Offset Sculptures archive
Thursday 11 March 2010
Adrian King presents two different options for making an offset sculpture from maple
My first attempts at lathe sculpture were fairly straightforward from the turning point of view. So, wanting to develop the theme in a different direction, I sought inspiration from other art forms.
Glass, ceramics, nature, architecture and modern abstract sculpture are a never-ending source of ideas, which can be adapted by using plain, offset and multi-axis turning, together with carving, piercing and texturing. So, it is always worthwhile being in a receptive frame of mind when visiting museums and craft exhibitions - keep a notebook handy.
This piece is a response to a book I read about the sculptor, Barbara Hepworth, whose works often feature smooth rounded forms, which are hollowed or pierced using a variety of different methods.
There are TWO variations of the form described here, so it is best to study the complete project and make your choice of mounting before any work is started. Note: Option 2 requires drilling before any turning is carried out.
Option 1 is truncated and stands vertically. Option 2 is drilled at an angle and mounted on a stand. It also has an offset tip, which can be at the upper or lower end, or both.
Tools used10mm (3/8in) straight-grind bowl gouge, spindle roughing gouge, round skew, 12mm (1/2in) Continental spindle gouge, 15mm (5/8in) spindlegouge, 10mm (3/8in) round skew and a selection of carving tools
For both options you will need a maple square: 96 x 250mm (3 3/4 x 9 3/4in) for Option 1 and 96 x 280mm (3 3/4 x 11in) for Option 2. Mark the maple square out with centre lines on the faces and diagonals on each end of the piece
Fot Option 2 onlyStep 2
For Option 2 only, set the drill table at 45 degrees and clamp the maple square firmly, but loose enough to allow final positioning of the drill accurately on the marked centre line and aim for the centre of the block. Use a 15mm (5/8in) Forstner bit to get an accurate bore - check the fit on a scrap piece beforehand, to make sure it fits. Take fast, light cuts until the bit head is fully engaged and continue drilling to a depth of around 50mm (2in). This may seem excessive, but some depth will be lost later
For Options 1 and 2Step 3
Needed for both options, this dolly, to which the maple block will be glued, is made from a scrap piece of ash turned between centres to form a 'doughnut' at one end and a series of flanges - the central one being the size to fit your chuck - and a flat face at the other. It can be held square in the chuck for normal turning by gripping the flange in the jaws, or offset and gripped by the 'doughnut' to allow the block to be worked at an angle. The 'V' grooves give a better grip and can also be used to gauge the angle, while the flanges can be located inside and outside the jaw dovetails to aid stability when the piece is angled
Using the centre point on a side face, draw a circle the size of the dolly to locate it. Fit the dolly square in the jaws, apply strong glue and cramp with the tailstock. Mark a recess to fit your largest chuck jaws. Keep the right hand point of the divider well clear of the spinning square, as you will be cutting air in two places. Cut the recess with a round skew
Using a 10mm (3/8in) straight-ground bowl gouge, dish the area inside the recess to a depth of 20mm (3/4in) leaving a small flat for the jaws to seat onto. Sand the dish through the grades at this point, then seal and polish. Do this at this stage as it will be difficult to do so when the piece is angled
Take the profile of the hollow so it can be replicated on the other side
Loosen the chuck and reposition the piece for the offset drilling. Butt one of the flanges of the dolly against one jaw and swivel into position before re-tightening (see step nine)
Position the piece so the outer edge of the 38mm (1 1/2in) sawtooth bit held in the tailstock is on the centre line and touches the wood about 15mm (5/8in) in from the edge of the hollow. Run the lathe fairly slowly and take delicate cuts until the whole of the cutter is below the surface, then drill normally to within a centimetre of the other side
Sand the bore through the grades using abrasive wrapped around a cylinder, keeping your hands well back. After sanding, apply several coats of sealer and remove the dolly from the workpiece. A filling knife is kinder than a chisel and leaves a better surface. Reverse the work using the recess made earlier, hollowing out to a depth of 20mm (3/4in). Things may get a bit bumpy as the bore is revealed, so take lighter cuts and check the profile. When the bore is completely exposed, check again with the profile gauge, sand the hollow and remove any drill marks left in the bore by hand sanding and then seal
It is now decision time, as there are mounting options to be considered (Options 1 and 2)Step 10
Mount between centres, rough down to a cylinder, then change to a continental spindle gouge and take light cuts to clean up the central portion of the cylinder, paying particular attention to the edge of the hollow to keep it crisp, then taper the ends down to 50 mm (2in). Note: the circular dishing is now oval
Use the continental and spindle gouges to turn one end to an oval profile. I chose the end having the central bore nearest to it â€“ the shorter end. The very long 'pip' here was necessary to get rid of a nasty nail hole!
Option 1Step 12
After sanding and sealing, saw off the 'pip' and remove from the lathe. A pull saw is ideal for this job. Use a chisel and a sanding pad to clean up the end
Protect the finished end with masking tape and reverse it into a scrap chuck
The base is undercut with a spindle gouge, then sanded and sealed. This completes Option 1, apart from applying a wax polish, which I left until the end to allow me easier handling
Making the offset tipStep 15
Mount the piece of wood between centres and repeat instructions for step 10. Form a wide cove to form the 'fishtail' which will be cut to shape. When you are satisfied with the shape, sand through the grits and seal, then repeat step 11
To make the first bandsaw cut, it is necessary to stabilise the piece. Push the drill you used to make the 45 degrees, mounting the bore back into place, and rest it on a block to keep the piece steady. Put a pad under the central hollow to protect the surface
Make the first cut to shape the fish tail of the offset sculpture
The first cut is now complete, as you can see from the photo opposite
Cut off each side of the 'fishtail' keeping the piece upright and continuing the line of the main section. Raise the piece continually as the cut proceeds, so that the wood is always in safe contact with the bandsaw table
When the sawing is complete, refine the shape with a carving tool. The initial shaping is now complete and the hand finishing can be started. For final smoothing use a cabinet scraper, then sand down to 600 grit, followed by medium and fine Webrax or similar and several coats of sanding sealer, de-nibbed and waxed
At this stage, it was time to think about the design of the base. I decided to rule out anything with curves, even those echoing the lines of the piece, as I felt they might detract from the simplicity of the design. I decided to mount the piece on 15mm (5/8in) copper tube, which would tone well with the maple and also with the wedge-shaped piece of bubinga - 120 x 50 x 25 mm (4 3/4 x 2 x 1in) - a plain but interesting shape, which I found in a scrap box. Drill a 15mm (5/8in) hole 20mm (3/4in) deep at a slight angle to give it a backward tilt, which shifts the centre of gravity of the whole piece and gives more stability. Finish the bubinga with the cabinet scraper, fine abrasives and webrax, then seal and wax
Mount a 100mm (4in) length of copper tube between a spigot and the tail centre, and clean with fine emery and/or wire wool and metal polish. Wash off all traces of polish and apply a coat of clear lacquer to prevent tarnishing, but avoiding the ends, which will be glued
Finally, glue the components together, find a good spot to display it and then go in search of other shapes you can adapt for a lathe sculpture project. Go hunting! The sculptures are now complete