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HOW TO FIND SAGMENT LENGTH AND LEVEL WIDTH IN SEGMENTED BOWL

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Blog entry by Sam Shakouri posted 08-28-2011 09:07 AM 2033 reads 7 times favorited 9 comments Add to Favorites Watch

Here I’m again to show you the second part of my blog.
To start with this, you need a life size plan. First thing to do is drawing parallel horizontal lines represinting the thickness of the timber you intend to work with, each zone represents one level or (ring). Devide it in half with a vertical line to represent central line. SAY, your bowl is made of 4 level, each level 12 segments. Draw your bowl within 4 zones, number them 1 to 4, ( you may need to draw only half of it as I do in my drawing here). Next, draw 2 lines on each level to represent the width of level. Some tolarance spaces have to be added for any mistake.
Further down, draw 2 crossed lines meet at a point on central line, at 30 degrees. Now use the compasses to measure the outer radius of each level and draw a line to conect the crossed lines. that curve represents the length of segment when the bowl is turnd. The real length that you need is the stright line that conects radioses and tuches the circumference. So,the end of the story is A- life size plan, B- the brocken line is the width of the segment and the red line is its length. Hope it is clear enuogh to the job.
ADDITIONAL INFO:
It is very difficult to cut the segment in level #4 with clean cut and make all segments meet at one point, as the saw will leave some damage to that 30 degree corner. The solution is to make a design advantage of this problem by drilling or cut a big hole in the centre and re-block it with a disc of the same timber or even different kind and coloure timber. AND then the problem is solved for a better look !!

-- Sam Shakouri / CREATING WONDERS WITH WOOD.....Sydney,Australia....



9 comments so far

View TopamaxSurvivor's profile

TopamaxSurvivor

14742 posts in 2328 days


#1 posted 08-28-2011 11:25 AM

That seems simple enough. What if you wanted to do 8 segments? use a 45 degree angle?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Sam Shakouri's profile

Sam Shakouri

980 posts in 1740 days


#2 posted 08-28-2011 11:54 AM

Not 45 but 67.5 degrees or 22.5 depending on which side you are reading. You have to read my previous blog, anyway.
45 degree angle is for square frame. I did not mention this angle in my previous blog because it is very common with pictures framing.

-- Sam Shakouri / CREATING WONDERS WITH WOOD.....Sydney,Australia....

View Bob Collins's profile

Bob Collins

1536 posts in 2336 days


#3 posted 08-28-2011 12:25 PM

Good information Sam, nice and clear and easy to follow as with the previous blog. Thanks for sharing.

-- Bob C, Australia. I love sharing as long as it is not my tools

View TopamaxSurvivor's profile

TopamaxSurvivor

14742 posts in 2328 days


#4 posted 08-28-2011 10:29 PM

I saw the previious blog. I am wondering what angle you use on the sketch to give the lenght of the segments. 67.5 and 22.5 will be dramatically different lenghts, or am I missing it totally ? ;-))

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Sam Shakouri's profile

Sam Shakouri

980 posts in 1740 days


#5 posted 08-28-2011 11:03 PM

The angle inside the segment is 67.5 degrees. But some people want to read it from outsid where you move the miter from 0 ( or 90) degrees to 22.5 degrees, just because there is no 67.5 dgrees on any miter. Thanks Topa for commenting on both parts of my blog.

-- Sam Shakouri / CREATING WONDERS WITH WOOD.....Sydney,Australia....

View Bearpie's profile

Bearpie

2587 posts in 1670 days


#6 posted 08-28-2011 11:38 PM

Picture is clear to me and I grasp the concept of the layout. I am working on my second segmented bowl now. Thanks for clarifying the concept, I truly do appreciate this help!

Thank you very much!

-- Erwin, Jacksonville, FL

View Grumpy's profile

Grumpy

19455 posts in 2503 days


#7 posted 08-29-2011 02:30 AM

Sam, saw some of your mates at the Oyster Bay shed last weekend. They do some nice segmented work as well.

-- Grumpy - "Always look on the bright side of life"- Monty Python

View Sam Shakouri's profile

Sam Shakouri

980 posts in 1740 days


#8 posted 08-29-2011 07:06 AM

It was my plan to go there, but I found Macarthur had BBQ on Saturday and our monthly meeting on Sunday.
Hope you had a good time over there. Thanks Grumpy

-- Sam Shakouri / CREATING WONDERS WITH WOOD.....Sydney,Australia....

View Tootles's profile

Tootles

704 posts in 1154 days


#9 posted 08-29-2011 12:52 PM

Topmax

I think what you are asking is what angle you would use for an eight sided bowl in place of the 30° shown in the lower sketch of this blog. Is that right? If so, yes that would be 45°. If you refer to the previous blog where I did a sketch, the angle that you need in order to draw the sketch above to calculate segment length (not segment cutting angle) is determined by dividing 360° by the number of sides of the shape.

-- I may have lost my marbles, but I still have my love of woodworking

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