My dad is getting up in the years and is cleaning out some of his
unused/nolonger used tools. He gave me a 8" 4 jaw chuck that was made in
Germany. It has never been used and will need a backing plate. It is a 4 jaw
with self centering jaws, I have not come across any of these in my travels.
It must work well with square stock and would work just as good as a 3 jaw
on round stock, any other things I am mising?
Actually, if you use a good dial indicator with a four jaw chuck, you can
turn perfectly round stock. (zero runout)
If you do the same thing, you can turn a round post on square stock(good for
cam lobes), or elliptical lobes for whatever....
nice thing to have for extra precison... good luck.
But not with this one! This is a universal 4 jaw, not an independent 4 jaw.
Very nice for gripping square objects, but inclined to grip only with three
jaws, or, really, two. The moment you move away from 3 point contact,
things get more complicated where chucks are concerned, unless they are
independent. It likely would not perform as well as a three jaw chuck with
round stock due to the tightest jaws gripping, with the set at 90 degrees
gripping, or not. In a perfect world they make sense. In practice, they
I have a 4-jaw scrolling lathe chuck. Each jaw is independantly adjustable
just like a normal 4J but there is also a scroll so once you get it dialed
in you can back it out and go back in. Mine is made by Rohm or someone and
cost nearly $1400 new which is a lot for a 6" chuck. No way is this one
made for wood. I think you can still see these in the MSC catalog. Wear
diapers -- the prices are *astronomical*. I got mine on ebay before it got
"discovered" and the prices skyrocketed.
I find a wrapping of paper makes such a chuck grip more reliably.
I refinished a Harbor Freight cheapie four inch four jaw universal
chuck with Clover Compound. It took hours. I removed the scroll and
pushed each jaw through each slot in both directions, both
orientations, using a 1/2 ton arbor press until things started evening
up, then I got the grit out with a toothbrush. Yes, it was so tight it
needed the arbor press; finger pressure wouldn't do it. The work was
intensely boring: press, reverse, press, repeat, count jaws, move to
other slot, count jaws, etc....
Sad, though, you can never get all the grit out. It sure works smoothly
now, but how long will it last? It was for circular milling and hole
pattern drilling on a 20 mm dowel pin, and could use a brass bush for
the dowel pin.
I still have this chuck but we are in extreme cluter mode, not quite a
hoarding situation, and I wonder if I will ever use it. We (Teri and I)
may choose to pay somebody to help us sort out this crunch. We do have
The paper adds elasticity to the grip and can completely remove the
"overcontstrained" condition. Three point contact and all that
kinematic design stuff. I love four jaw self-centering chucks. They
work really well with wood and plastic; no shim is needed because the
work is so elastic.
A modification to a standard four jaw independent chuck is to procure
hex stock or a Balldriver that fits the screws, then drill the interior
to allow this long, skinny tool to adjust two jaws at once. With a
total redesign, you'd have a self-centering independent chuck. With the
mod, you have a quick-centering four jaw chuck. Wups. There goes
another patentable invention. Left and right threaded screws on
Seven Corners, VA 22044-0394
4 jaw scroll can also be good if you have to bore a sprocket or gear
that has a tooth count divisible by 4 and have to grab the tooth
gullets. Not the kind of thing you may do every day but when you need
it, it can save one hell of a lot of fiddling.
This is an excellent example of where soft jaws shine. Concentricity can
be very reliably established, assuming the gear or sprocket was established
concentric with the major diameter originally. The added benefit of soft
jaws is the ability to locate your parts time and again at a perfect right
angle, assuming you make the jaws properly.