Clamping a 4jaw Chuck on a Rotary Table

[Downwindtracker2]

After trying to make a hex on a round using my milling machine vise's base degree markings, I ordered a 6" 4jaw chuck for my 8" rotary table. Maybe next time there will be less filing. chuckle . When I bought my mill/drill it came with a 8" 4jaw on a piece of aluminum plate .( if I can find the plate) Will that be accurate enough ? I'll use the 8" on my lathe .

 

[whydontu]

As long as the plate is flat, even a wildly off-centre 4-jaw chuck will work. Align the rotary table centre to the mill spindle, bolt on the chuck as close as possible, then align the workpiece in the chuck using the jaws to adjust concentricity.

 

[PeterT]

Here are some ideas. I made a round adapter plate for the RT which accommodates both a 3J & 4J chuck (different bolt patterns but same back recess). The hold-downs must match your RT slots of course. Also made a rectangular chuck plate which can be mounted directly on mill table or held in mill vise (its only a 5" chuck). If you machine the plates yourself, you have some confidence of their accuracy. The thing to consider as you use larger chucks on a RT is the stack-up starts to grow. So depending on the mill, cutting tools & part held, you might start to run tight on vertical room. So do some measurements beforehand. Reversible jaw type chucks can help a lot with setups.

 

[1018Machine]

This is what I did using a 3 jaw chuck, it's still able to be located into zero much like a 4 jaw only the whole apparatus moves. I also have a four jaw chuck mounted to my 6" rotab like one in PeterT's post.

 

[Susquatch]

Lots of other ways to do this too.

Eg - 5C indexer, 6 sided collet block, two nuts locked together, 120 degree block, Rose Fixture, etc.

And of course, a great thread on the general subject with lots of ideas here:

Thread 'Rose Index' https://canadianhobbymetalworkers.com/threads/rose-index.6063/