Pestle and Mortar
Monday 06 October 2008
Nick Arnull makes a sycamore pestle and mortar
1.The finished pestle and mortar
This pestle and mortar was requested by the kitchen commander - my wife Jane!
I did not want to make another round-bottomed bowl so this gave me a problem; how do I make a turned product that is not completely round?
The solution was to leave part of it square. An added bonus was that it would be more stable in the kitchen.
I kept the design simple as too much decoration provides an ideal home for germs and debris. I would also recommend using a tight-grained timber to avoid dirt traps such as sycamore (Acer), fruitwood, maple (Acer campestre) and beech (Fagus).
For the finish, I used vegetable oil as it is durable, it is readily available, and can be easily re-finished when it becomes grubby.
For this project, I chose to use English sycamore (Acer). For the mortar, the timber size was 150mm (6in) x 150mm (6in) x 75mm (3in). For the pestle, I used a piece of timber 150mm (6in) x 25mm (1in).
Glossary Rollover a term to view its definition
- Bowl Gouge
A cutting tool with a deep flute and a heavy cross-section. These are normally made from round bars and the flute is milled out. The round bar fits into the handle thus giving the tool a great deal of strength to enable it to overhang the toolrest a long way in order to hollow out deep bowls. Its primary function is for faceplate - or bowl turning - but it can also be used in spindle work. The bevel angle is ground to suit the user but is anything between 40 degrees and 80 degrees. Traditionally, bowl gouges are ground straight across, but many turners prefer to grind the wings back. There are many terms for a swept back bowl gouge - fingernail grind, O'Donnell grind, Irish grind, Ellsworth grind, lady's finger - to name a few. There may be subtle differences in these grinds, but generically they are all bowl gouge grinds where the wings have been ground back.
This is a circular plate that can be screwed to the workpiece and then attached to the headstock's spindle thread. When turning a bowl, the faceplate is screwed to the top of the bowl blank and when mounted on the lathe, enables the outside of the bowl to be turned.
As its name suggests, scrapers scrape the wood rather than cut it and generally leave a poorer surface finish on the wood than cutting tools. Unlike cutting tools, do not use the bevel rubbing technique with a scraper. In fact the 'bevel' is really a clearance rake and allows the cutting edge to come to a sharper edge. Sharpen or hone it often and take very light cuts with a scraper. You should get shavings; if you are only getting dust, resharpen it. Scrapers come in all shapes and sizes - square edge, round nosed, French curve, box scrapers and hardwood scrapers. The picture shows a 1/2 inch round nosed scraper.
- Spindle Gouge
Modern day spindle gouges are made in the same way as bowl gouges - from a round bar of M2 high speed steel with the flute milled out. The flute is shallower and more open than that of a bowl gouge. Traditionally spindles gouges were forged from a flat, rectangular sectioned bar and some manufacturers have started making a modern day version of this, commonly known as the Continental Style spindle gouge.
Like their name suggests, spindle gouges are used to cut details such as beads, coves and fillets on spindle work.
- Spindle Roughing Gouge
Spindle Roughing Gouge
This gouge is semicircular in section and the bevel is ground at between 35 and 45 degrees. The cutting edge is usually ground straight across. It is normally used in spindle or between centres turning for reducing a square blank to a round section - known as roughing down. This gouge is commonly known as a roughing gouge, but is more accurately described as a Spindle Roughing Gouge as it must not be used on faceplate work, e.g. for turning bowls.
PHOTOGRAPHS BY JANE ARNULL
health and safety
- Protect your eyes and lungs at all times, and work at a speed that you feel comfortable and safe
- Always reduce lathe rotation speed when using wood that is not round and alternative chucking methods that you are not familiar with
- Keep the tool rest between you and the work. Never let your fingers cross over to the other side
Diagrams Click an image to enlarge