A Woodturning Masterclass with Dennis  Keeling RPT

Segmented and Composite Turning

At the Wight  Woodturners autumn Demonstration Day professional turner and author Dennis  Keeling presented a Masterclass on Segmented and Composite Turning.  During this fascinating day Dennis showed us  how unique pieces could be turned from composites constructed from segments of  wood and man made materials bonded together as these examples show.           

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An open segment bowl A polychromatic bowl An offset Corian® bowl

Dennis  is from Great Missenden in Bucks where his well equipped workshop is along side  an Art Gallery and shop run by his wife Lyndsey.   Details of his website may be found in the Resources section below.  Turning has been a lifelong interest for  Dennis who spent most of his working career as an Industrial Engineer and  Software Specialist.  These very  structured disciplines are certainly evident in Dennis’s approach to his unique  brand of segmented turning.  Dennis  became interested in this form of the craft in the late 1990’s and his many  achievements since then can be seen on his website.

During the demonstration day  Dennis showed us how to construct and turn bowls with both closed and open  wooden segments, a polychromatic bowl made of plywood and tinted Perspex and  one of manmade Corian®.  As building the  composite ready for turning is 80% of the work and usually spread over several  days, Dennis showed us by means of slides and short videos how to construct the  composite.  In true Blue Peter fashion he  had prepared several beforehand and then he showed us how to complete the  turning.

Here  are some photos taken on the day.  Just  double click anywhere on any of the small pictures to see a larger image.  There are additional notes on some of the  details with the pictures and a list of useful resources, including tools and  materials, included at the bottom of this page.           

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Dennis gets underway  telling us about his background and turning interests
He tells us all the    “advantages” of segmented turning -                                                        some don’t need convincing!
A very attentive audience  watches!
Dennis outlines the simple  process to make a wooden segmented bowl

All  the detailed steps for a closed segmented bowl are shown in Dennis’s book  “Segmented Turning – a Practical Guide” – page 81. Alternatively, a slideshow on “Simplified  Segmented Turning” can be viewed on Dennis’s website – see Resources 3 below. Included in the slideshow are the block  diagram of the bowl in section and the sums for the segments, together with  diagrams on how they are arranged.  To  see photos of each step of the segmented construction, with notes, have a look  at the Woodworkers Institute article – see Resources 4 below. The techniques  for making an open segment composite start on page 101 of the Segmented Turning  book.

Dennis  recommends using a chuck mounted wooden faceplate on to which the solid base of  the bowl is attached by a glue and paper joint. The closed segments are best  glued end-to-end using a high grab glue such as Titebond II which is ideal for end  grain bonding. The ring layers are best glued together with a white PVA which  allows movement for alignment of each completed ring. For open segment  construction PVA is best as the end of the grain is not glued.

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Dennis explains the difference  between “closed” and “open” segmenting
A completed closed  composite ready for turning. Note the paper/glue joint between the base and the  wooden faceplate
Dennis always turns the  inside first so that the fragile structure can be supported while the outside  is turned
Here, the inside of an open  bowl, previously hollowed out, is being carefully finished with a teardrop  scraper
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Now, the top MDF support  ring that was used with the lathe steady when turning the inside, is being  removed with a BG
Dennis now separates the  paper/glue joint with a knife and a quick tap.                                           The paper quality is crucial!
Dennis uses a stepped  conical jam chuck to support the inside of the open composite
The outside is now gently  shaped with a BG. With the lathe stopped you can of course see the exact wall  thickness!
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For final finishing Dennis  uses a negative rake scraper, freshly ground, for a superb surface
Now the base has been  cleaned up (never neglect the base!!) and any glue in the gaps carefully cleaned  out with a file
The finished bowl straight  from the lathe. There would also be a sanding stage but not in a live Demo!
Some of Dennis’s work

After lunch we were shown how to make a  Polychromatic Offset Bowl.  This was a birch  plywood and coloured Perspex composite with the layers tilted at an angle of  45º to give a “bull’s-eye” effect.  Again  the full details may be found in Dennis’s book (page 120) or alternatively as a  slideshow with notes on the Woodworkers Institute website with a link in  Resources 5 below.  The key to success in  this project is using the correct adhesive to bond the rigid plastic to the flexible  wood which can move.  A flexible CA glue  works well, for information see the Resources 10 below. Dennis recommends  lightly sanding the shiny Perspex surfaces with 120 grade to provide a key for  the glue.

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Dennis explains the steps  to construct a polychromatic composite
“Here’s one I prepared  earlier” Note top MDF support ring and the wooden faceplate
Here the top support ring  is trued up and made to fit the jam chuck
The jam chuck is accurately  aligned
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The bowl is now reversed  and the outside turned
 
Reversed again! The inside  cleaned up and MDF support ring removed
The base has been parted  off and the bowl re-fitted to the jam chuck to provide axial alignment but  without any radial forces
After final finishing  (and sanding) our polychromatic bowl is complete                                     

For  the final demonstration of the day Dennis took us through the steps to make an  Offset Corian® bowl.   This is where wood gets abandoned altogether for this bowl is 100%  synthetic.  Corian®,  made by DuPont™, is a solid, non-porous, material composed of 1/3 acrylic resin  and 2/3 natural minerals. The material which is inert and non-toxic is  considered food safe. It can be worked like hardwood and using similar tools. Corian®  is used for kitchen worktops and surfaces which need to be kept hygienically  clean. Off cuts can be obtained from kitchen fitters.  All the steps to make this striking bowl can  be found in the Segmented Turning book (page 167). Also there is a detailed slide  show with excellent photos on Dennis’s website - see Resources 6 below and a  Woodworkers Institute article – Resources 7.

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Dennis uses a 2 part  coloured Corian® glue to bond the layers (not easy to come by). CA may also be used

Here’s a composite ready  for turning. The inside has already been turned and finished
The outside is turned using  a tungsten carbide tipped tool. As Corian® can produce sharp splinters  when turned eye protection and gloves are a must
As before, the nearly  finished bowl is carefully aligned for final finishing. Can the CL4 alignment really  be this bad!!!
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The final finishing with  the negative rake scraper.
The finished shape,  still to be sanded and polished. Just polished – no additional finish is needed
Some finished work and some  still in progress
Dennis’s variable offset  shallow bowl. Now there’s a challenge Derek!

To  round off the day after the lathe work Dennis took us on a tour, with the aid  of a slide show, through some of his other segmented creations. This showed us  how the pieces were constructed and finished illustrating how Dennis’s work has  developed and is still developing.

So, from this  interesting day you can see the vast range of skills and techniques Dennis uses  throughout his segmented turning. Once  you start down this segmenting road folks, you will never again be bored!!

Wight Woodturners express their grateful thanks to Dennis for a fascinating and entertaining day.

Some additional  resources for Dennis’s Masterclass

1.
Dennis Keeling’s website – full of  interesting info. Website link
2.
Book “Segmented Turning – a Practical  Guide” by D Keeling is available here  Website  link  or  Website  Link
3.
Simplified Segmented Turning  - DK slideshow Website Link
4.
Woodworkers Institute article “Your  first segmented bowl” Website Link
5.
Woodworkers Institute article  “Polychromatic Bowl” Website Link
6.
Turning with Corian  –  DK slideshow Website Link
7.
Woodworkers Institute  article  “Offset Corian Swirl Bowl” Website Link
8.
Open Segmenting Template Details here  and Details here
9.
Titebond 11 glue Details  here
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Flexible CA glue  -   Starloc Adhesives “Clear “N” Tuf” Details here  and  Details  here
11.
What is Corian®  ?  Details  here
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CA glue for bonding Corian® - (Isaac Lord Mitre   Adhesive) Details  here
13.
Tungsten carbide tipped tool    (Simon Hope) Details here  Partway down the page
14.
Tungsten Carbide tipped tool   (Hunter tools) Details here  and Details  here
Peter Smart - November 2012