I have a small table top mill (Grizzly), a rotary table and a four jaw chuck
I'd like to fit onto the rotary table. The chuck has no through holes
through which I can access the tee nuts to hold it to the table. Only blind
holes on the back. The chuck is also the same size as the rotary table, so
it covers the tee slots completely.
Easy solution: Make a round base with a recess turned around the side where
I can reach in with a wrench and tighten bolts into the tee nuts.
But I'm thinking; Is there a way to tighten a tee nut with a cam, wedge or
whatever from the side of the adapter plate? The idea here is to keep the
adapter as low profile as possible.
Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com
My 6" table has a 6" adapter for my 6" 4 jaw chuck from my lathe . I cast
a blank in my aluminum foundry with the lost foam process and machined it
matching slots in the table so it can be centered easily . This also allows
centering with the chuck jaws ... I've used this setup to machine gears , 3
of which now reside in the QC box on my lathe .
On Fri, 17 Jan 2014 16:48:46 -0800, "Paul Hovnanian P.E."
Is there any reason why you don't or can't just drill holes through
the chuck so you can bold down through it? Is it because of hollows in
between the jaws on the underside of the chuck? You could drill and
counterbore holes very close to the perimeter of the chuck, so that
the counterbore for the screw head doesn't quite break through the
O.D. of the chuck.
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Of course! But there are 'costs'. You'd have to slot the bolts,
foregoing strength. You'd have to 'collar' them to make them captive to
actuator wedges... you'd... Oh... you know... it goes on and on.
Why not just build a couple of adaptor plates that DO extend out past the
perimeters of the things you want to bolt down? Bolt one to the back of
the chuck using the existing blind holes, then bolt the plate to the
table (rotary or mill table) with tee nuts/bolts as usual for fixturing
parts. If necesary, duplicate the method on the face of the rotary.
'Hate to say it, but I think I spend more time mounting stuff than I do
Easier solution -- drill and counterbore into the chuck body the
holes for your bolts to the Tee-nuts. (Start with a turned plug which
fits the center of the table and the chuck to hold it concentric while
you drill the holes. Three or four radial T-slots in the table? If
four, put them about half-way between the jaws, and pretty far out
towards the OD. With three T-slots, put one half-way between two jaws
and check that the others clear the jaws and their ways and screws.
Having the holes the same radius for each bolt will keep the
chuck balance correct for use on the lathe (which I presume you consider
The only time this might not work would be if you happen to have
one of the fairly rare *universal* four-jaw chucks (jaws moved by a
scroll plate like in a 3-jaw chuck). There, the through holes would be
likely to hit the scroll plate, so your adaptor plate is pretty much
what you are stuck with.
Well ... I can think of one way. Machine matching T-slots in
the back of the adaptor plate. Then make a special T-nut to go in
there. It has a hole drilled parallel to the T-slot, into which you put
a rod which can be turned from the outside. Offset the rod and turn an
eccentric in it about as wide as the T-nut's bolt size, and put a
headless bolt in there which is cross-bored for the rod with the
eccentric. Turning the rod will draw the bolt towards the special
T-nut, and if you have a normal T-nut threaded onto it, they will get
closer together. (Perhaps make the bolt and the T-nut with particularly
fine threads, so you can adjust the spacing to work.
Make as many of these as your table has T-slots. Put the chuck
onto the rotary table (ideally with something to assure that it is
concentric every time), loosen the eccentrics and slide in the pair of
T-nuts into the T-slot in the rotary table and the one in the adaptor
plate. When all four (or three) of them are installed, reach in with a
wrench and turn each eccentric to lock it in place. Make sure that
there is some way to grip the assembly to pull it out when you are done.
(You could have the eccentric rods long enough to reach out of the
T-slot where you can grip it, if this won't get in the way of various
operations with the rotary table.)
If you are going to pull the paired T-nuts out by the eccentric
rod, turn a groove in a non-eccentric part, and put in a dog-point set
screw so you can pull on the eccentric rod without pulling it out. :-)
I hope that this helps,
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