Ran out of screws?

We tried fitting the independent 4-jaw that came with my son's lathe today.

The fact we hadn't discovered this until now shows that my doubts about the usefulness of his self-centring 4-jaw were nearly as mistaken as the bill of materials. Luckily I had some suitable hex head screws, so only a few minutes lost.

Brian

Perhaps they forgot to counterbore the backplate.

Face enough off the capscrews, to dispense with the spacers, and allow the backplate to contact the Mandrel flange, and better engage the register?

After all, they are only going to removed / replaced on the odd occasion when the chuck is stripped for cleaning.

Howard

The spacers pass right through the mandrel with the nuts left in place Howard, and a rotating plate with three keyhole slots is used to retain the chuck. Without those caphead screws getting in the way the backplate is hard against the mandrel with a register protruding into the central hole. It is much more convenient than the more usual Chinese flange and nuts, taking well under a minute to swap chucks.

The 3-jaw uses hex head screws that have plenty of room in the recesses, and I used the same both on the self-centering chuck (with a modified Sieg SC6 backplate), and to replace these cap heads. As you said, they aren't going to be removed very often, and there is plenty of room to use a 13mm open end spanner.

Brian