By Camilla Harmston.
Saturday 18th August was in the diaries of many of our members as a day to look forward to. Especially pertinent to the newer turners, but a good refresher for many of the more senior members, Peter Williams had planned a half day tree to bowl demonstration.
Peter has been turning for around 18 years, starting off using files adapted into scrapers. One day he went to see Ian Fish, who looked at the bowl Peter had brought along and asked him why he didn’t learn to ‘cut’ the wood instead of just scraping it. Ian showed him how to use a bowl gouge and managed to sell him a couple into the bargain. Peter currently lives up in Kerikeri and is very fond of Pohutokawa, creating many of his pieces with this wonderful sea-smelling timber.
Peter had brought along a length of Pohutokawa and showed us how, once ready to process into blanks, it is useful to take a slice off the log with the electric chainsaw so that the pith position can be easily noted. Peter then cuts straight down through the pith and either cuts the log into a round using the chainsaw, or uses one of his circle templates, nailed onto the bark of the half log, and cuts a nice neat round with the bandsaw.
Once he had his bowl blank, he attached a faceplate with the appropriate length screws and then mounted the blank on the lathe. It was a good opportunity to use the screen that Jamie had made which prevents all manner of matter flying at the riveted audience!!
Peter gave a brief overview of sharpening, including the angles he prefers for his bowl gouges (one at 35° to allow bevel support on the inside of a bowl and one at 55° which he uses on the outside), and his advice to use a sharpening jig to ensure repeatable grinds without removing too much steel. The minimum tools he feels are a good starting point are a bowl gouge, a parting tool and a skew.
He touched on form versus function and suggested that it doesn’t really matter whether form is following function or just as a form of art. Peter’s personal preference is for a catenary curve which is the curve a hanging flexible wire or chain assumes when supported at its ends and acted upon by a uniform gravitational force, and he feels that it is not so much the shape that is important as the transitions from one curve to another. Another important design feature he considers is where the base appears to sit if the eye follows the curve. If it is above the surface the piece is resting on it gives a sense of lift and appears as if the piece is floating.
Peter demonstrated body and tool positioning to ensure the best possible cut as well as discussing lathe speed and went on to rough out the bowl and create a chuck bite. The bowl was reversed into the chuck, the face cleaned up and then Peter began to hollow out the bowl. He pointed out that it is possible at this point to make an internal chuck bite so that when the piece has dried it can be remounted and the external spigot cleaned up for finishing.
It is important to put the date, the type of wood, and the weight, once the piece has been roughed out and removed from the lathe. Peter then recommends sealing and placing the piece somewhere cool, with an even temperature and no sun for drying. Once the piece has stopped losing weight it is ready to finish.
Once the piece is dry it is mounted back into the chuck – Peter had a previously dried piece to demonstrate this, and he advises sharpening the tools at this point for as clean a cut as possible.
Inside, outside and rim were finished before Peter power sanded through the grits from 80 to 400 and then used 0000 wire wool. He used a nitrocellulose sealer, painting this on with the lathe stationary and then used the wire wool to de-nib. He made sure there was no wire wool left on the piece by wiping with toilet roll and then polished with his preferred Australian ‘Old Bucks’. He did suggest just using a food-safe oil for anything that is to be used for food.
Talking of food, we all enjoyed a tasty BBQ and scones thanks to Bob and Jane, and some cake from Paula – all in all a satisfying morning of good fuel for bodies and minds!