Chuck vs. Collet. Turning down & re-threading Damper rods

3 jaw self-centring chucks are a quick & convenient way of holding work in a lathe, but with standard hardened jaws the work doesn't run dead true & wear over time generally makes run-out worse. A few thousandths of an inch run-out is not always a problem though, & on this job I thought we might get away with it. However, the repeatability of holding the work was also not too good so I decided it would be better to take the 3 jaw chuck off the lathe & fit a collet chuck instead. Much less run-out & much better repeatability. I should have fitted the collet chuck in the first place. If in doubt, use a collet! Lathe used here is a Colchester Triumph 2000 3 jaw chuck is a standard Burnerd 10" self centring (scroll) type. Collet chuck is a 2" capacity lever operated Burnerd Multisize.