Bison chuck WAY out

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #1

I have a 1937 SB model C (model A conversion). I just got a 6" 2 piece 3 jaw Bison chuck for it. The chuck is almost 10 thou out of center.. That seems a bit much. Are new chucks supposed to be ground? Should I dust the ID with a boring bar??

 

I

iwananew10K

Diamond

Joined

Sep 12, 2010

Location

moscow,ohio

• Dec 12, 2016

• #2

Did it come mounted on a backplate? And if it did was it done by Bison?

How and what are you measuring?

 

T

toolnut

Stainless

Joined

Aug 3, 2005

Location

Kingsport, TN

• Dec 12, 2016

• #3

Is it an adjust true design? Sounds like it might be.

 

G

gadget73

Hot Rolled

Joined

Mar 8, 2016

• Dec 12, 2016

• #4

How accurate is the backplate's register? I'd probably pull that off and indicate it to verify its right. If the chuck isn't centered on the plate its going to have runout. Also depending how loose things are with the register and bolt holes you may be able to tap it around some and get it to run more true.

 

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #5

yes it came mounted by bison.. Its a 1-1/2x8 back plate.. and I'm measuring with a piece of milled round stock and a dial..

 

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #6

Its a bison 3 jaw with 2 piece jaws...

 

T

tobnpr

Hot Rolled

Joined

Sep 27, 2015

• Dec 12, 2016

• #7

What's your spindle TIR?

 

I

iwananew10K

Diamond

Joined

Sep 12, 2010

Location

moscow,ohio

• Dec 12, 2016

• #8

How about the OD of the chuck body?

 

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #9

sorry,, excuse my lack of experience. whats TIR?

 

K

kitno455

Titanium

Joined

Jul 9, 2010

Location

Virginia, USA

• Dec 12, 2016

• #10

Total indicated runout.

allan

 

K

kitno455

Titanium

Joined

Jul 9, 2010

Location

Virginia, USA

• Dec 12, 2016

• #11

Don't touch the chuck with a boring bar. You sound like a bull getting warmed up for the china shop...

allan

 

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #12

the only place on the body i have an uninterrupted edge all the way around is the OD of the back plate. Which is about 7 or 8 thou out as well.. maybe my spindle is not spinning true??

 

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #13

hahahaha,,, Don't worry,, Im not.. Im not the type to haul off and do stuff like that unless its 100% accurate info to do so.. I have learned my lesson with this type of stuff... Btw.. Where on the spindle would I put the dial to measure run out??

 

K

kitno455

Titanium

Joined

Jul 9, 2010

Location

Virginia, USA

• Dec 12, 2016

• #14

If the back plate was not turned on your lathe, there is no reason that either it, or the chuck would run true. You need to make sure the backplate is seated well against the spindle and clean up the OD and registration shoulder where the chuck seats.

allan

 

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #15

Sorry again. But where is the registration shoulder? I have been using a lathe for 7 years but never had to replace a chuck.. So this is new to me..

 

Spyderedge

Titanium

Joined

Aug 28, 2013

Location

NY

• Dec 12, 2016

• #16

Bluecollarirons said:

hahahaha,,, Don't worry,, Im not.. Im not the type to haul off and do stuff like that unless its 100% accurate info to do so.. I have learned my lesson with this type of stuff... Btw.. Where on the spindle would I put the dial to measure run out??

Click to expand...

On the unthreaded section by the shoulder, or inside the taper (however the taper can have wear in itself)

Check spindle runout, then check backplate shoulder and face runout. If all good, make sure the chuck seats tightly on the back plate. If it shifts radially any ammount, it's probably by design so you can lightly *hammer* it true with a soft face mallet to get zero runout. If it is however tight, it's somewhere in the chuck.

 

I

iwananew10K

Diamond

Joined

Sep 12, 2010

Location

moscow,ohio

• Dec 12, 2016

• #17

there should be 2 uninterrupted areas you can indicate, just in front of the pinions and just behind them...not much but enough to get an indicator point on.

Do indicate the spindle without the chuck too.

Make sure it's all nice and clean before you remount the chuck, check the backplate threads to for a stray chip.

 

Bluecollarirons

Plastic

Joined

Apr 23, 2010

Location

Portland OR

• Dec 12, 2016

• #18

oh ok.. I got it.. Its the shoulder where the chuck and back plate butt up.. So I face that off a hair?? On just the back plate or chuck body too?? I have a 4 jaw to fit the chuck body

 

K

kitno455

Titanium

Joined

Jul 9, 2010

Location

Virginia, USA

• Dec 12, 2016

• #19

Bluecollarirons said:

Sorry again. But where is the registration shoulder? I have been using a lathe for 7 years but never had to replace a chuck.. So this is new to me..

Click to expand...

Assuming the chuck and backplate can be separated, you pull the screws out, and look at the backplate under the chuck. There will be a raised area that centers the back of the chuck.

allan

 

J

James Lederer

Hot Rolled

Joined

Mar 19, 2012

Location

Southern Wisconsin

• Dec 12, 2016

• #20

Are there three screws on the front face of the chuck, and then three screw around the outside at the rear of the chuck close to where it meets the backplate?

If so, you have a set-tru chuck. Chuck a piece of ground stock in the jaws, slightly loosen the three screws on the front face so they are just lightly snugged down, and then adjust the runout until it disappears with the three screws around the outside. Then tighten up the three screws on the face of the chuck.