INTRODUCTION TO WOODTURNING
Chapter 9: Spindle turning - setting up for practice
9.1 The blank
The most convenient timber to practise on is some kind of softwood. This has the advantage that it is cheap and readily available. The wood does not have to be of good quality. Old pallet wood, for example, will do nicely, and offcuts of floor joists can often be picked up on building sites. It is, however, best to avoid knots as much as possible because they are hard and create wild grain; as a consequence they are relatively difficult to turn.
Whatever wood is used, It should be cut to provide a blank about 2 in square by 12 ins long. Some turners, I believe, like to cut the corners off of a square to be used for spindle turning with a power saw or by planing. Normally, this is not necessary. Someone, I think it was Peter Child, said: "there is a machine designed to take the corners off, it's called a lathe".
9.2 Mounting the blank
Fit the practice piece between centres on the lathe. A two-prong or four-prong drive centre can be used at the headstock end. It does not greatly matter which, although I favour the two-prong. Alternatively, the suggestions I made in Chapter 5 (section 13) when referring to safety can be followed. If either four prong, or a ring centre, is used to drive the work care should be taken to ensure that the end is cut square so that the points or the ring will be in full contact with the wood. If a cone point, or a ring centre, is used then it will be necessary to use a revolving centre in the tailstock.
If a spur drive is used a fixed centre can be used in the tailstock but, if so, a blob of light oil must be dropped on the work-piece where the point will penetrate. This relieves the friction and prevents burning of the wood.
If the fixed centre is used care must be taken to tighten it up from time to time as the work progresses as may become a little loose in the early stages. If this is not taken care of the work-piece could fly off the lathe and cause injury; in any case it needs to be held firmly if turning is to proceed satisfactorily.
9.3 The rest
Before the rest is fitted for the first time the top edge should be examined carefully to make sure it is smooth and free from paint, grooves or notches which might impede a tool which is slid along it. If it is not free from these defects it should be filed smooth. It should be remembered that a chisel or beading tool will probably have a relatively square corner which can catch quite easily. To allow chisels to slide more easily it is a good idea to round off any sharp corners with a stone.
Once the work-piece has been mounted the tool rest must be set in position. It should be placed where it will be about 1/4 in clear of the revolving corners of the work-piece and a little below its centre. It is not possible to be very specific about the latter distance. I am often asked how high the rest should be; my answer is "where it is comfortable". The reason for this is that it depends on the height of the turner in relation to the height of the lathe. However, about 1/4 in should be about right to start with (see Diagram 9.1)
Diagram 9.1 The position of the rest for initial exercise
The point is that the rest should be in such a position that a cut can easily be taken whilst retaining the recommended stance (see Chapter 6). This should not create any heartaches as the position is not that critical. After a couple of passes of the tool the beginner should begin to get the feel of where the rest should be.
In carrying out the exercises described below consideration should be given to the length of the rest. Ideally it should be about 8 ins long. Anything less than 6 ins will mean that it will have to be moved frequently. Anything more than 10 ins and it may become unwieldy and, if it is not strongly made, it may flex at the ends. But the beginner will probably have to use whatever rest is supplied with the lathe.
9.4 Turning speeds
It is also necessary to consider the selection of speeds. When I am demonstrating I am often asked what speed I am using. That is a reasonable question but it is one to which I do not necessarily know the answer. When I was using my Coronet Major all the time I would not think about speed as such but I would consider the size of the work-piece and then decide which of the five pulleys was appropriate. Occasionally, perhaps because the work-piece was a little out of balance, or for some other reason, I would decide that the speed was wrong and then move up or down a pulley. Now that I am using a lathe with an electronic variable speed I simply turn the control knob until I judge that the lathe is turning at a suitable speed. Then, again, I may decide that some adjustment is required.
So where does this leave the beginner. It should be noted that the "correct" speed is determined by a number of features of the work-piece, such as the diameter, the width or length, the weight, the hardness and density, and the fibre structure. To add to this there is the variability of turners' techniques and the choice of tools and bevel angles. Even if there was such a thing as a "correct" speed, the actual choice is likely to be a compromise when there may be only three speeds available.
Please note, though, that even if it is not possible to choose the "correct" speed it is quite possible to choose the wrong speed. This is more likely to be too fast than too slow. I think it possible that many novices consider that high speeds (or the fastest practical speeds) are desirable. It is in fact much better (it is certainly safer) for the novice to err on the low side when choosing a speed. If that seems too slow he can then move up to the next speed.
The tendency to choose too high a speed not helped by the fact that some lathes on the market (or which may be purchased second hand) have a totally inappropriate range of speeds. (See the comments about lathes in Chapter 2.)
As he gets to know his machine, and his material, the turner begins to know almost instinctively how fast it should be rotating for a particular job. Often the sound alone will provide sufficient information. Consequently the experienced turner seldom thinks in terms of rpm or of cutting speeds. However, particularly in the case of the exercises described below, I will indicate the speed that should be used, where I think this is appropriate.