Instruction Example 5.5.: Stool

Conical holes are used for wood connection the tenons of which are prevented from slipping off by keying. This example is an exercise for the trainees to practise the manufacture of a simple stool with three legs keyed with their tenons in conical holes.

Material

One wooden disk (seat) and three round bars of hard wood.

Figure

Dimensions:

Designation	Pcs.	Thickness	Width	Length
		mm	mm	mm
Seat (disk)	1	30	350	350
Legs	3	40	40	450

All parts maybe in rough or finished condition.

Tools, measuring and testing means

Bit brace, spoon bit, dividers, straight edge, folding rule or measuring tape, bevel rule, pencil

Auxiliary accessories

Carpenter's bench or work bench

Necessary previous knowledge

Measuring and scribing, fundamentals of geometrical designs

Explanations to the working drawing

1 seat (disk) - scale 1:2.5,2 leg - scale 1:1
Ø = diameter

Sequence of operations	Comments
1. Prepare the working place.	Check the cutting edges of the spoon bit.
2. Clamp the seat.
3. Scribe the holes: - determine the centre, - draw the circular arc, - divide the circular arc into three thirds, - scribe the centres of the holes.	Dimensions are given in the drawing.
4. Select the auger bit and chuck it in the bit brace.	Select a bit diameter to suit the lower hole diameter, if available, otherwise use a smaller diameter.
5. Bore the holes.	Boring axis must correspond to the leg position. When practising for the first time, vertical position should be preferred.
6. Select the spoon bit and chuck it. Bit with handle need not be chucked.
7. Conically enlarge the existing holes.	Enlarge the holes up to the upper hole diameter.
8. Measure the enlarged holes.
9. Continue boring until the specified diameter is reached.
10. Check the results.

Stool