably less likely) or find someone with a nice lathe to make you a new set, then final ream them in situ to size...
Sometimes the plain bearings have a adjustment, sometimes theres a way to nip them tighter, or theyre tapered slightly and you can adjust a coller to change the preload.
Heres where you need to find out what type of lathe it is exactly, and find some other owners. Old stuff is usually the focus of a group somewhere in the world who know how to adjust and the problems of that particular beastie...
Before you get into all that, you could do with measuring how bad they are. If theyre just a bit loose, you can accept that as your not going to be making any high tolerance components on it right no, and the runout could be something else (like the spindle nose bent slightly)
Sometimes the plain bearings have a adjustment, sometimes theres a way to nip them tighter, or theyre tapered slightly and you can adjust a coller to change the preload.
Heres where you need to find out what type of lathe it is exactly, and find some other owners. Old stuff is usually the focus of a group somewhere in the world who know how to adjust and the problems of that particular beastie...
Before you get into all that, you could do with measuring how bad they are. If theyre just a bit loose, you can accept that as your not going to be making any high tolerance components on it right no, and the runout could be something else (like the spindle nose bent slightly)
