Turning Your First Bowl
Tuesday 10 May 2011
Are you looking for some expert tips on turning your first bowl? If so, then look no further than this article by Michael O Donnell which tells you all you need to know
Woodturning has moved on a long way since I first started in 1973. My first experience was during an evening class, but at that time blanks weren't available. The first piece of wood I bought was a square of iroko (Milicia excelsa) - 230 x 230 x 75mm (9 x 9 x 3in).
However, we now have an infinitely better selection of wood, a great selection of chucking techniques and tools, and a greater awareness of grain patterns and design. All of this puts you in control of the whole process.
If you are new to woodturning then the chances are that your first project will be a bowl, and there is an even greater chance this will be made from a bought blank. So making your first bowl is a good place to start putting in good practice.
Choosing a blank
Bowl blanks are 'cross grain' blanks, which means that the grain runs across the face of the blank and therefore the blank sat vertically in the tree.
I would say the ideal size is something like that of my first bowl, 230mm (9in) diameter x 75mm (3in) thick - cross grain. Any bigger adds difficulty; any smaller and it won't have the prestige you are looking for.
I would advise you not to spend a lot of money on timber as you are bound to improve later. In fact, you are probably better off buying two or three inexpensive blanks so that you are not too worried about making a mistake.
There is such a variety of timber available; ask for advice on something that will cut and finish easily - the wood store should be able to advise you on this. A good place to start is with timber local to where you live.
Blanks are normally kiln dried so that movement of the finished piece is minimal. Air dried timber will have a greater moisture content and will move more after turning and drying. The kiln dried blanks should be sealed to maintain their moisture level. Green blanks should be avoided at this stage, as the risk of failure is high, and, if you plan to turn green wood then you should be starting with a log as opposed to a blank.
Looking through the pile of blanks available, when you pick one up, the first thing to do is to look for splits or cracks. If you find any then you should discard them - there is no point in starting with unnecessary problems.
Colour is the first thing that you might find attractive, anything from the creamy white of sycamore (Acer pseudoplatanus), through rich browns to the contrasting red heartwood and creamy sapwood of yew (Taxus baccata). The choice is very wide and the selection is a personal one. Though whichever colour you choose, it is the variations created by the grain pattern that will bring it to life.
Don't forget that these homogenised blanks come from trees,
and relating them to where in the tree they come from will help you judge what grain pattern will emerge in your bowl.
Logs would first be cut through-and-through to make slabs, or planks. The slabs are then dried to stabilise them and then the blanks are cut from the slabs. The difference in grain pattern in the finished bowl can be dramatically different depending on which part of the tree it comes from, and which way up in the blank the bowl is orientated.
To decide which part it comes from, you first need to look on the face of the blank then look on the end, in line with the grain, and check the grain pattern of the timber. What you will be looking at is grain which forms part of a circle, or near enough, as very few trees are exactly round.
I have drawn some of the most typical patterns that you are likely to see on a blank and from there the different grain patterns, depending on which way up the bowl is in the blank. Now when you look at a bowl blank, you will have an idea as to what grain patterns are possible, which will help when you are designing your bowls.
Some of the blanks from trees with contrasting heart and sapwoods will have patches of the sapwood. These can be used to great effect and look good if they are balanced. When they are not balanced, however, they can be distracting. Therefore, it is advisable to position your bowl to give the effect you want.
Having chosen your blank, the last thing you need to decide on is which end will be the top. When that is decided, write 'top' on the chosen end so that next time you pick it up you will know exactly where you are.
The simplest shapes often work best; they emphasise the beauty of the wood, and they can be very functional and feel nice in the hand. For example, a curve running right through from rim to rim that the eye can follow, or a foot that lifts the form and gives it elegance - say about 10mm (3/8in) high.
As a rough guide, make the base about one-third the bowl diameter - in this case 75mm (3in) diameter. For a first bowl, I would go for something chunky - say about 20-25mm (3/4-1in) - which will give it some weight.
It is also a good idea to gently chamfer the rim, keeping the edges sharp for definition. Also, a slight under cut at the rim will give a very nice feel to the bowl. This design is not only good visually, but it is also a straightforward one to turn and you can be sure of a good first bowl if you follow this method.
As this is your first bowl then I have made the assumption that you have a lathe with faceplates, a set of turning tools, but probably no chucks. There are a number of procedures that can be used in this instance.
1. Fit the base of the blank on a 75mm (3in) faceplate and turn the whole bowl in one operation
2. Fit the faceplate on the top while the outside is turned then fit the faceplate on the foot and turn the inside.
Procedures 1 and 2 do leave screw marks on the base of the bowl, these are not desirable but I think they are preferable to the recess left by expanding chucks.
3. Glue a waste block on the base and follow either of the opposite procedures, which will avoid leaving screw holes in the base.
1. Centre the faceplate on the base of the blank and fix it with four 20mm (3/4in) screws, with the weight of the screw protruding 12mm (1/2in) through the faceplate
2. Set the lathe speed to around 1200rpm
3. Mount the blank on the lathe
4. Position the toolrest 12mm (1/2in) away from the wood
Alternative chucking procedures
The advantage of this procedure is that with the first holding on the top of the blank, the outside can be turned from the base to the rim, which is with the grain. Also, there is more room to make the foot.
When it comes to fixing the faceplate to the foot, the positioning has to be precise. One way to achieve this is to turn a groove under the foot at the same pitch circle diameter as the screw holes and be sure all the screws fit into it. This also helps to disguise the screw holes. Adding a couple of smaller grooves gives a decorative base.
1. Cut a waste block about 90mm (3 1/2in) diameter - a little bigger than the foot and faceplate - flat on both surfaces and with an even thickness
2. To glue a waste block on to the blank, apply a PVA glue to both the blank and the waste block
3. Take a piece of newsprint and place it over the glue on the plank
4. Place the waste block on top and centrally over the blank
5. Apply pressure and leave 12 hours for the glue to set
6. The turning procedure is then exactly the same as procedure 1, but this time there is more room to make the foot as the excess waste block can be turned away
7. Sand off the glue and newsprint and oil as before.
1. The outside is turned while the blank is held on the top, as per procedure 2
2. Glue a waste block on the foot as per procedure 3a; pressure can be applied from the tailstock
3. Once the glue has set, turn a recess 3-6mm (1/8 â€“ 1/4in) deep in the waste block just to take the faceplate and centre it
4. You can now follow the remainder of procedure 1
5. The gluing procedure could be speeded up by using hot melt glue, though I have to admit that it is one I haven't tried.
Procedure 1: Turning the outside
5. Take a 12mm (1/2in) deep fluted gouge and start shaping the outside of the bowl, following the bowl shape from the first cut
6. Now making these cuts from the large diameter to the small on a cross grain blank is against the grain, so there is an expectation that the surface produced will not be as good
as working with the grain. Though, with the right kind of wood selected and keeping the tool sharp, a good finish can be achieved
7. These cuts will be far easier if you hold the handle of the tool in your left hand. Being able to turn with either hand will help you develop your turning quickly
8. Keep the cuts small, around 3mm (1/8in) deep to make an easier cut. Leave some wood on the foot for finishing later. When there are only two or three cuts left, you need to re-sharpen the gouge
9. If you have room between the base of the bowl and the headstock of the lathe, then make the foot with a few small cuts
10. To refine the shape of the bowl, take a 25-38mm (1-1 1/2in) skewed scraper with a long cutting edge and slide it backwards and forwards over the surface to refine the shape you are trying to achieve. Work the high spots first then the whole surface of the piece. Take very light cuts and re-sharpen the scraper every few minutes
Procedure 1: turning the rim/inside
Put a pencil line to show the width of the rim then shape it with the deep fluted gouge, working from the small diameter to the large, which is with the grain. The last cut should just remove the pencil line.
11. Replace the pencil line to mark the width of the rim
12. Start turning the inside from the centre making each cut the finished shape so that the final cut comes automatically
13. Working from the large diameter to the small on the inside of a cross grain bowl is working with the grain. Sharpen the tool before starting the inside and again, two or three cuts
before the last one
14. Check the 'evenness' of the wall thickness as the turning proceeds using the finger and thumb as callipers and make adjustments
15. Refine the inside shape with a large left-hand curved scraper, sliding it backwards and forwards over the surface to refine the shape of the bowl
16. Work the high spots first then the whole surface. Take very light cuts and re-sharpen the scraper every few minutes
17. Switch on your dust extractor and wear a face mask
18. Start with a 100 grit abrasive, and on the inside wrap the abrasive around a piece of cloth or a handful of shavings - this will further refine the shape and produce an even surface finish
19. Work through 150 and 240 grits for a fine finish
Finishing your bowl
Using an oil finish will bring out the colour and grain of the wood at the same time as giving it a tactile surface. Apply with a brush while running at a very low speed - or turn the bowl by hand - to get an even coverage. Allow a few minutes for the oil to soak in then wipe off the surplus. Bring the lathe back up to turning speed and burnish the surface with a clean cloth. Repeat as necessary to get an even surface. Follow the manufacturers instructions if different from above.
Finally, remove the bowl from the lathe and the faceplate from the bowl. Tidy up any loose grain around the screw holes - plugging them would be a good idea at this point. Write your name on the bottom of the bowl, and the date you made it. Lastly, apply oil to the bowl's bottom. You can now stand back and admire, but don't ever think of giving it away or selling it.
Also, a big thank you goes to Mick Barnett and Fred Houghton for supplying the timber for this article.