How to adapt a M2/M3 taper Jacobs chuck to an R8 fixture?

Janderso

Janderso

Jeff Anderson
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Hi guys,
I picked up several very good American made Jacobs chucks yesterday and one German made keyless chuck. They are all M2 or M3 taper. My problem is, how can I use them in my 3/4 jaw lathe chucks and or my Bridgeport R8? Lathe tail stock is M3 on the old South Bend.
Thanks.
Jeff
 
On the Bridgeport you can get an adapter from R8 to either MT2 or MT3. You will consume some nose-to-table height and may add a bit of runout.

An example of the R8 - MT2 at Shars, they also have the R8 - MT3
R8 - MT2 at Shars

To hold an MT2 or MT3 in a chuck you need a sleeve which is parallel on the outside and the MT on the inside. Not as common but available. Some places call this a sleeve some a socket. At MSC they call it a socket.

MT3 socket at MSC
 
Jeff, most chucks will have a Jacobs taper in the back of the chuck. You can remove the current MT and use an R8 to JT arbor. It will be more accurate than interfacing with yet another adapter and probably have less potential for slipping. Unless I am misunderstanding something here.
 
As they should be on a jt taper. But if they are in fact integrated, just turn the mores taper down to a straight shank and put them in a collet.
 
Whoa, that's a good idea. I assume a carbide bit to cut the taper? How do I take/remove it if they do seperate? I have one that has a Jacob's Chuck with a "Japan" tapered shaft and tang. I know that is two pieces, just have no idea how to unscrew? the pieces.
Thank you very much
 
Janderso said:
Whoa, that's a good idea. I assume a carbide bit to cut the taper? How do I take/remove it if they do seperate? I have one that has a Jacob's Chuck with a "Japan" tapered shaft and tang. I know that is two pieces, just have no idea how to unscrew? the pieces.
Thank you very much
Click to expand...

The taper may or may not be hardened. The taper does not unscrew. You need to purchase a pair of wedge of the right size for your chuck. An example page of Jacobs wedges at MSC. May be less expensive at other locations.

Inserted from opposite sides in the groove in the adapter.

Jacbos taper wedges at MSC
 
Dave,
I place the wedges opposite in the groove and place in a vice and carefully press the chuck from the shaft?
 
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