Help with Math on a feature ring

dalegillaspy

New Member
I could use some math advice on a feature ring. I am trying to make a feature ring about 10.5" in diameter. The rest of the bowl is 24 segments. The key part of my feature ring will be square blocks as filler, such as in the Jerry Bennett video where he calls them ABC blocks, so the angled portions will be the regular blocks. My question is this....do I make a 12 segment smaller ring and use the blocks as filler to get me to the size I need? or do I make the 24 segment ring with a much smaller SEL to allow room for the filler blocks? The filler blocks need to be square because of the way I glued them up all in a strip and cut them apart. Does that make sense?
 

Lloyd Johnson

Administrator
Staff member
You have multiple options to consider. Let’s assume your are going to have 12 complex segments and 12 simple spacers. The worst option is to have all 24 of these segments angled and that takes much effort and harder to accomplish so I would eliminate that as an option. This leaves the option of 12 segments that are angled and 12 segments that have parallel side edges.

You can do these by keeping either the edges of either the complex or the simple spacers parallel. Either way, since you will be gluing a segment with parallel sides to a segment with angled sides, the segment with the parallel sides does not change the angle from what it would be if the parallel sided segment wasn’t used. Therefore the angle you will use to cut the angled sides with be fifteen degrees. The parallel sided segments simply space those angled segments wider to increase the outside diameter of the ring.

You can do this in either Segment PRO or Woodturner PRO. In Segment PRO, change the field labeled ‘Vertical Space to something other than 0 and then make sure the field below that field says to apply this to the Feature Ring only. As you do, you will see it in the Bowl View. You simply need to decide if the complex segment or the simple spacer will have the parallel sides and use the width of that segment as the width of the Vertical Spacer. This will generate the Segment Edge Length that the angled segment must be to create the ring with the desired outside diameter.

I personally would model this ring using Woodturner PRO, even if I was using Segment PRO to model the vessel. Simple create a single ‘Flat’ ring in Woodturner PRO and set it to 12 segments with the desired outside diameter and then change the Vertical Spacer field as desired. You can then click on the Segment View to see what that ring would look like after gluing it together. By using Woodturner PRO, you can easily do what-if scenarios because that software only follows your instructions.

I hope that helps,
Lloyd
 

dalegillaspy

New Member
Yes, that actually makes a lot of sense. I guess I need to play more in the software. I seem to be trying to run before I can walk, but I came up with a great design idea for a friend's Christmas gift and couldn't figure out any way to do the feature segments except in a long row then cut them off in slices. I'll go play in Woodturner pro then post a pic when I get it done.

Thank you,
Dale
 

Lloyd Johnson

Administrator
Staff member
When in Woodturner PRO, look at the ring in two different configurations - first, the ‘Flat’ as I described and when you then look at the Ring View, you’ll see what it looks like if you glue the simple angled segment to a parallel-sided block.

Then recreate the ring using the ‘Wheel’ ring type. This simply changes how you glue the segments. Although it is a simple change, it has big differences when you do the turning. In the Flat model, the complex segment is off-center whereas in the Wheel configuration, the complex segments as well as the angled segments are oriented correctly to the center of the turning. The Ring View will show this.

When turning, all segments not centered on the center of the bowl will give unpredictable results if the wall profile changes by more than a little bit. The Wheel configuration eliminates this negative effect.

While this effect is there if the vertical spacer is narrow, it is typically not noticeable and that is why this configuration is used most commonly. If the vertical spacer is your complex segment done in the Flat configuration, it absolutely will be noticed.
 

Lloyd Johnson

Administrator
Staff member
Here's an illustration of the same ring using the Flat configuration and the Wheel configuration. It really is a difference in the way the segments are glued together. If you just glue the complex spacer to the end of each simple segment, you get the Flat configuration. But if you shift the postioning of the segments while gluing, you get the Wheel configuration.

It's a small change but has big implications.

Flat configuration:
flat.jpg
And the Wheel configuration:
wheel.jpg

In both cases, the complex segment is angled and the simple spacer has the parallel sides. The spacer isn't drawn as you would cut it except for the parallel sides. You can see how the Wheel configuration orients all segments to point to the center where the Flat configuration does not.
 
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dalegillaspy

New Member
very interesting. Thank you for all of that. I think for this one it is going to have to be the complex segments with parallel sides and the simple segments angled. If I can pull that off in wheel configuration and make the simple segments be the angled ones it is going to be the best as I would like the front face of the complex segment to be distorted as little as possible.. I'm working on the glue up for the complex segment now....I'll post pics when I get something actually turned.
 

Lloyd Johnson

Administrator
Staff member
Great. Keep track of the time it takes to make a feature ring using the ‘Stacked Wood’ method you are now using. Then I’ll work with you to make a feature ring to make a thunderbird design using Lamination PRO. It should take less than half the time.

I look forward to seeing the pictures of your finished product.
 
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