Friday, October 07, 2011

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
  1. its size which is generally limited to one half inch although slightly smaller or larger ones are available for some lathes
  2. its having three jaws which make it awkward to hold onto a square piece of wood
  3. 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.


Hockeypuck said...

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!!

Darrell Feltmate said...

my pleasure. Glad it worked so well. Mine suits me well.