> Firstly - thanks to all those who took the time to reply to my
> previous enquiry (Bridgeport milling questions).
> I also purchased an old Colchester Student 6 and this was supplied
> with a 3 jaw chuck, a 4 jaw chuck and these (which I'd never seen
> There are 12 sprung collets, numbered "EC2....EC13", all seem in good
> condition - the jaws move freely and spring back with good force.
Nice collet chuck and collets. Looking at the threads on the
back of the chuck, I presume that your lathe's spindle is a L-00 or
> After a little digging, it appears they're quite highly regarded for
> precision work although I'd welcome your comments.
> I've only ever used a standard 3 jaw chuck before and this has been
> perfectly adequate for my hobbyist needs. I can't forsee any
> "precision" work in my future and wondered if I'd be better selling
> these and using the money for other tooling.
> What do you think?
Have you ever tried mounting in a chuck something which was
already to final diameter in your chuck and turning an extra feature
concentric with the existing OD?
3-jaw chucks are known for having noticeable runout when you try
to do something like that. If you measure a runout of 0.003" or less on
a 3-jaw chuck, you have an exceptionally good one.
4-jaw can be adjusted to tune out the runout -- but it takes
In particular, the collet chuck is useful when making multiple
parts from bar stock which will fit through the spindle.
My 12x24" Clausing has a lever closing drawbar for 5C collets,
and I tend to use them whenever possible, only shifting to a chuck for
larger workpieces (the 5C stops at 1-1/8" diameter for short workpieces,
and 1" diameter for through feed stock), or when something is of
irregular shape or needs to be cut to make an eccentric, both of which
call for the 4-jaw chuck.
I would say keep them. (Or sell them to me, if the spindle nose
truly is L-00. :-) But you will regret selling them.
What is the size of the EC-13? Is that in mm, or something
else. They look larger than my 5C collets. If the count is in 1/8"
steps, then you can handle up to 1-5/8" diameter. Maybe even larger.
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