On Sun, 12 Dec 2010 10:06:02 -0500, "Wild_Bill"
wrote:

This type of chuck isn't ideally suited for most large lathes, but it's
sufficiently adequate for use on a generic 9x20 model.
I don't know if the chuck is a good choice for thin rings, though, as jaw
pressure could easily distort the ring (much like thin tubing).. the flat
faceplate may be a better choice (with some fittings added).

Agreed.


I've used the same type 4-jaw on my own 9x20, and it isn't substantially any
more difficult to use than a heavy duty 4-jaw chuck.
Like many pieces of tooling from China/elsewhere, it was kinda rough as
supplied. After deburring all the parts and edges, and smoothing the sliding
surfaces, I replaced the soft flat washers under the nuts with hardened,
ground flat washers. That may not seem like a major issue, but those
original soft washers don't give a good feel of when a fastener is tight.

Backing off the jaw nuts just enough to allow for minor adjustments may be
the key to ease of use with these chucks.

Hardened/ground washers offer a significant improvement in feedback of
tight/just-snug within a short wrench swing.. I generally install them where
repeated use is common.
When a fastener has 90+ degrees of swing from tight-to-snug (backing off),
something is wrong.. the bolt isn't stretching, and the cast iron isn't
compressing, so it's the soft flat washer.
Another cause of wrench "overswing" could be that the threaded hole in the
nut isn't perpendicular with the flat sides, which is a fairly frequent
occurrence with Chinese hardware.

Sounds like a cheaper solution to try before getting a whole new
chuck.

A HD 4-jaw will have other issues, such as the correct spindle thread and
matching register seat for the 9x20 models with metric thread spindles.
Another issue with a HD 4-jaw is the workpieces will always be supported
further away from the spindle nose bearing, which will most likely result in
more tool chatter when not using tailstock center support.

I had no problem with the spindle thread, unlike the face plate that
came with the 9x20. I could not get it on the spindle. The vendor sent
a replacement which they swore fitted OK on one of their spindles.
Same problem. I had to re-thread both plates and it was not a subtle
process of a few thou. I had to take a fair bit off.

Michael Koblic,
Campbell River, BC