Set thru type chuck

[swd]

My first cuts go .020", .010", .005". There just isn't that much material on the first cut even at .020".

 

[Cloudrepair]

At first I used a 6" buck 3 jaw set true and an out board spider with brass tips and the copper wire on the barrel. I would dial it in to .0002 or better and start taking cuts and check it again before finish cuts it always seemed to move maybe only .0005 but enough it bugged me.
Then I saw a setup I think it was bamban with the ball bearing screws and feet so I turned some set screws to a .1875 radius and made the feet with a ball mill on a inboard and outboard cathead/spider and the problem went away no more movement at all.
I beleave it is do to a little bend or torque in the barrel from dialing in without keeping the barrel in a free state then when a little force is applied in a perpendicular way it wants to move to a free state again so you get a little slip.

 

[Danny1788]

At first I used a 6" buck 3 jaw set true and an out board spider with brass tips and the copper wire on the barrel. I would dial it in to .0002 or better and start taking cuts and check it again before finish cuts it always seemed to move maybe only .0005 but enough it bugged me.
Then I saw a setup I think it was bamban with the ball bearing screws and feet so I turned some set screws to a .1875 radius and made the feet with a ball mill on a inboard and outboard cathead/spider and the problem went away no more movement at all.
I beleave it is do to a little bend or torque in the barrel from dialing in without keeping the barrel in a free state then when a little force is applied in a perpendicular way it wants to move to a free state again so you get a little slip.

I haven’t tested my six jaw set tru enough but my ball bearings setup like yours is rock solid. My six jaw is so fast and i get equal results from the same reamers I guess it’s close enough. Not a good comparison I know

 

[coontz74]

At first I used a 6" buck 3 jaw set true and an out board spider with brass tips and the copper wire on the barrel. I would dial it in to .0002 or better and start taking cuts and check it again before finish cuts it always seemed to move maybe only .0005 but enough it bugged me.
Then I saw a setup I think it was bamban with the ball bearing screws and feet so I turned some set screws to a .1875 radius and made the feet with a ball mill on a inboard and outboard cathead/spider and the problem went away no more movement at all.
I beleave it is do to a little bend or torque in the barrel from dialing in without keeping the barrel in a free state then when a little force is applied in a perpendicular way it wants to move to a free state again so you get a little slip.

Got any pictures of this setup?

 

[pat fulghum]

True bore alignment system (aka TBAS) with 6 jaw Chuck.

Nothing to compress, and it just doesn’t move

 

[skeeljc]

Anybody ever use a shars chuck? Says theyre certified to .0005tir and are a third or more off a gator or buck or bison

I have Shars 6" and 8" three jaw chucks on a 14" lathe with D-4 mounts. Great chucks. Both are within .002" TIR. Mine are two piece jaws because I use a lot of soft jaws.

 

[bibsmachine]

True bore alignment system (aka TBAS) with 6 jaw Chuck.

Nothing to compress, and it just doesn’t move

I agree the TBAS is a very good system.

 

[coontz74]

I agree the TBAS is a very good system.

I’d love to have one, but I’d need a go fund me page to do it....