On 2008-07-31, Ignoramus25244 wrote:
Won this on ebay. This backplate should fit my lathe. It did not cost
much, so I am sure that I can use it for various purposes, whatever
they might be.
http://cgi.ebay.com/ws/eBayISAPI.dll...m=190239479425
And my question is, how hard is it to find a 5C collet adaptor/chuck
that would fit this, perhaps with some machining. I am not sure what
is the exact name of the thing that I would be looking for. "plain
back 5C chuck" or something?
Bison makes one -- actually two. One with rigid coupling to the
backplate and one with the adjust-true feature.
I think that you can at least turn the step on the backplate
down to fit the Bison 5C collet chuck -- but I find myself wondering
*why*? A L1 spindle nose is certainly large enough to have sufficient
spindle bore to accept an adaptor and a drawtube -- ideally a lever
closing drawbar for convenience.
The collet chucks have three major disadvantages and one minor
in my opinion which is why they are normally used only on lathes with
too small a spindle bore to accept a drawtube style closer.
1) The extension takes up some of the distance between the spindle
nose and the tailstock center or drill chuck.
2) Because of that extension, there is less rigidity.
3) The runout is typically worse on this than on a proper
adaptor -- especially if you don't get an adjust-tru style
collet chuck.
4) (minor disadvantage) -- it takes an amazing number of turns of
the key to change one collet for another.
However -- if you *really* want the collet chuck, one place which
carried them (and from which I have bought Bison chucks and backplates
in the past), let's see what they have at the moment:
URL: http://www.brassandtool.com/Chucks-Collet.html
7-862-0501 5 inch 3/64 to 1 1/8 10 lbs. $ 350.00 (backplate mount)
7-862-0505 5 inch 3/64 to 1 1/8 12 lbs. $ 495.00 (set-true -- you'l
have to modify the backplate
quite a bit more.)
There is also one for 16-C which would be a better ftt for the
backplate which you have, but 16-C collets -- while they hold a lot
larger workpiece, are much more expensive. 5C can be dirt cheap because
they are so common.
On this page:
http://www.brassandtool.com/Backplate-Adaptors.html
you can find your backplate:
7-879-083 8 inch L1 $ 150.00
While they have direct-mount versions of the collet chuck, there
is none for any of the L series spindle noses, and certainly none for as
large a spindle as the L2 -- because the spindle chuck is really a poor
choice for such a large lathe. It is intended to adapt small lathes to
being able to use 5C collets, and is normally not needed for one as
large as you have.
Enjoy,
DoN.
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