To turn the ball you will need a piece of timber the size of the required ball plus 2mm X diameter plus 20 – 30mm & a template to the required radius of the ball.
Step 1: Mount the Timber
Step 2: Measure and Mark
Step 3: Repeat
Step 4: Cup Chucks
Step 5: Remount the Ball
Step 6: The Ghost Line
Step 7: Centre Point
Now with a 3mm parting tool equally straddling the line and always, pointing to the centre of the ball we can turn the fist groove to a depth of approximately 4mm, then with a small ruler measure a gap of 3mm before then again cutting a groove to the same depth & in the same way. Repeat the process around the tailstock end of the ball, it will be necessary to remove the tool rest to turn the last grooves.
Next turn the ball round and using the grooves to centre the ball remount it to the scrap timber, you can now repeat the process to turn the grooves to the second half of the ball
Step 8: Cut in Half
Step 9: Grooves
Now again with the tool at 90 degrees to the wall & starting about 5mm in from the top edge, we can cut our 1st groove to a depth of 4mm but take it easy as you reach your final depth, if your turning has been accurate up to now and you don’t rush in to deep you will feel a light skip in the chisel and you may see the grove become lighter, this is the point where it pierces the outer groves, stop and check this from now on take very light cuts & check regularly it will break if you are to harsh with your tooling. Repeat the process leaving 3mm sections between grooves.
Step 10: Curved Lattice?
Step 11: Conclusion
Also Ashley Iles sell a 3mm bead cutting tool which can be used to round over the beads as in the pictures, this is a tool well worth adding to your tool set.
Finally the best parting tool for the beads I have found is the one Robert Sorby make the handle length is small enough to work in tight spaces without compromising on the length of the steel, sadly mine was lost in the time I was away from the lathe but Crown do a good alternative slightly to long to get into small spaces but works, don’t opt for too small a tool you need a tool you can get a firm grip on to work well.
I have tried to break this down to 14 steps, it is not always easy to get the point across in a short text so if you need any further help just ask and I will get back as quick as possible
Lastly if you want a more in depth explanation to follow there was an article written in Practical Woodworking, June 96, I don’t know if it is still available in back orders or maybe someone might have a copy.
Good luck and enjoy.