Mounting Wood On The Wood Lathe: Do Not Forget The Jacob's Chuck
One of the best and worst things to
happen to modern woodturning is the invention of the four jaw chuck
for holding wood. While it is a great addition to the woodturner's
asenal, it is also an expensive tool and many beginners find that it
costs more than their wood lathe. Also, like many tools a cheaper
version is aggravating and in some cases simply dangerous to use. One
thing to remember is woodturning has been around for thousands of
years and there are many ways to mount the wood without the newest
fashions. The Jacob's chuck is a great tool for all turners.
A Jacob's chuck is designed for
holding drill bits. It is the chuck on the end of the drill press or
the electric hand drill. As such it is often used held in the tail
stock of the lathe to hold a drill bit for putting a hole in a piece
of wood in the head stock or vice versa. However, it may also be used
to hold a piece of wood for turning.
The difficulties in using a Jacob's
chuck for holding wood are
- its size which is generally limited to one half inch although slightly smaller or larger ones are available for some lathes
- its having three jaws which make it awkward to hold onto a square piece of wood
- it is made for holding metal and may well crush the wood in its jaws
These limitations are easily dealt
with.
The time to use a Jacob's chuck is
generally to turn a spindle that needs to be held on one end only.
This means that the stronger grain orientation of long grain is being
used as opposed to face grain. In such circumstances a piece of one
half inch wood such as maple is easily strong enough to support a
three inch spindle of reasonable length. It remains to mount the
spindle first between centers and turn it round, allowing for a short
length at one end to be turned down to one half inch so as to fit in
the chuck. Now it can be remounted in the chuck, trued up and finish
turned.
Note that this also removes the second
difficulty of trying to fit a square piece of wood into a three jaw
structure. The tenon to fit the chuck is now round. It also deals
with the third problem of crushing the wood. This would serve to mar
the wood and also to move the piece off center for turning. A truing
cut will put it back on center and the tenon is considered waste wood
and removed from the finished piece.
The old and established technology of
the Jacob's chuck is not as versatile as the newer four jaw chuck but
it is reliable at a much lower cost and opens new avenues of wood
turning to the beginner without a lot of expenditure. Besides which,
a Jacob's chuck is a welcome addition to every turner's arsenal.
2 comments:
I have recently made a "cole jaw" system for my four jaw chuck that you posted plans for on your website and they turned out great , no pun inteded. Instead of turning my own pegs I used well nuts for the holding system. Thanks so much for the idea and easy to use layout of your plan. Very exited to use these and will add a whole new beauty to the underside of my bowls rather than sanding off the tenon on a mounted belt sander. Thanks a bunch!!
my pleasure. Glad it worked so well. Mine suits me well.
Post a Comment