The Skew Chisel
Monday 14 September 2009
Nick Arnull takes a look at the skew chisel and its many uses
The skew chisel is a versatile and invaluable tool for any turner, and is almost exclusively used when turning spindles. It will plane, turn beads, make 'V' cuts, pummel cuts and turn long, shallow coves. It can also be used to create dovetails for various chucking methods. It is available in many forms and sizes from micro to huge: 3mm (1/8in) to 38mm (1 1/2in). Some turners prefer one type over another, but I personally recommend the 25mm (1in) flat/traditional skew chisel to all beginners as it is generally more stable and easier to sharpen. However, it will take more effort to master.
In this article, I will show you some simple exercises to help build an understanding of techniques needed when using the tool.
SharpeningThe skew chisel requires two bevels to be ground at a skewed angle. This appears to be easy to sharpen, but will require a steady hand to produce an even bevel on both sides.
Position your toolrest at the correct angle to the grinding wheel. Ensure that the bevel is completely in contact with the wheel and check the edge is parallel to the face of the wheel. Once the platform/toolrest is set, remove the tool, switch on the bench grinder and apply the tool to the grinding wheel, sliding it across the face to grind one even bevel along the cutting edge. Once completed, turn over the tool and repeat for the second bevel
Basic presentation to make a planning cutThe skew chisel should be presented 'toe up' at an angle to the timber handle, trailing away from the direction of the cut, allowing the bevel to rub against the timber with the tool supported at the corner rather than the flat areas of the tool; this being directly behind the point of the cut. The toolrest should be at a position appropriate for the size of tool being presented. It can on occasions be raised a little if turning small diameter spindles, but at no other time.
To achieve a cut, lift the handle and a shaving will start to appear over the cutting edge - often initially this appears as dust. Try to keep the handle in a position that feels comfortable. If you become tense while using a tool it will not flow smoothly along the timber/toolrest, so try to make fluid cuts from a relaxed position.
Control is gained in two ways: lifting the tool up and down (this will control the depth of cut) and by rotating the wrist (this will control the cut position along the cutting edge). Both of these movements are very small indeed and are more about feel and sensitivity. As turning progresses, the need to look at what the tool needs to do becomes intuitive. Feel is of utmost importance with the skew as the density of timber is felt more with this tool than any other. Always start at the centre of the blank working towards the ends.
Place the heel of the tool against the timber, toe up (in neutral). Lift the handle gently until you see dust starting to come over the edge of the tool: at this point the tool is beginning to cut. Lift it very slightly and you should see shavings starting to appear and gently start to travel along the blank until you reach the end
Here we can see the tool cutting at its sweet spot, or perfect position. This is never higher than the centre line of the tool or there is a high risk the toe will dig into the timber and make a glorious mess of the wood
Making 'V' cutsWhen making a 'V' cut using the skew, you must ensure that each cut must be made progressively wider. Ensure only to cut with the very point/toe of the tool, remembering to move the handle to each side of the 'V' whilst making a lifting arc as the tool travels into the wood
Using only the toe of the skew chisel, score a line to the left of the pencil line, going deep enough to score the fibres at the outer diameter of the blank and no more (if you go too deep the timber may well burn)
Now, move the tool to the opposite side of the 'V' and repeat the first cut, but this time going slightly deeper than you did previously. Continue as before working on one side, then the other, until you have gone as deep as is required
Turning beadsWhen turning beads it is important to try and achieve a balanced bead. Today, I still visualise a large balloon tractor tyre. Remember to only remove the material that is not required to create the finished bead and look carefully as work progresses to determine where the material needs to be removed.
It is amazing how little material actually needs removing in order to successfully create a bead; the centre is usually not touched at all during this process.
Start at the corner with the tool presented at a slight angle, and roll to the right-hand side. Do not start at the centre. Remove the corner using the point/toe of the skew. With one cut already made the bead is beginning to take shape. The tool should end up at right angles to the spindle and the edge should be vertical to the bed of the lathe. Next, do as above, but ensure to use the tool to blend curved areas with greater control
Make a second cut, but roll the tool more to the right whilst lifting the handle as it travels down the curve. At the same time swing the handle to the right for the right-hand side of the bead
Here you can clearly see the finish position of the tool still with the handle trailing to produce a slicing action as it travels into the wood. Now, repeat for the left-hand side of the bead but in a mirrored movement of the right
Making pummel cutsOne way of forming a pummel is to start by making a 'V' cut at the point where the transition from the square to the round is required. Mark a pencil line all round the workpiece where the 'V' cut is to be made. The 'V' cut itself is made in exactly the same way as a 'V' cut in a round section. Making the cut in the square blank is more difficult because the corners cannot be seen clearly; there is therefore a danger of chipping the corners. It may help to put something white on the bed of the lathe behind the workpiece; this may help to make the corners more visible. Note: the 'V' must be stopped immediately as the bottom of the cut forms a continuous circle around the workpiece. Having made the 'V' cut, the corners on the section of the workpiece beyond the pummel can be removed with a gouge, but take care not to damage the corners of the pummel.
Mark two lines on the face of the timber: this is the centre and outer corner of the cut. Here they are 10mm (3/8in) apart, usually made on two faces to allow a visual reference as the wood begins to rotate
Make the first cut to the right-hand side of the left-hand line as you would for a normal 'V' cut
Now, move the tool to the right and make the cut to the left of the right hand line
Repeat the first cut and move slowly back towards the line until it meets the point of entry
Repeat the cuts until the 'V'/pummel is to sufficient depth to break the square and make a complete round in the timber. Here you can see the finished pummel cut