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10k spindle bearing clearnace

Englishwheeler

Plastic
Joined
May 27, 2017
New 10K owner here. Also new to South Bend lathes. I got a decent lathe locally and am stepping up from my Chinese 9x20 lathe.
I purchased a manual and proper lubricants and decided to do some maintenance before using the lathe.
First up was setting the spindle clearance. I followed the South Bend procedure but am unable to get .0007-.001" clearance on my back bearing and still turn the spindle freely. Right now I'm at about .002". The front bearing is right at .001".
Is this a problem? Is there something I'm missing on the rear?

Thanks for any help.
 
most likely you are pulling too hard and flexing something and getting a false reading.

How you mount the indicator matters too, IMO it should be mounted to the headstock casting to isolate things.
 
Thanks. I will try again and see.

The other thing I notice is that I get all kinds of varying run out numbers from the chuck. I get as much as .030" TIR on a precision ground rod out at 6". Then I re chuck it and get .010". I can notice light between th jaws and the rod. I wonder if the chuck/jaws are worn out?
 
.002 at the back is not a job killer.. if taking it apart again you might blue it up to see the cap is coming down straight.Perhaps a shim bug had it at little tilt.and so to get .001 may be near impossible.. .002 at front and back is not a big deal....

You would be very lucky to get .002 or even .005 out of a chuck holding.. Out at 6 inches even in a 4jaw your lucky to run .005 at 6 inches out with zero at close.

Using a chuck you see you have enough "take off" stock to make finish size . Then do all your turning from one end. so the part is as good as the machine.. not the chuck..

Parts that need work at both ends are good to finish between center..Good to know to be quick and comfortable with centers.
 
.....
First up was setting the spindle clearance. I followed the South Bend procedure but am unable to get .0007-.001" clearance on my back bearing and still turn the spindle freely. Right now I'm at about .002". The front bearing is right at .001".
....
If it has .001 on the back and .002 on the front everywhere it will rotate freely.
Somewhere you are not measuring is tight.
So you may have to go looser in the area you check to get the .001 in the area you do not.
Nothing in this real world is straight, true and square. It's never like the drawings in a book or CAD system where the world is perfect.
Free rotation is a must followed by temp rise in the spindle bearing area when run at max speed for an hour.
Bob
 
If you put a 2x2 pry and lift the front and the back to get perhaps .002 at each the spindle is fairly close..close enough to do good work. The pry pull should be little more than what it might take to lift the chick ..Run it at 1000 for a time and get a little or no heat is good.. a little heat is ok. Be sure front and back are getting OIL.
Focus on getting a better chuck.

Some day you have plenty of time you can blue it up the bearings.. take out .002 and see if and where it marks blue with hand turning..Getting it down to .001 likely wont even be noticeable in the work.

You tube.. doing a lot of high speed work and .oo2 is best IMHO.
Southbend Spindle Bearing Clearance Adjustment - YouTube
 
Thanks again guys. I'm new to the forum stuff so I haven't figured all of it out yet on posting stuff.

My front bearing clamp bolt is cinched down fairly well. At .002" clearance in the rear I have to have the bolt somewhat loose or the spindle won't turn freely. I am wondering if it would be best to add a .001" shim so I can tighten the bolt more?

Also, michiganbuck, I think a new chuck is in order for sure. I looked at the Shars chuck and may get one. I have a hard time believing that I can have much less runout on my Harbor Freight 9x20 lathe than on this South Bend lathe. That's why I'm concerned. But I have less than .001" at the spindle when the chuck isn't mounted.

I've never mounted a new chuck before. On my current lathe I've used the same chuck for 8 years and have never taken it off. So all this is pretty new to me.

I tested runout on the 10k backplate and it was .001". The chuck was the same. The face of the chuck wasn't off either, so I have to believe the issue is in the jaws or the internals of the chuck.

Sorry for the novice questions. But I really appreciate the help. I realize I'm asking two things in one post.
 
Are you loosening the expander screws before you cinch down the bearing bolts and then retightening them?

There are a lot of members here that are likely in your area, the guys here are very helpful fellas and one might come to assist you if you ask.
 
Are you loosening the expander screws before you cinch down the bearing bolts and then retightening them?

There are a lot of members here that are likely in your area, the guys here are very helpful fellas and one might come to assist you if you ask.

No. I have the expanders tight before I do any adjustment.
 
That is probably the problem then, you must slightly loosen the expanders first before cinching the bearing bolt.

When you retighten the expander screws a good rule is to only use your thumb and index finger to turn the screwdriver...it doesn't take much...the screws are small and can strip and/or break easily.
 
Thanks again guys. I'm new to the forum stuff so I haven't figured all of it out yet on posting stuff.

My front bearing clamp bolt is cinched down fairly well. At .002" clearance in the rear I have to have the bolt somewhat loose or the spindle won't turn freely. I am wondering if it would be best to add a .001" shim so I can tighten the bolt more?

Also, michiganbuck, I think a new chuck is in order for sure. I looked at the Shars chuck and may get one. I have a hard time believing that I can have much less runout on my Harbor Freight 9x20 lathe than on this South Bend lathe. That's why I'm concerned. But I have less than .001" at the spindle when the chuck isn't mounted.

I've never mounted a new chuck before. On my current lathe I've used the same chuck for 8 years and have never taken it off. So all this is pretty new to me.

I tested runout on the 10k backplate and it was .001". The chuck was the same. The face of the chuck wasn't off either, so I have to believe the issue is in the jaws or the internals of the chuck.

Sorry for the novice questions. But I really appreciate the help. I realize I'm asking two things in one post.
* bronze and cast iron bearings have different clearance one is 0007 to .001 and the other is something like .001 to .002.. check this out because i don't remember exactly

*Just read a PM post from sieve-L in Germany who said he got .006+ or so run out from a new Shars chick...?

Perhaps some PM guys buying a Shars chuck might give some feed back as what to expect from them. I have never bought one so don't have a clue.

OT steve: [I'm happy you folks did well with Shars products, but I was not so lucky when I bought a 4jaw scroll chuck 3 months ago. My run out was between .006 and .012". I tossed it in the scrap bin in the shipping box. It was too expensive to return.]
 
Ok, IMO just about any 3jaw chuck with 2 piece jaws will do so here are my choices on a shoestring budget.

SHARS 5" 3 Jaw Self Centering Scroll Lathe Chuck 2 Pc Reversible Jaws NEW | eBay

next up in the 3 jaw category would be this one, and this is the type I prefer because it's a front mount which lets you do the poor mans adjust true thing which also IMO is better than a real adjust true chuck, you can still do this with the Shars chuck too with a shortened leg Allen but it's easier if the chuck is front mount.

http://www.ajaxtoolsupply.com/at3jawunirbo.html

Where you might feel overwhelmed is fitting them to a backplate so maybe the Shars chuck will appeal to you more because they sell a ready machined plate that just needs final fitting.

5" Fully Machined Threaded Back Plate with 1-1/2 x 8 TPI for 3 or 4 Jaw Self Centering Lathe Chucks

The 4 jaw is easy, the nicest budget 4 jaw I had was by far this one-
Vertex, Chuck, 4 Jaws, Independent, 16 mm (6 inches), VKC-6-F, 52-222 | eBay

IMO the 4jaw is more important than the 3 jaw, because with 2 piece jaws and using the poor mans technique any 3 jaw will be ok but with a 4 jaw you really need something decent because at some point you will want to do an offset, like making a cam and although any 4 jaw can be adjusted to zero run out at the jaws the ultra cheapest will not hold straight once you move out a few inches, my inexpensive Vertex 4 jaw would.
 
The chuck makes the lathe.. Many chucks boast .0005 and many .003.. I know .003 is not a job killer but TIR is one thing and wobble is another. Wobble it that out 4" or so out of the chuck. Even a 4 jaw is crap with having wobble.

Quality of materials in another big issue.. three years down the road is the low ball chuck going in the dumpster?
Looks like the low ball $200, mid range $400 .. good chuck $1,000..

Here at PM we should know more about chucks..Steve said a new xx chuck was so poor it went into the dumpster after first try.. guess based on that I would go to the $400 chuck for hobby use and the $1,000 for jobber work.

Yes we need more reporting from PM members on new chuck performance.

Sorry to say I have never had a .001 lathe chuck but have had .001 chucks mounted on grinders.
Most of the lathes I have used .. a close job would go in the 4jaw, steady and/ or centers.
An adjust true gets around TIR but does not help wobble.

*Think needed: PM thread with no opinions but lathe test reporting. Bought a new XX chuck and it ran xx at close and xx out 4"

I posted the Travers/Gator chuck just based on their advertising .0005.. I have no idea if it any good .,may just be crap ..or good?.
 
So much to consider! Lots of great info!
I do primarily motorcycle fabrication and metal shaping. My lathe work is mainly to making things I need like bushings, fittings, dollies for shaping, etc. I don't do aircraft or production work on the lathe. I'm not sure $1,000 for a chuck is a consideration. $400 is better.
While I want to have nice reliable equipment, I don't want to equip myself to make space shuttle parts.

Btw, I readjusted my rear bearing on the lathe and still have the .002" clearance. But now I'm able to tighten the pinch bolt and still have a free turning spindle. Guess that's as best as I will get.
Cleaning up the cross slide and compound now. Hope to be running soon.

Cleaned the chuck and reinstalled the jaws. Still have the varying run out when clamping a piece in. Clamp once and it's .030" at 4" out. Remove and reclamp and it's .006". That's a little frustrating but guess I can make it work until I get a new chuck.
 
just an odd ball check but mark tightening holes 1 2 3 and see if one is better. 4" is fairly far out so tail center when you can.. perhaps make a tail female cup center to support non centered parts..perhaps use the tail cup center to located a chuck held part, some time you can tighten in a poor chuck then with a brass knocker bump the part to better(less) run out. some times snug tighten and knock a little. Very often I would just hand roll the part with looking at the tool bit for close and far to the part rather than setting an indicator.. After getting used to this it is easy

Yes think you should figure perhaps the best chuck in about the $400 group..I thoght Atlas was better than .003 ..it is a pretty good chuck..but .0005 is better.

Still the lathes I used .003 was a good day.and I was quick to go to centers.
 








 
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