A friend who runs a restaurant in Aberdeen seeded the idea of a table for a Sunday brunch environment; somewhere to read newspapers, drink coffee and meet people. She had seen it in Germany and enjoyed the experience, so why not here in Aberdeen? Space was limited so the idea of a table which could be reconfigured sounded attractive. Could I do something?
Out of this idea came Segment 1, a table made as one of three segments of a circle based on an orange segment. As each standard place setting is approximately 60 cm wide, the diameter would have to be at least 2.5 metres for the full circle. It turned out to be 3 metres.
Above is the finished product. Perhaps this could be my statement piece?
I prefer working in solid material rather than veneer, as it gives that distinct quality feel if the piece is well made. For a circular table using these materials, expansion and contraction will have to be accommodated, particularly in the high stress environment of a restaurant. From an aesthetic point of view the 1:5 scale development model showed that the corners of the segment panels were most convincing if they were curved, so I had to come up with a method to cut these curves. The radial grain direction should work to reduce the risk of cracking but would need extra strength around the perimeter to support vertical loading. How do you glue up a radial piece - cramps are not made in that way.
There were many other challenges which are for another article, or a beer.
The materials were pippy oak for the panels, sycamore for the frame and fumed oak for the outer rim. The pippy oak and sycamore were supplied by Julian and Malcolm at Angus and Mack, and the fumed oak came from my own air dried stock.
Sufficient vertical strength came from 1” steel tubing, inset around the edges, as in figure 1 and photo 2. Glueing each tube in its centre to the table frame or panel allows the wood to expand and contract independently of the steel. A small allowance was needed at the end of each tube for heat expansion.
The method for cutting the curves in the matching panels lent itself to a template system with a router and bearing cutters as shown on figure 2.
However it would not be good enough to cut a line through ply and sand it off because the thickness of the blade would introduce a major inaccuracy. A master template and inverse master template was needed as shown on figure 3.
Looking at my collection of 1/4” router cutters and the Wealden catalogue, I found a wide enough selection to do the job outlined below.
To make the matching templates, I made the master template using a bandsaw and sanders. The master template is green in the diagrams and smoothness and squareness of the edges is the critical point. Using a 16mm guide bushing and a 12.7 straight bit, I made a guide template as shown in figure 4 by running the bushing along the master template and using the outside edge of the cutter to do the work. The guide template is shown in yellow.
With an improbably sized 11.1mm cutter (7/16” from wealden) and a 40mm bushing I used the guide template to cut the inverse master template running the bushing on the guide template and the inside cutting edge of the bit as on figure 5. It worked for me and felt somewhat miraculous when the two templates fitted snugly together. Photo 3 shows two template pairs used for the table and photo 4 shows one in use.
There are limitations to this method; for example the thickness of the templates has to be greater than the guide bush length - 10mm ply is OK for this; the inverse template cannot have curves with a radius less than 20mm which in this case was not a limitation.
For those interested, this method works because the gap between the bushing bearing surface and the cutting edge of the two combinations of cutters and bushings is the same - 14.4mm. There are other size combinations which can overcome these limitations but this worked at the scale of my table. I have subsequently found out this is not the only way of carrying out this operation.
Photo 2 and and 5 show the results of the work of these templates.
A special table for assembly and glue up was essential for a piece like this. It allowed the top and central leg to be worked together when glued. It could also be used as a clamping surface for the radial panels, with wedges and blocks. Photo 6 shows it in use.
The table is now installed and well loved by staff and customers in our local bistro www.buchananfood.com, here in Banchory. It is showing some signs of heat stress at the end of one panel, which has required strengthening from below. 6mm feathers attaching the panels to the ribs were not strong enough right at the extremities. The three coats of lacquer are standing up well to the constant use.
It was an intense 5 weeks to build this and deliver on time for the exhibition (excluding the modeling). In hind sight based on the performance of the table over 3 years, I would work with dryer wood - say maximum 8% moisture content, so the table was only dealing with expansion for it to stabilise its moisture content - tension is not so easy to accommodate.
Power tools are essential to make this in the time available. But because of the fine tolerances for the templates, they were used more like hand tools. Each cut was planned and tested to ensure it would all fit together perfectly.
Please contact me if you try these methods and let me know what it enables you to do. IT has gone open source on many occasions and it’s something the furniture makers world is starting to get used to.
14th August 2015