----- Original Message -----

From: Jim Bonner

To: daltonlathes@...

Sent: Friday, July 28, 2006 7:54 PM

Subject: [daltonlathes] Re: Chuck Mounting Question

Hello John,

I'll try to answer some of your questions. You may be able to use
the backplate off your 3 jaw chuck if the diameters are larger than
the finish diameters required for the 4 jaw chuck. If you are not
aware of it, there are two outside diameters on the flange. The one
that has the mounting bolts and a smaller one that fits into the
counterbore (recess) in the chuck. ( if you haven't removed the
backplate from your 3 jaw, be sure to index mark both the chuck body
and backplate flange before disassembly. )

The spare backplate that you mentioned with the thicker flange may be
a new one that hasn't been fit to a chuck. This one may be the
better choice.

The reason that it's best to fit the backplate on your own lathe is
so that the backplate recess that fits into the chuck counterbore
will be concentric and square to YOUR spindle. I don't know if the
dimensions for the backplate will come with a new chuck. If not, you
will have to measure the chuck counter bore dia and depth then cut
the backplate to fit.

Also, on a 4 jaw you will have to drill and tap the holes in the
backplate.

hope this helps, Jim

--- In daltonlathes@yahoogroups.com, "bomber60015" ...>
wrote:
>
> Good Morning Gents
>
> I've another new guy question –
>
> Before I get to it, thanks to all of you who've been kind and
> patient with my previous inquiries – while I'm sure they are
> elementary to you folks, they were a bit daunting to me – I
> appreciate your kindness and patience.
>
> O to the question – I've gotten to the point that the 3-jaw Union
> Chuck that came with the lathe is now the weakest link in the
> accuracy chain (previous weakest link wsa me ;-} ).
>
> The scroll and backsides of the jaws are very worn (no surprise –
it
> doesn't look much younger than the lathe), and it's only in the
> accurate ballpark at one diameter setting (darned near maxed out).
>
> I've decided to spring for a decent 4-jaw chuck – I read, with
> relief, though the spindle threads on these old nails IS oddball (I
> was scratching my head wondering why I couldn't seem to find a
> commercially available chuck that would mount up easily).
>
> Is there a reason I couldn't use the back plate off the Union chuck
> to mount the new 4-jaw?
>
> Also, among the rusty greasy bits that come with the latch is what
> appears to be a spare back plate. It mounts on the spindle very
> nicely, but the flange (is that the right term?) is thicker that
the
> one on the Union chuck, and is not drilled for any mounting
> hardware. Could THIS be used to mount the new chuck?
>
> Lastly, I've seen references on the board here to getting a back
> plate and doing the mounting to the chuck on your own lathe. While
> this makes sense (getting maximum accuracy), I have no idea how to
> go about doing this . . .. any pointers?
>
> Thanks, in advance, for any assistance you may be able to render!
>
> John Rosberg
>