Club Night Report
Wednesday 9th August 2017
Club Night Report for 9th August 2017 - observations by Vernon Hughes
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Jason set to work without delay and mounted a 1" thick by approx. 8" diameter Maple blank on a screw chuck initially, but this was just for the purpose of explaining how such a method would lead to small but unacceptable (for this quality of item) splits to the timber's fibres. The blank must start flawless (dry, well-seasoned, no cracks) and be maintained in that state throughout. He has developed his own solution to holding in such circumstances. This involved making a circular carrier from two differently sized circles of plywood the smaller of which is held in large (say 4") chuck jaws after the blank has been fixed to it using a pan head 'furniture bolt' in a 4-prong captive tee nut. It draws the blank and carrier together with maximum holding efficiency, and the flat surface of the carrier leaves no mark on the surface in contact. After truing the blank's edge to a perfect circle a narrow parting cut was made immediately outside the rim of the central retaining bolt-head, the point being made that this provides a critical measuring reference. Dividers were used to mark exactly the width of a semi-circular hollow to be cut to create the inside of the box. Jason then briefed us about the means of achieving the perfect hollow by using pre-prepared circular testers/ templates of sizes selected for purpose (e.g. 38 mm) marked with a diameter line. He started hollowing with a fine bowl gouge and then switched to a magnificently ground, round-nosed (negative rake) scraper to perfect the inner curve, which was tested frequently to get it spot-on. The scraper in practised hands produced the finest of shavings. On completion of the hollow the next task was to face off the surface. This was done with a scraper the blade of which was held in hand (not the handle) and the thumb was used to gently push the scraper across the essentially perfectly smooth toolrest. After taking specific measurements very carefully and precisely to ensure perfect accuracy in shaping the opposite side of the blank Jason emphasised that care should be taken during sanding to slow the lathe speed, and to avoid rounding of interior corners. With the inside of the box and surface preparation now complete the work was reversed (on the faceplate) using the same centre bolt holding method and work commenced on what would be the outside surface(s) of the box. Now is seen the crucial importance of measurements. The distance from the edge of the blank to the starting point for the rounded outside wall of the box is critical. Shaping was started by defining and cutting the width of the outer rim to a specified thickness, followed by shaping the outer wall of the box in a fine curve to match the internal curve maintaining even wall thickness throughout, and finished by shaping the central area immediately outside the head of the retaining screw. A clever notch in the holding faceplate facilitated the entry of the callipers used to check the wall thickness. Jason advised that if an edge is to be rounded to create a design feature then this should/ could be done with abrasives. A diameter line was then marked deftly freehand in pencil at remarkable speed, to mark the line of sawing the circle in half. The sawing was done with a fine quality Japanese hand-saw, but can be done at the bandsaw working slowly and deliberately.
Next was the gluing together of the two halves which must be done with absolute precision. Then came the making of two decorative rings in African Blackwood to be mounted at the mouths of the body to form collars into which the two lids would fit. The question of glue suitability for various timbers was dealt with in detail.
This part of the demonstration was supported with a PowerPoint presentation covering ingenious techniques, jigs and equipment that Jason has devised for achieving perfect results in a field where accuracy, stability and quality of finish are critical to the end result. The adaption of four conventional chuck jaws to make a small set of Cole jaws for holding the collars aroused gasps of appreciation from some of our own elite turners, as did his cramping system when gluing the two halves together. Tool edge forms including negative rake scrapers, and grinding/ sharpening methods were explained in detail. Designs for this type of box and methods of work for creating them were also covered in detail, routing, texturing and sand blasting all coming into play; and a design for a stand (needed with only some designs) was also explained. How ordinary mortals are to acquire the certainty of touch and clear-headedness necessary to make these wondrous examples of the turner's craft is a question yet to be answered. As Arthur observed at the end we had been absolutely captivated and enthralled by all we had witnessed and heard; it had been a wonderful evening (quite literally). We applauded at least twice...
Footnote:
Towards the end of his demonstration Jason conveyed the disturbing information that many of the great timbers especially Rosewoods, the availability of which we have been able to take for granted including the commonly used and inexpensive Bubinga, were now to be banned from use, perhaps to the same level as ivory. This is due to China swallowing up huge quantities of the world's limited supplies of these magnificent timbers to the point of rendering them rare and endangered species. Yandles (may) still have some stock advised Jason.
This month's Show and Tell was: A Kitchen Item
| A conventional design pestle and mortar from Richard Branscombe was awarded third place |
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| Second place went to David Branscombe with a palm style pestle |
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| Placed first was a circular breadboard/ presentation board in beech by Harry Rock |
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