attaching 3 jaw chuck to rotary table

[blockmanjohn]

Hi all,
I have a vertex 8" rotary table with 4 t-slots and an mt3 taper in the center. I would like to attach my 5" 3 jaw chuck to the table. The chuck has a backplate with a 1 1/2x8 thread on it.

I was thinking of making an mt3 spindle with a 1 1/2 8 male thread on it, but this still won't secure the chuck to the table very well. Maybe a new backplate with an mt3 spigot on it and secure the chuck with clamps. Lastly I was thinking of a backplate that had slots for t -nuts which would slide into the table slots. I guess these nuts would have to be made very carefully.

Anyway, just wondering if any one has done this all ready, or can point me in the right direction? Thanks in advance, John.

 

[petertha]

You can get an MT3-1.5x18 adapter like this...
http://www.shars.com/products/toolh...er-2-shank-1-1-2-18-threads-for-boring-head-1

...but you may want to check the RT table hole diameter relative to the arbor. What I'm getting at is the arbor/RT taper may fit but the arbor may be sticking up somewhat & the chuck sitting on top of that in a not-so-great way support wise. Also this may seem centered but all depends on accuracy you need to hold. A 0.003" TIR chuck runout will never be concentric to the RT rotation axis. So a dedicated plate like my pics would give you control or else maybe consider a 4-jaw.

If your the 1.5x18 adapter plate can be removed relatively painlessly revealing a plain back chuck, you can make a dedicated plate like my pics. This has more versatility, rotary table, mill table, or directly in a mill vise already mounted. This kind of flush plate is a much more stable platform for milling & drilling.

But if its an integrated chuck or the chuck fits very snug on the adapter plate register shoulder & you depend on that for accuracy, then those disadvantages will outweigh.

You also should measure how the 'wedding cake stack' compares to your mill headroom because RT + adapter + chuck + work piece can gobble up vertical room.

 

[Wizard69]

You need a new backplate and that needs to be bolted to the rotary tables T slots. You don't want "precision in your nuts and bolts, rather you will need to dial in the chuck for each use. This is one reason 4 jaw chucks are often used on rotary table as you can dial in runout with respect to the table relatively easily.