Calculation of Ring Sizes for Segmented Spheres--A Correction

[Dennis J Gooding]

Despite numerous proof reads before posting this thread in the Tutorials and Tips Forum, I managed to define a parameter incorrectly. The parameter θ was incorrectly defined as θ =180/N, whereas it should have been defined as θ = 360/N. I have since corrected the error, but just in case someone is already trying to use the old result, beware. SFTI

 

[Dennis J Gooding]

Additional Useful Parameter

I have added an equation to calculate the outer widths of the trapezoidal segments.

 

[Peter Roan]

Is is definitely off the subject but I’ve gotten intrigued by tumbling bowl projects. As a new turner I’ve watched a bunch of you tube videos but I guess I need detailed step by step instructions which I have have found hard to find. Do you know of any sources?

Thanks for your posts

 

[Dennis J Gooding]

Sorry Peter, but I have I have never done a tumbling bowl and did not even know what it was until looking it up just now I expect that others here will be able to help you however. DJG

 

[James Penuel]

View: https://www.youtube.com/watch?v=EbMG44BuFNw

Woodturning - Tumbling bowl

 

[Robert D Evans]

I'm just starting to dip my toes into segmented turning. The turning part is easy. Cutting the wedges on a wedgy sled is easy. Gluing up the segments is not too hard either. Making the wedges the correct thickness and width so I don't run out of wood is the tricky part. I've got my first bowl drying up in the shop now. I learn something new every time I try it.

 

[Mike Adams]

You might be interested in this site: https://cdelker.bitbucket.io/segbowl/

It lets you design the bowl's profile in 3D and then adjust the particulars (segments, rings, etc.) and print out the requirements/cut list.

Things you can adjust:

• Drag and drop drawing of bowl profile
• Set thickness and number of segments in each ring
• Rings can contain segments of different arbitrary sizes
• Color individual segments or patterns of segments in a ring
• Generate a report of all dimensions and cut angles in fraction or decimal format
• Change units between inches and millimeters
• Rotate individual rings or "twist" for spiral effect

 

[Robert D Evans]

Thanks Mike. That's a great tool. I'll put it to use. I'm not really ready to spend a bunch of money on Segment Pro software...... yet. I just finished my 1st segmented bowl. I got the cut list from a Google search. It's 11 inches in diameter and has 97 pieces. Maple, walnut and purple heart. I think it turned out pretty well.

 

[Mike Adams]

Thanks Mike. That's a great tool. I'll put it to use. I'm not really ready to spend a bunch of money on Segment Pro software...... yet. I just finished my 1st segmented bowl. I got the cut list from a Google search. It's 11 inches in diameter and has 97 pieces. Maple, walnut and purple heart. I think it turned out pretty well.

You're right! It's gorgeous. That's the best free, online resource I've discovered. I visited another site not to long ago that had a very good method based on some printable 1:1 graphs where you'd draw the side plane of your design and then use a spreadsheet to generate the necessary cut measurements. As usual, I couldn't find that link when I wanted to share.

But this new one is better. At least for me. I'm not likely to spend a lot of money on buy-me software when this app does what I need.