Constructing Jigs For Batch-Producing Three-Legged Stools

Les Symonds makes a popular item using a series of jigs and aids to simplify construction

If there’s one item I repeatedly get asked for at my woodturning shop, it’s a three- legged stool and I guess that I’ve made about 50 in the three years since the shop first opened. In the early days I tried a few different designs, but once I realised just how popular they might be, I decided to settle on one, giving the stool my own features and making it financially viable to reproduce.

I soon came to realise that the way forward for me was to standardise my design so that I could batch-turn components, but then also realised that it would make sense to design and make a series of jigs so that the component parts could be replicated accurately and independently.

The thinking behind my design is one of clean simplicity. The top is a straightforward disk with the legs socketed into tenons rather than drilled through and wedged. The bottom of each leg is turned into a partial sphere/ball, allowing it to sit well on the floor without the need to mark out and cut an angled end, as is the case with square-ended legs. Each leg has a straight taper throughout its length, with its upper end having a half-cove and second taper into its tenon. Beyond that, there is a little decoration on the leg, comprising a bead atop the ball and then two scorch lines higher up, just to echo the lines around the bead. So I gave the design the name Bead & Ball.

Health and Safety

There are a few H&S matters to bear in mind with this type of project, both in the use of the jigs and in the making of the stool. In any drilling operation, securely holding the workpiece should be paramount, but in this case we also have the jig to consider. When drilling the leg sockets, both the jig and the workpiece must be secured. When forming scorch lines, never use a scorch wire that does not have handles attached to it. I have a range of gauges of wires and each has a wooden ball attached to each end.

The four jigs

The stool’s components

I favour close-grained hardwoods such as beech (Fagus sylvatica) or sycamore (Acer pseudoplatanus), straight-grained for the legs, although I occasionally use a piece of timber with more complex grain for the top. My standard design is of a 300mm x 225mm stool, thus it needs a 230mm- diameter top out of stock to finish at no less than 30mm thick. While still in-the- board, this would be finished on one side, through a thicknesser or table sander, then cut into 23cm disks on the bandsaw. This finished side of the blank will become the underside.

The legs are exactly 300mm long out of square stock to finish at about 36mm diameter.

Making the stool-top jig

The jig for turning the top is extremely basic. It is simply a disk of a stable hardwood, so avoid any irregular grain patterns or pieces of timber with variations in density within them, such as pieces which incorporate both heartwood and sapwood, splits, cracks and/or knots etc.

It needs to be thick enough to support the stool top and to have a recess cut into it for mounting into a chuck – mine is about 25mm finished thickness. Its diameter needs to be 30mm smaller than the blank for the stool top, so I cut mine at 200mm. To machine the recess in the jig for the chuck jaws, I mounted a chuck on the lathe with 10cm jaws in it, held the jig against the tops of the jaws and then brought the tailstock up against it to press it into place. With the workpiece revolving, the outer edge can then be cut square to the face, the toolrest turned through 90° and then the recess for the chuck jaws can be cut. I made my recess just wide enough for the jaws to slip into it, so it can therefore be used with the chuck either in compression or in expansion mode.

With the recess cut, mount the jig into the chuck jaws and clean off the outer face, ensuring that it is either completely flat or very slightly dished, preferably no more than a millimetre or two. You now need to mark three holes to accept the fixing screws, which will go through the jig into the underside of the stool top, at the locations of the leg sockets. With the jig still mounted in the chuck and the toolrest in place, use a pencil to mark a 18cm-diameter circle on the face of the jig. Around this circle we now need to make three equally spaced pencil marks, so this can be done by using the spindle lock or indexing head – if you have either of these – or by the good old-fashioned way of describing arcs with a pair of compasses. Take the jig out of the chuck and drill through each of the three pencil marks with a 4mm drill turn the jig over and drill a countersink into each hole to accept the head of an eight-gauge screw. The jig is now ready to use.

Accuracy

Accuracy is an essential aspect of jig-making. Get it right and the process of using your jigs will be rewarding and it can save you hours of work in the future. However, even the slightest error can cause problems and render your jigs useless. Prepare well. Clear the workbench and make sure that you have the screws and fixings you’ll need, to hand. Avoid using random scraps of timber and take as much pride and trouble in making your jigs as you would in your turnings.

Turning the stool top

Place the stool-top blank on the bench, planed/sanded face uppermost, and mark a line across it which passes through its centre and runs as parallel as possible to the grain. Place the jig on top of the blank such that it is approximately centred on it and so that any one of its three holes lies directly over the pencil line, then use a steel rule to help centre the jig on the stool top; there should be approximately a 20mm gap all round. Carefully drill through the holes in the jig, into the stool top but deep enough only to accept the fixing screws that you will use, and then fix in place – if your jig is 25mm thick, use 40mm or 50mm screws.

Finally, mount the jig and the stool top on to the lathe, turn the edge and the top face of the timber, put a soft radius between the edge and each of the two faces then abrade to a finish. I usually apply sanding sealer while this is still on the lathe, thus the entire top surface, the edge and the first couple of centimetres of the underside will all be sealed. Unscrew the jig from the stool top and set the top to one side, taking care not to mark the finished surfaces.

Making the socket drilling jig

The very simple jig is designed to be used on the table of a pillar drill, but if you don’t have a pillar drill, fear not as I have also designed a means to adapt this jig for use on your lathe. The pillar drill ‘socket jig’ is very easy to make. It is simply a 330m-square piece of plywood, 12mm thick. Along two adjacent sides, mark a line 25mm in from the edge, giving an L shape, which you then cut off the board in one piece. You may notice that mine has a 70mm radius inside corner – this is not essential, but just makes it a little easier to cut out on the bandsaw.

Next, take the jig and draw a diagonal line across it, then use screws and glue to fix the L shape on top of the jig with the corner of the L shape on one end of the diagonal. Finally, mark a point on your diagonal pencil line, 60mm in from each side. This is where the centre of the leg sockets will be drilled. Your socket jig is now ready to use.

Drilling the leg sockets

Secure a 25mm Forstner bit in the chuck of the pillar drill and tilt its table such that it slopes downward, from right to left, to an angle of 12o°, and lock the table at that angle. Place the jig on to the table such that, when the drill is lowered, its spur lands on the jig’s diagonal pencil line, the pencil line points to the left and is at (approximately) 90° to a line which passes through the centre of the pillar and the centre of the Forstner drill. Clamp the jig on to the table and then adjust the table height so there is a gap of about 5mm between the drill and the surface of the jig, then lock the table at that height. This now ensures that the drill bit cannot burst through the upper face of the stool top.

Place the stool top into the corner of the socket jig, with its three screw holes uppermost, and lower the drill chuck. Manoeuvre the jig and the stool top until the drill tip locates into one of the screw holes, then clamp the jig on to the pillar drill table, with a final quick check to ensure that your previous settings have not changed. Drill the first leg socket, retract the drill, switch off and clean any shavings off the jig. Replace the stool top, rotate it through 120° and lower the drill, checking that the spur of the drill once again lines up with the screw hole. Switch on, drill the second hole and repeat the process for the third hole.

Adapting the socket drilling jig to fit on the lathe

For this purpose, you will need to make a carrier which is constructed to fit the dimensions of your lathe, so use my suggestion for the design, but impose your own dimensions upon it. This carrier is basically an L-shaped bracket comprising a base and an upright, which sits on the lathe bed. The underside of the base has a block which fits snugly between the bed-ways, screwed into place on it. The upright has a hinged panel, fixed with a simple flush hinge, which allows the panel to be tilted to an angle suited to stool legs. You will need to turn a socket to fit over the end of your tailstock quill (with the live centre removed) and then fix this socket to the back of the upright, at an appropriate height above the base.

All that is needed now is a mechanism which secures the hinged panel at an angle of 12° to the upright. I made mine from a piece of uPVC strip with a slot milled along its centreline and a screw hole at one end. The strip is screwed to the hinged panel and a thumb-screw passes through the slot, screwing into a hex nut which has been embedded in a little wooden block fixed to the back of the carrier’s upright. I cut a 12° wedge out of 40mm-thick stock and this slips between the hinged panel and the upright, giving me the exact angle every time, but also stiffening the hinged panel during the drilling process.

Drilling the leg socket son the lathe

Place a Jacobs chuck with a 25mm Forstner bit into the shaft taper on the headstock. Place the carrier on the lathe bed with the tailstock quill fully extended and located in the socket on the back of the carrier. Set the socket-drilling jig on to the carrier with its diagonal pencil line pointing upwards and with the corner of the L-shaped ledge at the bottom.

Rest the stool top on the socket jig with a screw hole at the bottom and slide the whole carrier forward. You will notice that the screw hole is somewhat lower than the centre of the drill, so slide the jig upwards until they meet up. Drill a couple of screw holes through the socket jig on its diagonal pencil line and screw the jig to the hinged panel, making sure the screws go into a central pencil line previously drawn on the hinged panel. It’s now ready for use.

With the lathe still switched off, slide the carrier and the socket jig forward until there is a gap of at least 5mm between the drill and the hinged panel. Lock the tailstock in place and wind the quill back in – do not unlock the tailstock until all three holes have been drilled. Place the stool top on the jig and advance the quill by winding the tailstock wheel. Make any minor rotations of the stool top so that the drill spur lines up with a screw hole. Clamp the stool top on to the carrier, switch on the lathe and continue winding the quill in as far as it will go. The drill will stop cutting when there is still the 5mm gap that you previously set, so retract the drill, switch off, unclamp the stool top, rotate it and carry on as before.

Production times

The couple of hours spent making these jigs will be repaid through the inevitable savings in production time. I’m not usually a spindle turner, nor am I a production turner, so these jigs have helped me to reduce stool production time quite considerably. I usually make them four or five at a time, from board to finished product in a half- day’s work. If you’re new to jig-making, hopefully you’ll see its benefits and think of ways in which you can make further jigs of your own design.

Making the rod for marking the legs

The purpose of this is to mark out the pertinent points along the length of the legs. Start with a piece of timber, 325mm x 20mm x 20mm and draw a pencil line along it, central to any long edge. Now fix a steel pin into one end of the rod, on its centreline, 25mm in from one end. I used a snapped-off 5mm drill bit for this. Next, measure the centres for the four panel pins and then drill four pilot holes about 0.5mm diameter smaller than that of the pins. Drive the pins halfway through and spot them with CA adhesive or epoxy before driving them home. Finally, mark the two pencil lines around two faces.

Marking out and turning the legs

Place a leg between centres and turn it to a straight taper 36mm at the tailstock end and 30mm at the headstock end. Place the toolrest parallel to the surface, about 10mm away from it and 10mm below centre height. Rest the rod on the toolrest with its pins pointing downwards, but not touching. With the lathe running, touch the steel pin up against the tailstock end of the leg and then gradually advance the rod and rotate it upwards by several degrees until the four pins leave scratch marks. Finally, use a pencil to register the rod’s two pencil marks on the leg.

Each leg is now turned in the usual manner and a scorch wire is used to highlight the two scratch lines at the top of the leg, and the one on each side of the bead. Finally, the tenon is cut on the top end of the leg by cutting a half-cove from the pencil line, and then a straight shaft at 25mm diameter from there to the end of the leg. Abrading and sealing are done in place and, if you’re waxing the leg on the lathe, wrap a little tape around the tenon so the wax doesn’t stray on to it.

Assembling the stools

One advantage of making your stool legs in this way is that they can removed from and returned to the lathe with ease. This allows each leg to be tested for a fit into its socket and a little gentle sanding can soon change an overly tight fit into a comfortable fit.

I recommend using a two-part epoxy adhesive as, with a well-fitted leg, cramping will not be necessary, but certainly would be with PVA adhesive. A slight chamfer on the end of the tenon will help adhesive to flow around the joint and a scratch-line or two around each tenon will help the adhesive to gather within the joint, rather than be forced out when the leg is pushed home.