Jaw alignment

[Chris152]

The jaws on this old chuck don't seem to line up nicely with the chuck. All looks fine otherwise with both, except that the band pulling the jaws together was broken so I inserted a rubber band that seems to do the job.

It seems to have a good grip on the mortice. Does it look ok to use, though? I want to use this one so I can have a smaller mortice than I can get with the other chucks i have (it'll fit a 2" forstner mortice so quick to mount). The alternative looks expensive.

Thanks, Chris
ps I've taken the twist out of the band and the jaws are still the same.

 

[CHJ]

Nothing wrong with the jaws, they are not set to the correct PCD, (a true circle) and are probably tipping out of alignment.
Set to correct diameter I would expect to see 2 to 3 mm gap between the segments.


As an aside, Dovetail Jaws do not give their best holding characteristics in a plain forcestner bit socket, should really have a matching dovetail socket rather than just relying on jaws compressing an impression in the bore.

 

[Chris152]

Thanks Chas. Reassured by what you'd written I had a go and they worked perfectly. And what you said about the dovetail combined with a £25 cost for a 2" forstner bit convinced me that attaching to a faceplate and turning the 2" mortices and base/ underside of a few bowls, then swapping the chuck to the one pictured to do the insides of the bowls was the way to go.

Cheers, C.