Designing a Segmented Vessel

In this article, I will explain how to make a set of plans to create a segmented Vessel.

I want to thank my good friend and mentor, Jim Burt from Knox City Texas for providing the information and encouragement for this project. Items in quotation marks are taken directly from a paper written by Jim.

The only tools you will need are a pencil, an eraser, a ruler and a sheet of paper large enough to create a full scale model of what you want.

In addition I like to use a digital caliper.

Just a couple basic terms that segmented turners use.

The length is how long the back edge of the segment is.

The Width is the board width when you start cutting.

The thickness is how thick your ring will be.

I know it is pretty basic, but it is easy to get the thickness and width mixed up.

The first thing you need to do is decide what you want to make.

I suggest you start with something small.

The video link is to a YouTube video that I made covering all aspects of how I Design and Build a Segmented Vessel.

Begin by drawing a vertical line in the center of your paper a couple inches longer than the height of your vessel.

After that, draw horizontal lines to correspond with the thickness and number of layers you have in your vessel.

Sketch the outer edge of your vessel. I am usually pretty generous with the thickness of the wall.

You can always make an eighth inch wall from a quarter inch wall, It's pretty hard to go the other way.

Draw vertical lines on both sides of the wall. When first starting out, I suggest you add a bit extra.

You can use a ruler to measure the width of the segments in that ring. The bottom one can be skipped if you plan on using a solid piece of wood for the bottom of your vessel.

I prefer using decimals instead of fractions when using formulas.

To find the outside radius of your vessel (R_out), measure from the center line to the outer line of the drawing.

To find the inside radius, (R_in) measure from the center line to the inner line of the drawing.

(R_in) = Inside Radius of the ring.

(R_out) = Outside Radius of the ring.

(C) = Circumference of the ring.

(N) = Number of segments in each ring.

(W) = Width of the segments in that ring.

(L) = Length of the segments in that ring.

(A) = Segment angle.

(CA) = Segment cut angle.

(BL) = Board length. This is the minimum length of wood needed to cut the segments in that ring.

C = 2π(R_out)

Ring 1 (R_out) is 4.8 inches. Circumference of ring 1 would be C=2(3.14)(4.8) which equals 30.144

I will not go through the rest of the calculations at this time.

A = C/N = Segment angles.

CA = A/2 = Cut angle.

In this example our vessel will have nine 3/4 inch layers and will have 24 segments in each layer.

If you are using a table saw, you will only need to know the angle of each segment.

To find the angle of each segment, divide 360 by 24 = 15 degrees.

If you are using a chop saw or band saw you will use the Cut Angle, which is the above angle Divided by two.

The cut angle would then be 7.5 degrees.

W = (R_out) –( R_in) = Width of each segment.

To find the width of each segment, simply subtract (R_in) from (R_out)

The inner radius from the outer radius.

Width of ring one would be 4.8 - 3.0 or 1.8 Inches.

You will need this measurement for each layer.

You can also just directly measure the width of each segment; I use the above formula when I made the included Excel Spreadsheet to cut down on the number of variables needed.

L = C/N = Length of each segment.

To find the length of each segment you need to divide the circumference of each ring by the number of segments in that ring.

The circumference of ring one is 30.144 inches.

Divide 30.144 by 24

L = 30.144/24 = 1.256

BL = N*L

The board length is the minimum length of material you will need to cut the segments for that ring.

To find the board length multiply the length of the segment by the number of segments in that ring. (N*L)

In this example it would be 24*1.256 or 30.144.

To compensate for the width of the sawblade, I usually add an additional two or three inches to each board so I have plenty left over after cutting each segment.

"Be aware that BL is the minimum board length from which these segments can be cut. Make your board longer so you can trim cracks off the ends, cut around knots or other imperfections, cut extra segments or simply make a mistake or two☺."

Updated link to Excel File to make Cut Sheet.

Not sure what I'm doing wrong.

To get a copy of the spreadsheet, you will need to copy and paste the Link below and it will take you to a page that will allow you to download the spreadsheet.

https://southplainswoodturners.weebly.com/uploads/5/3/2/3/53231531/segment_calculator.xlsx

To make a cut Sheet, download the Excel file and open it.

Using the answers to the formulas from your sketch enter the inside radius (R_in) and the outside radius (R_out)

The spreadsheet will make all of the calculations for you.

Simply print it out and start building.

If you are interested in making more exact cuts here is a list of the formulas needed.

The following formulas use diameter instead of radius.

A = 360/N

L = D_out*tan(A/2)

W = [D_out – D_in*cos(A/2)] / 2

B = 90 – A/2

BL = N*L – (N-1)*W/tan(B) + (N-1)*K/sin(B)

I would like to again thank Jim for all of his help.