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Working on my South Bend 9C

Ok so that was easy except for my ridiculous magnetic base.
Lathe is cool the first check showed about 2.2 so I tightened the adjustment bolt about 10° and the runout changed to about 1.5. The spindle would stay where I put it ie. if I lifted up it stayed up (more or less)and when I pressed down it stayed down.
I ran it for a few minutes at fast no load and it is still it same old silky smooth quiet self.
My lathe came to me from a friend who was a master machinist who had inherited it from his father, it was his basement lathe for small special jobs.
 
Garyt, is your SB9 a Junior, AKA heavy 9?
I think they have headstock shell bearings, not the bored headstock of the workshop type 9.
But i don’t really know, i’ve never seen a SB Junior 9.
BTW, nice Europa.
 
My lathe is not a heavy. I have had the spindle out a few times (don't ask) it is definitely a cast iron bearing .
Thanks, I like the Europa fun to drive turns heads wherever I go. They are such a rare car.
 
Golem Pens said:
Not a three jaw, ER32 collet chuck.
Click to expand...

Whatever kind of chuck it is, @140mower's advice still applies. When you turn something that has a lot of runout, the act of turning eliminates the runout. That what lathes are designed to do.

If you do your order of operations wisely, you will end up with nice concentric low runout parts regardless of chuck runout.
 
That helped..... okay, something to look at is the registar on the chuck, it should just barely squeak over that portion of the spindle when it is tightened up.....
Make sure the threads are clean of any chips and burrs.....
Confirm that the collets are sufficiently deburred as well. This is an ongoing problem with offshore tooling......
Ensure that you are seating the collet into the nut correctly prior to installing in the chuck.....
Lastly on my list, these wanna be tight, I am not sure the exact torque. But tighter than you probably think.....
 
So for workflow on say a pen cap, what I currently do is below. This is carrying over from my operations on the wood lathe.

1) Using appropriate collet to hold material rod - drill, ream, and tap the internal bore.
2) With a different collet to hold an internal mandrel onto which the cap threads - shape the outside.

With that, if I have eccentricity, if I'm braining right... That's not really an issue in step 1! But then in step 2 I end up with eccentricity between the inner bore and outside surface.

The other parts are a bit more involved.
 
Can you indicate on the inside taper of the chuck without a collet? If that has run out then there is no chance to get it straight
 
140mower said:
That helped..... okay, something to look at is the registar on the chuck, it should just barely squeak over that portion of the spindle when it is tightened up.....
Make sure the threads are clean of any chips and burrs.....
Confirm that the collets are sufficiently deburred as well. This is an ongoing problem with offshore tooling......
Ensure that you are seating the collet into the nut correctly prior to installing in the chuck.....
Lastly on my list, these wanna be tight, I am not sure the exact torque. But tighter than you probably think.....
Click to expand...
Everything is clean (since I just tore it down), and these are collets I've used well before, but will give them all a once over!

Chuck to spindle registration, hmmm
 
Golem Pens said:
1) Using appropriate collet to hold material rod - drill, ream, and tap the internal bore.
2) With a different collet to hold an internal mandrel onto which the cap threads - shape the outside.
Click to expand...

Ya, that's not a good process. It might be necessary though.

Ideally, the part would never be remounted from beginning to end.

That may not be possible for your Pens. Emphasis on "may not".

But you may be able to come up with a different mandrel that is more concentric on its own independant of the chuck. The key will probably be indexing and consistent mounting.
 
I made a er32 collet chuck. First an internal thread to fit the spindle. Then complete the rest of the features with the chuck blank on the nose of the spindle.
I think more luck than good management but it runs very true and very repeatable.
 
Garyt said:
I made a er32 collet chuck. First an internal thread to fit the spindle. Then complete the rest of the features with the chuck blank on the nose of the spindle.
I think more luck than good management but it runs very true and very repeatable.
Click to expand...

Good point Gary. There is more than one way to get concentricity.
 
Golem Pens said:
The lack of material strength makes it tricky to do both sides without support I think.
Click to expand...

That's true. But there are tricks for that too. If you try to make a needle in multiple passes, it will collapse. But if you make it in one pass, there is no load on the needle so it does not collapse. That same principle may apply to your situation.
 
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