Rotary Table Chuck Adapter

I would be curious to hear your solution. All the ones I have seen in person are a smaller chuck than the table. The one I made for my own use is a 3" chuck on a 4" table.

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. Eric

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 machining it!

Lloyd

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 .

Perhaps you could disassemble the rotary table and drill it for bolts from underneath. jsw

I didn't try to get proportions right, but you should be able to get some variation of this to work:

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 desirable).

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, DoN.

That's the simplest solution so far. No drilling the chuck or complicated wedges/cams to machine.