Locking Threaded Chucks

[YYCHM]

Spent the day prepping this backplate that I sourced from @140mower (Thanks Don).....

Had to turn the registration down and re locate/drill the mounting holes. Then I turned the spigot/boss down to accommodate a 2.25" clamping collar. Tomorrow I'll source a 1/16" thick slitting saw to slot the spigot/boss with and will see if I can set her up on the mill using a angle plate. I'm left hand challenged right now and I don't think I can mount the RT due to it's weight. We will see.

@dfloen will 1/16" be wide enough? Your images look a lot wider than that.

 

[Mcgyver]

I had a look at the set up on a Schaublin, the clamp is there, but there are not slits in the backing plate just slits in the ring. That bore is the is the surface that mates with the shoulder of the spindle is the critical register for the chuck, so not crazy about machining it. I guess it would depend on how much clearance there was as to whether you had to or not..

 

[YYCHM]

I had a look at the set up on a Schaublin, the clamping is there, but there are not slits in the backing plate just the ring.

View attachment 21140

How the heck does that arrangement work?

 

[Darren]

1/16" will be fine. It doesn't need much. It should be tight before you clamp it.

 

[Mcgyver]

How the heck does that arrangement work?

Agreed, its not intuitive, but it works. I assume the ting tightens up on the plate which should have almost no clearance to spindle and it moves the plate enough to clamp.

 

[YYCHM]

Ha.... don't know why I was thinking RTs and angle plates..... Over thinking things again

Stuck her in the vise and used machinists squares to align things. Thank god for a PF... it was lots of back and forth and plenty of cutting fluid. Had the VFD set to 10 hz

Seems to work.... as to how well I won't know until I mount it with a chuck and really reef on it

 

[YYCHM]

She ain't budging.......

Runout isn't bad either, 0.002-0.004 depending upon what you put in the chuck. This chuck has always run about 0.005. I think it's the jaws as the chuck body indicates next to zero runout.

 

[YYCHM]

Was doing some turning today that wasn't going well at all......

Discovered the chuck runout had degraded to 10 thou . It should have been no more than 5.

Ends up where you tighten the locking ring on the backplate boss can pull things 5 thou out of alignment

 

[RobinHood]

Ends up where you tighten the locking ring on the backplate boss can pull things 5 thou out of alignment

Could be a mismatch of bores/fits somewhere between the critical surfaces. If you have a bit of adjustability on the chuck back plate, you might be able to remove most of it after you install the chuck. Bit of a drag having to do it each time, but might be worth it when you turn more critical parts. OTOH, if you have enough stock for removal, the runout won’t really matter if all the surfaces get machined in one set-up.