Wood Balls, Mallet & Overlapping Circles - #2 Turning & Finishing the Balls

With the jigs done I removed them from the lathe took off the scroll chuck, put the drive center back in, changed out the live center to a different style and mounted one of the test ball blanks between the drive and live centers.  Next is to mark a line centered on the cylinder and then lines to the left and right of that equal to the radius of the cylinder.  What you end up with is the outside edges of the ball centered on the cylinder.  Take a look at the photo below, it probably makes more sense than my description.

Now the actual turning of the ball can begin.  First step is to cut down the area beyond the ball diameter on both ends.  That completed I can start to cut an arc that sort of matches the radius of the ball to be.

To help me out in getting the right shape I cut a paper template with a radius about 1/16” larger than the ball’s finished diameter.  More turning gets me closer to the shape I am looking after.  As I get closer to the final size I am also turning the stems on either side down.

Here is the end of the first part of the turning.  The ball is pretty close albeit oversized by a bit.  Note how small the stems are now.  They are cut off fairly close to the ball with a fine-toothed saw.  I use a thin Japanese pull saw.

Now is when the jigs I made in Post #1 come into play.  Think of a line through the stems on the ball as the X axis.  When I put the ball in the jigs I set it so that axis is 90 degrees to a line that runs between the head and tail stock.  You can see the cutoff end of the stem centered between the jigs.  When I start turning they will get removed. 

As I turn I will be looking for those shadowy areas along the edge of the ball indicating the piece is out of round.  It is similar to what I was talking about when I was rounding the ball blanks to a cylinder in Post #1.  There is not a lot of material to be removed so a light touch and sharp tools are needed.  When done with this step the stems are gone and the ball is closer to being a sphere.   It is critical at this step not to remove the existing pencil center line reference.  If that is done then the overall size of the ball is reduced in this axis and you will have to go back to the original axis setup and bring the overall diameter down.  Not shown here is the marking of the center line with this setup.  I did it after the photo was taken.  It will align with the balls glue joint.

Next is to rotate the ball once again 90 degrees to it’s Z axis and go through the same process of gently removing material until the shadowy areas are gone or nearly so but not removing the two pencil center lines.  It may be necessary to go back through all three clamping setups with the jigs to touch up the X, Y and Z axis’s to get a round ball.  Just remember you are not making ball bearings so they don’t have to be round within a gnat’s whisker.  When done turning its time to start sanding.  Work your way through the grits starting with an appropriately coarse grit sanding on one axis then rotating the ball then sanding on another axis until you have gone through all three of the axis’s.  Move to a finer grit and go through the process of sanding, rotating the ball, sanding, rotating, etc. until you end with a grit fine enough to remove visible scratches.  

The sanding can be done by hand or using some power assistance.  I have done it both ways.  Here I am using a drill with an attachment that has a soft pad on the end and uses a hook & loop sandpaper mounting system to hold the sandpaper in place.

When done sanding the last step is finishing.  For these balls I used a friction applied wax finish. 

 

The application method is to get the ball spinning and then rub the wax stick against it using the friction to melt some wax onto the ball.  I then pressed a folded piece of an old clean white cotton tee shirt against the ball with the lathe spinning at about 1,200 rpm’s.  The friction between the cloth and the piece melts the wax into the ball giving a nice smooth finish.  I will turn the cloth to a fresh surface and buff the ball to a final polish.  Once again just like the turning and sanding the ball will need to be rotated so the wax can be applied on each of the X, Y and Z axis to give an even finish.  This is the ball with the completed wax finish and the cloth I used to buff it out.

Here is the ball finished and out of the jigs.  It looks and feels perfectly round but to tell the truth if you were to put a micrometer on it there are very subtle variations in the diameter.  However, like I said before these are not precision ball bearings!

Once I finished the first couple of test ball I decided to make some more using different woods.  The next one made from mahogany was going to be a lot larger than the test pieces.  However, as I started turning I uncovered a big crack hidden inside.  By the time I got rid of it the big ball had turned into two smaller ones.

Anyway, I ended up turning 7 balls of different sizes and materials.  I made them out of construction lumber (the test pieces) mahogany, oak, cherry and hard maple. 

One additional thing that I did learn was when doing the finishing is it helps to add a bit of paper towel between the ball and the jig.  Doing that does a couple of things.  First, it provides a little bit a friction between the ball and the jig.  In more than one instance while I was doing the buffing and was pressing the cloth against the ball to generate some heat to melt the wax the friction between the ball and the cloth exceeded that between the ball and the jig.  The result was the ball stopped, the jig did not and the I ended up with a ring where the jig burnished the ball.  In one case it was bad enough I had to go back and re-sand the ball to get rid of it.  Second, it provides a little bit of cushion between the ball and the jig.  That’s not really a problem with hard woods but with the softer ones the jig would actually dent the balls if I tightened the tailstock too much when trying to keep the ball from stopping while doing the buffing.

Next Up – Starting on the Mallet