Here are some on-line resources for turning spheres:
The jig I was using is a Chef Ware Kits EZ-Jig. Click here for the link.
For the “octagon” method of roughing out a sphere, this blog post by Keith Larrett, gives the method with slightly higher precision than I did And, with pictures.
Jerry Takes came up afterward and briefly explained an alternative method for turning a sphere, using a bright light and a pencil drawing of a circle. Click here for one explanation of this method. There are more links at the bottom of the linked article.
Here is wordy description of the process I gave the other night for roughing out the sphere blank:
- turn your blank to the desired diameter of the sphere, or perhaps a little over sized.
- find and mark the “ends” of the sphere on the blank (transfer the diameter of the blank to the outside of the blank)
- find and mark the center of the sphere on the blank.
- from the center, measure and mark .2 of the diameter toward each end of the blank
- at end end of the blank, use a parting tool to make a tenon .4 the diameter of the blank
- use a spindle gouge to make a 45 degree cut from the lines established in step 4 to the tenon established in step 5, both ends of the blank
- You should now have roughly a blank with the .4 measurement (.2 plus .2) across the top, equal to the .4 tenons and the 45 degree bevels
- use a spindle gouge to round off the corners of the “octagon” and you have a fairly good representation of a sphere (some people actually add a step here to make a “16-sided” blank) before they do the corner rounding
Comment: if the first one doesn’t work out, use what you learned and try again.
Finally, thanks for all the nice comments about the demo the other night.