Monday 08 September 2008
Nick Arnull copy turns an hourglass
1.MAKING THE SPINDLES: Centre both ends of all spindles. Cut to round using a 19mm (3/4in) spindle roughing gouge. Using a storyboard, mark the layout
Following on from last month's article on simple copy turning, I am now going to show you how to make an hourglass. I have chosen a classic design that is stable and would equally look good as an ornament.
We have a daughter who plays many instruments. Like most parents in this position, nagging about levels of practise often leads to tension so I decided to make her an hourglass, a 30 minute timer she can use for her practise. She is currently studying towards her diploma in classical clarinet and after music college, she hopes to teach and intends to use this piece to time her lessons.
This project is all about repetition and creating multiple components that appear to be the same as each other. The answer is to get the key dimensions identical so that when assembled, they appear to be exactly the same. If you look closely at hand- turned stair spindles, they will be similar but not identical.
I chose European walnut for this project as it is dry, stable and easy to turn and as time passes, you will notice that it ages superbly.
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.
- Parting Tool
As the picture shows, there are several different types of parting tool - three of which are shown here. On the left is a narrow (3mm) parting tool which is very useful when parting work where the least amount of grain mismatch is desirable, for example when parting the lid from the base in box making. The middle tool is a straight sided, standard parting tool and the one on the right is a diamond parting tool where the widest part of the tool is at the cutting edge. This can be advantageous when cutting deep grooves because it means less of the tool is rubbing on the sides of the groove. Parting tools primary task is to part wood off in spindle work but they are also used to cut tenons or spigots and grooves. They can also be used to cut beads.
- Skew Chisel
An extremely useful tool but has a reputation for being difficult to control. Certainly you can get some nasty catches with it but it is worth mastering. It is used mainly in spindle work and produces a very fine finish from the tool, requiring little, if any sanding. Planing cuts, peeling cuts and slicing cuts can be made with the skew as well as turning beads, coves and 'V' cuts.
Typically, the cutting edge is ground at 60 degrees to the axis of the tool - hence the term 'skew' and the tool has two bevels whose inclusive angle is anywhere between 25 and 45 degrees.
Skews are now made in three styles - rectangular section, oval section and rolled edge section.
- 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.
Like the headstock, this is normally made from cast iron or fabricated in steel. It is designed to slide along the bed and be clamped to the bed in its chosen position. The method of clamping it varies between manufacturers, but a common clamping method is by means of a cam locking assembly. The tailstock houses the quill or barrel, which in turn houses a revolving centre, allowing spindle work to be supported.
- Protect your eyes and lungs at all times and work at a speed you feel comfortable and safe
- When turning accurate spigots, use a spanner to get them spot on. When drilling through wood, clamp it to the table using a base board to achieve clean holes with no break-out on the underside
- When assembling the project, apply small amounts of glue applied with a small brush to reduce any seepage
- Various glass timer designs are available. Sizes vary so adjust dimensions to suit your glass size. Glass timers are available from Turners Retreat
Diagrams Click an image to enlarge