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.
None of those things is true of a 4-jaw *self-centering* chuck, which is what the guy was talking about.
Ah! 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 may not.
Harold
Sounds like a strong gripper - just a notch above a 3. Likely used on square stock that went to rounds. (Typical in wood).
Is is a wood chuck ? - might not be as strong as a steel use chuck.
Martin
How much wood would a wood chuck chuck?
-- Bob (Chief Pilot, White Knuckle Airways)
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.
GWE
stock(good
contact,
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 a shredder.
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 opposing jaws....
Yours,
Doug Goncz Replikon Research 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.
Koz
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.
Harold
That makes a useful tool from one that is basically useless.
Harold
Some of the largest were 24' columns. Hand tapered. That was some chunk of wood. Martin
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