Spheres with tangents and templates

[John Kelsey]

For this week's Lancaster Woodturners coffee hour Angelo demonstrated sphere turning by the traditional method of tangents and templates, here's the video it's 8 mins:

View: https://youtu.be/wtJ3ekHfo3E


Woodturners Coffee Hour is open and free on Zoom every Thursday morning from 10 - 11 EST, message me if you'd like to visit.

 

[Dennis J Gooding]

An interesting video, but he does not explain how he comes by the hexagon pattern to do the measuring. One method is to measure or choose the diameter of the sphere and use a calculator to compute the facets of the hexagon. You may be interested in an alternative method of determining the measurements needed for spheres, spheroids and ovoids with no calculation required. I posted three articles in the Tutorial and Tips Forum on this subject. The are:

Simple Aid for Turning Spheres without a Jig
Simple Aid for Turning Spheres and Spheroids Without a Jig
Simple Aid for Turning Ovoids

 

[John Kelsey]

Yah the dudes on the coffee hour shared several different ways to construct the octagon in the size you need.

 

[hockenbery]

Yah the dudes on the coffee hour shared several different ways to construct the octagon in the size you need.

Angelos&myrons method is a good one and is well suited to get a sphere of an exact size.
And a template should be constructed as accurately as possible.

Your math examples are good.
Here is another explanation


the method I use is to turn between centers and rotate the ball. I cut my blanks DxDxD+1/2
I get a sphere a little less than diameter D, the 1/2 added to the length takes the center points.

after using .41 for years it occurred to me that I was an applied mathematician whose job is getting the wrong answers fast but knowing how wrong they are.

so .4 works great for balls smaller than 6”.

my method

Also I find a using a ring check the sphere much better than a template.

 

[Charles Chaloupka]

For this week's Lancaster Woodturners coffee hour Angelo demonstrated sphere turning by the traditional method of tangents and templates, here's the video it's 8 mins:

View: https://youtu.be/wtJ3ekHfo3E


Woodturners Coffee Hour is open and free on Zoom every Thursday morning from 10 - 11 EST, message me if you'd like to visit.

John can you send me info to join Thursday coffee hour. Thanks Chuck