8. Types of turning

Oval turning - Square turning - Twist turning -Cabriole legs

A friend of mine, who knew that I made quite a few salad bowls asked me to make her an oval one. This is possible, of course, with a little ingenuity, but I would not recommend it for the beginner. However, we can do oval turning between centres as we can do other things. Hammer handles come in this category.

Oval Turning. First of all, take a 2 in. square of wood about 12 in. long. Mark and drill a true centre hole at each end of the wood. On either side of the true centre mark and drill two small off-centre points at each end. A good idea is to draw a line with a pencil along the centre of each side. This will serve as a guide whilst turning. Mount the work in the usual way using two corresponding off-centres as centres. Before switching on the motor, turn the lathe by hand and adjust the tool rest to your favourite height, making sure that the corners of the wood do not foul the tool rest. Start your lathe up turning out a speed of about 1,500 r.p.m. which is fairly slow for anything around 2 in. in diameter. Do not be alarmed if a certain amount of vibra­tion sets up. This is because the wood is off centre and consequently out of balance. Remember, you are now deal­ing with a square piece of wood which is rotating off centre, so take care where you put your fingers.

For the initial rounding off, we must have the 3/4 in. gouge, used as before. Commence your cut about 2 in. from the tailstock, with the gouge twisted slightly on its right side and pointing slightly towards the tailstock. Remember to keep the bevel of the gouge rubbing the work.

Continue rounding off as previously described but only as far as the pencil marks running the whole length of the wood. Finally, smooth this off with the skew chisel, using the widest chisel you have. Wide chisels are much easier to use for this operation than the smaller ones. Only half of the actual cutting blade must be in use, and that the heel end, always with the bevel rubbing the work. If you use more than half of the chisel watch out for the point digging in. If it does, you will have to start all over again. Remove the work from the lathe and remount using the opposite pair of off-centres, the lathe still running at the same slow speed. Round off the work as before up to the pencil line.

Again remove from the lathe, and remount on the true centres and using the f in. half round gouge and taking a light cut, remove the sharp points of the pencilled ridge line. Finally, sand paper nice and smooth.

The same process is adopted for tapered oval turning. The wood being first squared up and centre lines being drawn from end to end and off-centre points marked. The larger diameter portions are turned to shape first.

Square turning. I am mentioning square turning only as a point of interest as it is hardly a practical proposition for our type of lathe, but you may have seen some examples of it in old houses, in the form of balustrades or as decoration on old clocks and mantelpieces, and have wondered how it was done. Although the pieces are not truly square but slightly rounded, it is, nevertheless, known as square turning. First of all, the number of lengths of timber required for the same design are squared up with a plane. A specially pre­pared drum is fitted to the headstock and a similar one to the tailstock. These drums have a wide groove turned in them on one side, to the width of the prepared squares of wood. The lengths of prepared timber are then fitted into the grooves of the drums and between both centres, enough lengths being inserted until the whole assembly forms one long continuous drum. The tailstock is tightened up and locked so that all the timbers are securely held between centres. Alternatively, the lengths of wood to be turned are clamped around the outside of the two drums, sufficient lengths being fixed by metal bands, until the whole of the circumference is filled in.

Now you have some idea of how the turning is done, and no doubt, your first thought will be that all these lengths of timber, when turned, will not be truly square on these sides, but slightly rounded, and this is where the impracticability of this type of turning comes in. If we are to have the finished lengths of timber with almost flat sides, the turning drums will have to be of a very large diameter, far greater than the swing of most of our lathes. Owing to the large diameter of this set-up, the lathe is run at a slow speed and turning commenced in the usual way and the whole length turned to pattern and sanded. The lathe is now stopped and the tailstock slackened off and this end of the drum removed. All the pieces of timber are then given one quarter turn and refixed between drum centres and turning re-commenced to the same pattern. A very accurate template is required for this process. This sequence is repeated for all four sides of the timbers, until all the turning is completed. Each operation is a separate job and must be properly sanded and finished for each side.

You have all seen tame mice on an endless route march inside a wire drum with wooden ends, well this looks very much like our square turning machine.

Twist or spiral turning. This is done in the trade by a specially constructed lathe which only does this one opera­tion. The wood is slowly rotated and advanced over a rotat­ing cutter. This method is not at all a practical proposition for the amateur, so we shall have to go back to the old fashioned hand method, which is only turning in so far as the wood is first made uniformly round over the required length by normal turning methods between centres. The lathe is then stopped and the spiral marked out. The easiest way to mark out the spiral is to wrap a piece of narrow adhesive tape round the work from end to end to give the required spiral.

If your eye is not too good for symmetrical shapes, a good plan is to draw a pencil line straight from end to end of the work, then divide your length of wood into a number of equal portions pencilling these points around the work. Now wrap adhesive tape or string around the work in a spiral, commencing at the first point where the circular marks cross the pencil line running lengthways, and con­tinuing around the work to the next point where the straight and circular pencil lines cross. Continue along the length of the marked work in this manner and you will have a set number of equal spirals. If you require only one long spiral from end to end, it will only be necessary to mark the half­way point along the work, so that your spiral is even. A pencil mark is then made on the work along the whole length of one edge of the adhesive tape. The tape is then removed. You should now have a pencilled spiral around the work to enable you to carry out the next operation, which is straightforward carpentry.

With a tenon saw and the wood still held in the lathe between centres, make a saw cut to a depth of f in. along the whole pencil line, slowly turning the wood by hand whilst continuing the saw cut. A good idea is to clamp a piece of wood to your tenon saw to form a depth gouge, so that your saw cut will be of uniform depth.

Two further pencil lines are now made, one on each side of the saw cut and at a distance of 3/8 in. from it, although this depends a lot on the size of the work undertaken. Now take the work out of the lathe, clamp it to your bench or in a vice and commence to chisel out a V-cut, using the pencil lines as a guide and to the depth of the saw cut. You will soon notice the spiral beginning to take shape, but take care not to cut anything off the top of the spiral or this will reduce the overall diameter of the work. Now, round the spiral with a wood rasp or coarse sand paper wrapped around a piece of wood endways, to keep the spiral a uniform thickness. Finally, remount the spiral in the lathe and, rotating the work by hand, finish off with a medium and fine grade of sand paper.

For the more ambitious, there is the double spiral, but again, you must be something of a carpenter as well as a woodturner, to complete this. It is merely two spirals twisting around each other. First of all, lay out the marks as in the single spiral, but the sections will have to be twice as large. Draw a second line running lengthways on the opposite side of the work to the first and mark your spiral as before, starting on the pencil line. The remainder of the work is carried out using the tenon saw and chisel, as in the single spiral.

If you really want to make a masterpiece, the same process is adopted for three or four twists. A further advancement is the hollow spiral but it is not practical for a single twist as the appearance would not be symmetrical, a double twist being the most attractive. Plot your double spiral on the work as before, preferably dividing your work into four equal spirals. In the plain double spiral we had three lines forming the spiral, the centre one being the position of the saw cut. Instead of using a tenon saw, we shall use this line as a drilling line.

At this point, it will be best if the work is held in a V-block to ensure accuracy in drilling. With a brace and bit, or better still, a portable electric drill, if you have one, use a 1/2 in. bit, drill holes half-way through the work along both saw cut lines. Using chisels and rasps and plenty of sand paper, the twists are finished off to shape, taking care to keep an even shape throughout the length of the twists.

During the whole operation of spiral or twist turning, the lathe is only used as a holding device and a great deal of skill and patience is required to attain perfection.

Needless to say, not many turners today take up spiral turning as it takes far too long to complete compared to normal turning, when articles can be made much more quickly. Spiral turning is best carried out using close grained hardwoods, such as walnut, maple, beech, etc.

Fluting and reeding is another decorative effect which can be applied to turning, although the work is only turned to its basic shape on the lathe, which is then only used to hold the work, the reeding being done by ordinary carpentry. With the wood held in the lathe, the part to be reeded should be divided into a number of equal parts around the work. If your lathe is fitted with an indexed head, that is a disc fixed to the headstock which has a number of equidistant points marked on it, marking out is quite a simple matter. Another way, is to wrap a piece of paper around the widest part of the turning, cutting the ends so that the paper just meets around the work. Remove the paper and, by folding, divide it up into a number of equal portions marking the folds with a pencil. Replace around the work and transfer these marked points on to the actual work. If the work is tapered, repeat this process for the narrow end, making sure that the marked points are in line with one another. This can be simplified if a pencil line is drawn centrally lengthways along the work. Parallel lines are then drawn connecting all the marked points.

The work should now be held either in a wooden vice or in a specially prepared box and the reeds carved out using normal carpentry tools, working from the large diameter to the small so that you are not cutting against the grain. If you intend to do a lot of reeded work, this can be done with the work held in the lathe and a portable router mounted on a jig running parallel with the bed of the lathe but this is probably beyond most of our needs.

Whilst dealing with work which is only part turned, we must not overlook the club-footed table leg or cabriole leg. For the club foot, the work is mounted between centres and turned leaving a portion of the work, nearest the head-stock, square. The foot of the leg, which will be at the tail-stock, is turned to shape and sanded, the very end of the wood being made true. The tailstock is removed and the work remounted 1/2in. off centre at this end of the leg only. The headstock centre must not be altered. As the wood is off centre, and consequently out of balance, you must make sure your work is held securely between centres. Also reduce the speed of your lathe to about 1,500 r.p.m. for this type of work, of about 2 in. in diameter. With a 3/8 in. gouge the heel of the club foot is turned to shape, then using a 5/8 in. half round gouge, turn the remainder of the work, starting at the foot end, taking care to hold your tool firmly, as at the commencement of shaping, the tool is not in contact with the work all the time. Continue with the 5/8 in. gouge, shaping the leg so that it is tapered from the foot end and gradually meeting up with the plain turned portion of the leg nearest headstock. With the lathe still running at medium speed, the leg is then well sanded with varying grades of sand paper.

Figure 17. Turning a club foot showing position of centres.

Plate 1 (above): The use of a gouge to shape the outside of a bowl.

Plate 2 (below): The angle of the gouge when commencing to hollow a bowl.

Plate 3 (above): The bowl almost completely turned on the inside.

Plate 4 (below): One method of laminated work. Note position of hands and gouge.

Plate 5 (above): A scraping tool in use, palm upwards.

Plate 6 (below): Rounding a large bead with a chisel. Note cutting action of point of chisel.

Plate 7 (above): The use of a template board when marking a cylinder of wood.

Plate 8 (below): Marking the basic features of the design with a parting tool and template.

Plate 9 (above): A parting tool in use.

Plate 10 (below): A long hole boring jig in use. Note the removable tailstock.

Plate 11 (above): Method of holding a tool in rounding a cylinder. Note the

If preferred, the wood can be cut to the rough shape of the leg by means of a bandsaw, but the method from then onwards is the same. gouge on its side.

Plate 12 (below): The position of the gouge in shaping a small hollow.

Plate 13 (above): Various types of boring tools: (A) parrot nose (B) centre bit (C) counter borer (D) and (E) forstner bits (F) shell auger (G),

(H) & fl) twist bits.

Plate 14 (below left): Designs for table lamps and floor standards.

Plate 15 (below right): Polishing work between centres. Note position of hands.

Plate 16 (above): Designs for a candlestick lamp, candlesticks and serviette rings.

Plate 17 (below left): Turned cruet.

Plate 18 (below right)' Simple laminated work.

Cabriole or Queen Anne leg. Turning these legs is very much like the club foot except that the wood must be first cut to shape by means of the bandsaw. In making the leg, the profile shape is first laid out on two adjacent sides of the wood. Now mark the centre of the foot and put a corres­ponding mark at the other end of the leg. This we will call the No. 1 centre. Mark another centre at the extreme heel of the leg and put a corresponding mark at the other end. You should now have two centre marks at each end of the leg.

The work is now mounted between centres on the lathe, using the No. 1 centre line. The toe and fillet are first turned taking great care not to remove too much wood. You will note that this type of leg can only be turned at the foot end, the remainder being shaped with conventional carpentry tools. The second pair of centres may not be required, but on the other hand, they may help in cleaning up the external part of the toe. It will be found more convenient if the work is left in the lathe for the final finishing with spokeshaves, rasps, etc.

Small feet made in the same manner as in the club-footed leg are very useful for giving the base of a floor standard lamp more stability. For all off centre turning you should use a good, hard, close-end, straight grained wood, for example, mahogany, walnut, sycamore, beech or maple.

The Queen Anne leg is a good example of strong wood being used.

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