Ellipical Cross

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TribalRR

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Here's my attempt at making an Eagle original design. It's a Sycamore cross in Bloodwood inlaid in Spalted Maple. After seeing an unturnded blank by Eagle, I know this one was made differently but only because I couldn't figure out how he did it...

As usual, my pic isn't great and it's making some illusion that makes the beams look different widths. I assure you they are the same. Let me know what you think. Thanks
 

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Hosspen

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Chip,
I think you did a great job on that. I like the way the Bloodwood picks up the reddish tinted spalted part. I like the symbolism of Bloodwood with the Cross too. A special pen!
 

Randy_

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Chip: I'm not very good at visualizing how a segmented blank will turn out; but in this case, I think I know what is happening. Don't know if I can put the explanation in words that will be understandable, but I'll try.

I don't know exactly the sequence of cuts and glue-ups that you used; but somewhere during the process, one of your cuts was not perpendicular to the crossarm. Cutting it at an angle caused the crossarm to "appear" thicker than it actually is. Maybe that will give you enough of a clue to understand the geometry, maybe not. Think about a skew and what it would look like in cross-section and then think about how much wider the bevel appears because it is ground on an angle and not perpendicular to the chisel.

I will see if I can make a little MS PAINT sketch to illustrate the idea and post it later.

Bottom line is you actually need to make the crossarm significantly thinner than the upright (or the upright a little thicker) if you want them to appear to be the same thickness.

If this is a little intimidating:confused:, I can help you out with the math and maybe draw up a plan for you on my CAD program. Email me if you would like some assistance.

Added: Click on the thumbnail and then click again to enlarge and click once more to display full size. Quality isn't so hot until you look at the full size drawing and even that ain't great; but maybe it will help you understand what I think is going on.:)
 

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TribalRR

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Thanks for the comments everyone!

Randy, I understand what you are saying, but both beams are perpendicular to the center axis. My first attempt was to drill at an angle to the center axis but this has more problems then the wider horizonal beam. That beam will also be curved and because your taking a cross section of a cylinder with a cylinder instead of a plane, the ellipse winds up kind of a curved triangle, neat but not what I wanted. The difference in widths that I was referring to is an optical illusion brought on by the different orientations of the grain. I used dial calipers to check after I saw the picture...
 

Randy_

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Chip: You are exactly correct, of course. With the benefit of a few hours sleep and your pointing out my oversight, it is fairly obvious. I can only revert back to the first sentence of my original post:

Chip: I'm not very good at visualizing how a segmented blank will turn out.....
At least that portion of my comment was correct!!:rolleyes: :redface: :rolleyes:
 
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