Here is what I’m trying to make.
Essential to this type of work is a chuck to hold the blank ball for drilling the 22 holes at different locations and to hold it in various positions for the turning of the 4 internal balls.
BUILDING THE CHUCK BODY
The outside dimensions of the chuck are flexible as long as there is enough ‘meat’ around it to hold a faceplate or to accommodate whatever other way you might want to hold the chuck onto the lathe with, and also for the screws which hold the collar in place to lock the ball securely into the chuck.
This blog will be somewhat tutorial because I have made a better chuck than the one recommended in the book ‘Woodturning Wizadry’, and this might help out someone else doing this project.
This is my third chuck. The first one sucked, the 2nd one was a good concept with a flaw, and the third one is in my opinion bomb proof. That remains to be seen, as I haven’t actually used it yet!
So let’s get started!
1. Glue up
I started out face gluing a couple of 4-1/2” squares of 3/4” wood together as shown above. I used white oak because I wanted a heavy wood to run more vibration free on the lathe.
2. Drilling holes for the 1/4”(M6) collar screws
The next step was to add one more square of the oak and the 1/2” mdf for the collar, both fastened using double sided tape to prepare them for drilling the four collar screw holes, which, as you can see have already been done.
3.Installing threaded inserts for the collar screws
After drilling deep enough to insure the proper depth to install screw-in threaded inserts, I removed third layer and drilled the holes out big enough to accept the threaded inserts. They are shown being screwed in above. I could have glued all 3 oak squares at one time and screwed in the inserts from the top, but I didn’t want the screwdriver slots on the top, so I inserted them from the bottom, which will then be glued onto the other two boards.
4. Final glue-up
After gluing on the 3rd board with the inserts and with the mdf collar still attached, I added a 4th board to protect the MDF while in the glue clamps as shown.
5. Getting the chuck body ready for turning
A faceplate has been mounted onto the chuck body and cut round in the bandsaw.
Before mounting the chuck onto the lathe I wanted to makes sure my headstock and tailstock were properly aligned.
The chuck body is now mounted on the lathe and the tailstock brought up to mark the center for hollowing out purposes. The lathe was aligned to make sure the center marking would be correct.
6.Turning the chuck body
The outside is first turned smooth and then a ball shape is turned into the center of the chuck using a half ball template. The diameter is 62mm or about 2-7/16” in diameter.
Here it is the finished hole in the completed chuck body.
MAKING THE CHUCK COLLAR
1. Marking out the collar
Here you see the marked out collar. There is a line 1/2” from the center line bisecting the circle. That is the same thickness as the collar and it’s length denotes the diameter of the hole to turned in the center on the top of the collar. The bottom of the collar hole will be turned to the same diameter as the hole in the chuck body. In this case the top hole diameter will be our first target. Please note that the screw holes have been countersunk.
2 Turning the collar
The collar is being attached to the chuck body with the four screws which are held by the threaded inserts.
The outside edge of the collar is turned to the outside chuck body diameter, and the center hole cut out. The next step is to enlarge the internal opening of the collar hole to the same diameter as the chuck body (2-7/16”. This is a curved cut that follows the shape of the ball 1/2” out from the front of the chuck body.
Here is the completed chuck with the tailstock center pushing the ball in tight before screwing the collar. the 2nd photo shows the chuck holding a ball ready for work!
These are the three chucks named From left to right ‘Chuck’, ‘Chucky’ and finally ‘Chuckles’. I hope this blog wasn’t too boring. I just had to get it out of my system, lol. Thanks for reading.
The next blog with be about the special tool rest needed for the special turning tools. The following links cover all the blogs in the series to date.
-- Mike, an American living in Norway.