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South Bend 10L spindle excessive side to side play?

bikesandcars

Plastic
Joined
Mar 14, 2021
My 10L spindle may have excessive side to side play.

I trued up my Buck adjustable 3 jaw chuck (within .001 - ish).

I noticed I can simply push the chuck back and forth from front to back and give several thousandths of play. The face-bolts on the jaw are tight. The play is magnified at the end of the chuck, but also measurable closer to the spindle. When I do this I can hear a faint clunking sound.

Is this normal or is there an adjustment for it?

Video I just took:
 

GenePoole

Cast Iron
Joined
Dec 8, 2012
Location
St. Louis, MO
Is the play in the chuck or the spindle? Can you remove the chuck and do the same check? If so, then it would seem to be loose spindle bearings, otherwise, any number of things in the chuck/jaws/backplate/camlock.
 

wood2steel

Aluminum
Joined
May 17, 2013
Location
georgia
Gene is absolutely correct. Get the chuck out of the way and make a good assessment of the bronze bearing fit. Smaller machines were notorious for bearings wearing egg shape @ 9:00 due to constant heavy cuts on small machines. Unfortunate, your bearing shims may only only resolve a portion of that problem. You will be plagued with constant chatter otherwise. Good Luck
 

bikesandcars

Plastic
Joined
Mar 14, 2021
Thanks Gents! Too much desk work, no machining going on, finally circled back.

I removed the chuck and used an aluminum rod inserted into the spindle center with me pushing / pulling to check the play. I measured off of the side of the spindle where the chuck attaches

Z axis (axis of rotation): (+-) 0.006" play !!! that was the clunking sound. Snugged that up (also looking into replacing with bearings)
X axis (towards / away from operator): +- 0.003" (about .0015 away and the same towards)
Y axis (Up and down): Up 0.001, down 0.000

My take-aways:
The chuck is reasonably tight
The distance away from the spindle amplifies the deflection (duh).
It appears that my bearings are egg shaped.

So, now what to do about it?
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
Your bearings may or may not need to replaced. I don't really know until I see them, or you exhaust you adjusting procedures for tightening them. But I can tell you those bearings are not truly round, the way a normal solid bushing is.

I don't fully understand what your calling Z axis, and if that is still a problem for you. There are several threads here for adjusting those bearings, as well as some info in South Bend manuals. The one thing to becareful of is the expanaders, be sure to loosen them, or follow instructions before removing bearing cap if you choose to do so.

Looking at chuck face from tail stock. I like to take measures and readings between 6 and 12 oclock(up and down), and between 3 and 9 oclock(front to rear). And spindle end thrust, toward and away from tail stock.

End thrust to .0005"-.001"

Bearing oil clearance to about .001", give or take a hair. But that would be for both head stock bearing caps, at both 6 & 12, and 3 and 9 oclock readings.

Another note. You have a cam lock spindle. Is it D1-3 ? Your current set up and chuck look heavy for 10" South Bend. Plus its extended pretty far. Sure its doable, but that could improve. If it is D1-3, find a 4 jaw for a Monarch 10ee. Most 10ee's have a short bed length. So the length of chucks designed for them is somewhat shorter and lighter as well. I think one of those would help you quite a bit on deflection.

You may like a 3 jaw, but a 4 jaw will change your life when you start using it, and dialing stuff in.
 








 
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