Thanks for the insights. I am a hobbyist so speed of loading is not an issue. I only use collets for stock <1" for better concentricity and grip but I use 3 jaw for larger. THanks for the heads up about short pieces.
LOL! I wouldn't use - nor even OWN - a 3-J scroll at
gunpoint!.
It ain't JUST the concentrickery, TIR, or lack-thereof. There
are a few "Old Skewl" tricks as far as shimming, pulling one jaw, pulling TWO jaws.. use of pie or soft jaws, dowel pins, fixtures, etc, but still..
.. mostly they do only round shapes and multiple of 3-sides - hex the obvious one.
My "real reason"?
3-J scroll only have
half the GRIP of a 4-J independent!
Back to "crawlits"..
I
have 5C.. In 64'ths, even ...but don't LIKE them very much, prefer to use my 4-way-split 2J (Sjogren, and Hardinge "loop" lever-operated nose-closer.)
But
yah pretty well HAVE to have 5C.. because ..it is the
least cost and
fastest to get goods as can cover:
- Hex, Octagonal, square, oblong rectangular.. custom EDM-sunk or milled odd shapes.. PLUS lower-cost steel, brass, and nylon soft or "emergency" collets. Of which one keeps a few "virgin" ones in the drawer. And saves ones already bored for a specific "one time" tasking. Because they can be modified AGAIN. With a "step" as well as any larger diameter. No collapse-control pins? Just use three slivers of shim stock.
- INTERNAL expanding 5C are less costly and more easily sourced than 2J, etc.
- Step and pot chucks, as SMT mentioned, can also be sourced, new or used, at more reasonable cost than alt-spurnitives.
"And then.." one has 5C spin indexers, square, hex and round 5C "collet blocks" for use as workholding not ONLY on the lathe. Bench. Mill. Rotab. Indexer. DH. Grinder... 'etc'
I'm jealous of not "wasting" the skinny bore on my 10EE's so I have
no "drawtube" collet systems for the lathes at all.
- Both 5C are nose-mount, key operated. No drawtube.
- The 5C step/pot closer is the same, pin-spanner operated on a Hardinge threaded "false nose". Drawtube or "similar".. only "sometimes".
- The 2J are Sjogren or Hardinge "loop" closer. No drawbar (or 2-piece tube).
- Rubberflex 9XX nose mounts, operate off a rimmed wheel. No drawtube.
- Burnerd Multisize is a nose mount, "loop" closer operated. No drawtube.
- the ER, TG, a "dead length" collet system or two, (for the mill) are also spanner operated at the nose. Off a B&S #9 adapter on the mill which DOES have a drawbar. Several drawbars, actually, because there are two mills and a DH/indexer that use #9 B&S here, two more spindles in 40-taper, two lengths. More than one thread. Life finds ways to stay interesting one way or another..
The ONLY "drawbar" collets I have
are native 40-taper, native B&S #9 for the mills.... and dividing head, 5C indexer, rotab, etc.
And not the lathe(s).
Plan your spend:
ER can get you operational as low-spend #1.
First thing I acquired besides the several sizes of 4-J chuck and faceplates for the first 10EE, actually. It was blessed with 2-J chuck, 6-J chuck, magnetic chuck,
later.
Even so, 5C is a "good idea" for reasonable "spend #2". It gets you
value-for-money FLEXIBILITY, mostly.
Damned-near ANY other "spring" collet system costs more than 5C. Usually double or more than double.
....Even if you prefer 2J, 3J, Rubberflex, Multisize if/as/when.....
later.