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segmenting books (Read 1,661 times)
 
Don Andrews
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segmenting books
Oct 3rd, 2017 at 7:39am
 
Hi Can anyone recommend any good books on segmenting for beginners? I am  an experienced turner of about ten years, but I am just working on my first segmented turning. I have Malcolm Tibbetts book the art of segmenting, good book however it is the university course, I am looking for the highschool text and project book Smiley

Don
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Re: segmenting books
Reply #1 - Oct 3rd, 2017 at 8:45am
 
Is there an area in particular or style that you want to focus on.
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Don Andrews
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Re: segmenting books
Reply #2 - Oct 3rd, 2017 at 10:17am
 
I am currently working on a staved beer mug. I have cut and glued the staves, rounded the out side and started holling the inside to round. I had it mounted for this operation in a flat piece of MDF with a recess cut to fit the outside Dia. and glued with hotmelt and supported with a one-way spindle steady, but the hot melt didn't hold need to reglue with yellow wood glue? My chuck is a Nova SN2 but I have only the factory jaws that will hold up to 2.5 inch tenon, need jaws that will hold 4 inch. I plan to make the base of a flat laminated walnut, tenoned to fit inside.
In short I am looking for books that give small simple segmenting / staved projects with mounting suggestions in order to gain experience. Hoping to add some segmented trim rings to jazz up my projects. I find I learn best by following instructions on a couple projects untill comfortable adding my own twists.

Don
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Bruce Kamp
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Re: segmenting books
Reply #3 - Nov 19th, 2017 at 11:42am
 
Depending on the diameter I tend to use cole jaws on my SN 2 for holding stave projects.
I try to first hold to wide diameter then turn the narrow to accept a tenon. Glue the tenon piece in then turn it round. Then I reverse the piece and turn the other part.
I don’t mean for it to sound simple but I have just found that cole jaws help me a lot.
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Jenny Trice
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Re: segmenting books
Reply #4 - Jan 26th, 2018 at 6:53pm
 
I am interested in hearing the answer to Don's question too.  Mostly looking for what angles to cut pieces at for various projects.  Anyone with book suggestions??
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chris lawrence
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Re: segmenting books
Reply #5 - Jan 26th, 2018 at 8:42pm
 
Not a book but i use wood turner pro for all my segment projects.  Once you learn the software its pretty easy to design and it gives you a cut list with all the needed angles.  Its free to try for 30 days and $75 to buy if you like it.  I think its well worth the investment.
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Re: segmenting books
Reply #6 - Jan 29th, 2018 at 9:16am
 


I use Malcolm Tibbetts book a lot “ The Art of Segmented Turning.”  It provides a lot of really helpful information and tables in the back for angles etc.
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Grant Wilkinson
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Re: segmenting books
Reply #7 - Jan 29th, 2018 at 1:17pm
 
Jenny: Take a look at Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register.

Denny's videos go into a lot of detail on design and segment size/angles.
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Ray Stubbs
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Re: segmenting books
Reply #8 - Feb 20th, 2018 at 4:32pm
 
Segmenting Simplified

Since there are numerous questions about segmenting for bowl making, I have outlined the steps below to simplify the process.

The first step is to draw a sketch of the bowl. This sketch is drawn to true size of the bowl. See sketch below, S1.  Notice the centerline on the left side of the page with a cross section of the bowl. If this cross section is rotated about the centerline, then you have a bowl.

Now make a decision on how many segments there are going to be in each ring. This is important because of cutting the segments on the correct angle. As an example, I am choosing 8 pieces to the ring. All the rings in this bowl will be constructed of 8 pieces. I chose 8 pieces because on the weggie sled, it is easy to set these angles. There are triangles you can buy that makes this set up easy to achieve. I highly recommend using a weggie sled on the table saw for cutting the segments. It is accurate and easy to set up.

Now let’s look at the third ring, counting from the bottom up. If the segment rings are drawn as shown in S1, then you have the information needed for cutting the segments. This ring will be at a height according to the thickness of the wood in previous rings as shown in S1. There are 4 items of information needed.

1: T see S3
2: R is measured see S1. Simply measure from the centerline to the outside of the ring.
3: W see S1 and S2, W can be measured in S1.
4: L needs to be calculated but T, R, and W are all measured.
(Notice S2 is a view of the segment looking down from the top of the page as indicated by V1 in S2.)

Now it is time for a little math: There are 360 degrees to a circle, so divide 360 by 8 (no. of segments in a ring) and it is 45 degrees. The 45 degrees is the inclusive angle of the pieces to be cut. (See sketch S2). Note: Take that 45 degrees and cut each end of the desired piece at 22.5 degrees as shown in S2. Different numbers of pieces in a ring such as 6, 8, 12 etc. can be used and triangles needed can be found to set the weggie sled. Other numbers may be more difficult to set on the weggie sled because of finding the triangles needed to set the sled.
When doing a vessel use the same number of pieces in each ring.

The only thing left is L which is calculated. Notice in S2 that R and W are the same R and W shown in S1 and this represents the radius and width of the segment. L/2=Rx(Tan22.5 or .414). Then L=2x(R x .414)
Notice Tan 22.5 is for 8 segments to a ring. If there are 6 segments to a ring, then Tan 30 degrees is .577 and 12 segments to a ring, then Tan 15 degrees is .268. Notice that Tan no. goes down with the increase number of segments. This is high school trigonometry.
I didn’t put numbers in for T, R or W because my drawing for the bowl wasn’t to scale. You would want to draw your sketch to scale so that you can measure those features.

Once T, W and L for each ring are measured or calculated, the cutting is ready to begin. Remember the placement of the rings on the sketch depends on the thickness of the wood being used. Each ring can be a different thickness.
When gluing the pieces, do two pieces at a time then the pairs can be glued. On each pair, assuming it is a 8 segment ring, check the angle of two pieces with a square since it is 90 degrees or 2 x the inclusive angle. When the 4 segment pieces are glued together, it is a 180 angle, or a straight line. If it is not a straight line then adjustments need to be made by sanding on a disk sander.
When the rings are glued, then the top and bottom of the ring is parallel to each other and flat on each side.

When gluing the different rings together, they need to be concentric to each other and the joints need to be staggered, so 4 joints do not meet at the same place.  Every other ring the joints should line up with each other.

From S1, notice that the bottom ring has a hole at the center. That is because to get the segments to come to a point is difficult, so the bottom can have a plug.

There is a discussion on this Forum about how to do the bottom. For this discussion I won’t go into that.

Comments and critiques are welcome.


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« Last Edit: Feb 20th, 2018 at 5:38pm by Ray Stubbs »  
 
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Grant Wilkinson
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Re: segmenting books
Reply #9 - Feb 21st, 2018 at 7:07pm
 
Ray: Yours is a good explanation. The only thing that I would add is how to determine W. As I would think you would agree, there is really no math to do here, as it is very much up to the turner. For example, if the final wall thickness of the bowl is 1/4" and the turner wants 1/4" on both the inside and the outside of the final bowl to be safe when turning the glue up, then W would be 3/4". However, that is only true if the wall of the bowl was straight. Using your picture, and taking the segment R3 as an example, if you took the segment out 1/4" from the outer wall at the top of the segment and 1/4" out from the inner wall at the bottom of the segment, clearly you would be adding more than 1/2" to the 1/4" wall thickness owing to the curve in the wall.

In terms of L, I use a simpler approach. I'm not saying that using the tangent function isn't more accurate, but I give up a bit of accuracy in favour of simpler math. Using a drawing like yours, I find the diameter of each ring. The circumference of a circle is pi x diameter. So, for an 6" ring, for example, the circumference is 6 x 3.14 = 18.84 ". Using your 8 segments per ring, I divide 18.84 by 8 = 2.355. So the long side of each segment in that ring would be 2.355", The short/inside side is determined by the angle of the cut.

When I do my drawings, I like to use graph paper with 1/4" squares. That way, I can draw my segments and simply measure the width of each ring of segments.

I have done up an excel spreadsheet with the formulas coded in, so I simply need to input the ring diameters and all else is done for me. I have another one for open segment pieces that does the same thing.

When I started doing segmented pieces, I did use 1/4" inside and outside as my allowance for turning. With more experience, I'm down to 1/8" or less. I'm using 1/4" here only as an example. Some will use more, others less.
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« Last Edit: Feb 21st, 2018 at 7:16pm by Grant Wilkinson »  

Grant Wilkinson
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Ray Stubbs
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Re: segmenting books
Reply #10 - Feb 22nd, 2018 at 9:43am
 
Grant some good points there. I appreciate your comments, and like the spread sheet method before going to the saw. We just need to be careful with the thickness of our wood. Because it would determine where the rings are placed on the drawing.
First W is a measured feature. As we draw a rectangle line to cover bowl section, we would draw the inside verticle line about 1/4" past or toward the centerline so we have enough material and you could leave maybe 1/8" on the outside. Then measure W with a scale. Now the reason for the extra material on the inside of the cross section of the bowl is, if you look at the cross section in S1 that verticle line is in the middle of the segmented piece. So on the corners of the piece, when we turn, we need more material at the corners of the joining pieces.
Now lets look at your approach to determining the length of a segment. From your description, if you need a 6" ring, this is the outside diameter of the ring, or flat to flat of the hexagon, you take the circumference of the a 6" ring by multiplying 6" by Pi. Then you divide that circumference by 8 (number of segments in the ring) and you get 2.355" for the long side of the segment.
If I use your numbers and work the problem backwards to see what the actual size of the ring in question. I would solve, Tan 22.5 = (2.355/2)/R and solve for R. This R would be the radius of the ring. Solving for R we get 2.842 and times 2 we get 5.685". That says our ring now is 5.685" instead of the 6" ring we disired. This may get us in trouble with not having enough material on the outside of the bowl section.
The trigonometry approach as I described in the original post is a proven method and will produce the exact size of the desired ring.

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Re: segmenting books
Reply #11 - Feb 22nd, 2018 at 2:47pm
 
Don

If you wish I have a few DVDs and four books on that and would loan them to you.  Just PM me with your mailing address and you can borrow them for a few months.

Also a lot of info on youtube about it also.
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Re: segmenting books
Reply #12 - Feb 23rd, 2018 at 8:14pm
 
Along with this segmenting construction, it's important that we have "Dos and Don't" with our construction work.

1. Don't mix hard and soft wood in the same project. You may not notice   any problems until you get to the sanding. Sand paper will cut more aggressively on soft wood than hardwood. This will cause waviness on the surface and the more you sand the worse it gets.

2. When you atempt to make the rings flat and parallel, don't use a planer. Planers like to cut with the grain not across the grain. Your ring will jump up and down and it will not be pretty or parallel. The best method is a drum sander or use your lathe to make the ring flat and parallel.
3. Before cutting the strips for "W" to the appropriate width, make sure your saw is cutting perpendicular to the table. The best to achieve this is, cut the end of a 2" high board off, then put a square from the botton and the cut, hold it up toward a light and see if the light is consistant across the cut.

There are probably many more that I have not mentioned.
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Ed Weber
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Re: segmenting books
Reply #13 - Feb 23rd, 2018 at 9:38pm
 
1. The mixing of soft and hard woods can be done but it does take knowledge and skill to achieve. I would not recommend for a new turner.
2. A thickness planer (and jointer) cuts downhill, with the grain not against, period. if you don't know this you probably shouldn't be using this type of machine. JMO
3. Adjusting your tools before a job should be natural, almost subconscious task.

The  more accurately you mill your stock before you start cutting segments the better the outcome will be. Do not assume that boards, like those that come from big box stores are flat, square and parallel.
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