Tips and ideas for woodturningOn this page I collect tips for woodturning. I have another page with suggestions for what to turn.
If you have tips, that you think others should know of, you are welcome to send them to me. Then I will add them to my page - with your name as reference if you like.
You find tips on:
Freezing!, If the surface is torn, Avoid the tool 'running', The bowl gouge in a deep bowl, Use of the spur centre, Make flexible calipers, Turning balls, If the wood 'beats', Jam chucks, Centre of gravity for irregular objects
You can find more tips on: WoodCentral's Articles & Reviews.
Freezing!If you have to interrupt the turning of green wood for a longer period, you can put it in the freezer (or outdors in the winter) until you can continue the turning. Of course, you have to thaw it out before continuing the work, maybe in the micowave oven. By freezing, you avoid that the wood dries and you avoid that it goes mouldy. For storage for a longer period, put it in a plastic bag to avoid the slow drying that even takes place from frozen wood.
If the surface is tornIf the wood is porous, decayed or with short fibres, it is easily torn giving a bad surface. Then you can apply a coat of the surface finish (for example oil) that you intend to use. This will reduce the tearing of the surface. It will give some problems with clogging of the sanding paper, but the sanding will still be much easier than if you had to sand the torn surface. You may also choose to wet sand the surface with oil.
If the wood is very porous and decayed, you can apply super glue (Cyanoacrylate) to stabilise the wood.
Avoid the tool 'runs' when starting a cutWhen starting to turn from the surface and directly inwards with a gouge as when hollowing a bowl, it can be difficult to avoid that the tool 'runs' to the side leaving a bad spiralling groove in the wood. If you are skilled, you can control the tool to avoid this but others may take advantage of some tricks. One solution is to turn the tool so that you start using it as a scraper and then turn it to cut as soon as the cut has begun. A better solution may be to hold the cutting part of the cuttiing edge vertical and support the tool firmly with the thumb on it's left side on the toolrest to prevent it from 'running'. Here, you have to be sure that the cutting edge is tilted slightly towards the thumb to ensure that the tool won't run in the opposite direction.
Another solution is to use the tip of a skew to make the initial cut and then change to the gouge.
The bowl gouge in a deep bowlWhen for example turning a deep bowl or a bowl with a sharp 'corner' in the bottom, at some point the bevel of the bowl gouge can't keep in contact with the wood, and the tool becomes difficult to control.
One solution is to use the rim of the bowl to support the gouge and turn the flute of the gouge more upwards. Another solution is to use a gouge with a larger grinding angle. Or you can use a bowl gouge with another type of grind, 'fingernail/swept-back grind' or (better in my opinion) 'Irish grind'. A special hook tool or a ring tool may also be used. If nothing else is possible you may try a scraper.
A similar problem arises when turning the side of deep shallow holes or hollowings. At some point, the bevel can't keep the contact with the wood because the tool hits the oppositte rim of the bowl. You can get a little deeper with a bowl gouge with a smaller grinding angle but the same special tools as mentioned above for turning the bottom of bowls are better. In addition, Melvyn Firmager has developed two very special grinds: the 'Nib gouge' that can actually bore holes directly into the wood and the 'swept-back gouge' that can turn almost in line with the tool.
Use of the spur centreSome spur centres have a rather broad cone in the centre, which can prevent the centre from getting into the wood so that the spurs can't get a good grip. A solution is to grind the cone so that it is shallower but it is difficult. A simpler solution is to drill a hole in the wood for the cone.
In wood with an irregular surface that for some reason can't be made flat, it may be difficult to get a good grip with a centre with four spurs. You can then try using a centre with three or two spurs.
Especially the centre with two spurs but also those with three and four can have a tendency to split the wood. That problem may be reduced by turning the spurs so they are aligned diagonally to the grain. Even better is it to pre-drill holes for cone and spurs.
Make flexible calipersCalipers are good for measuring the thickness of the walls of a turned object. If you are working with hollow forms you need several different calipers to be able to measure all possible shapes, and they are expensive and takes up space.
A simple and cheap solution is to make your own flexible calipers. It can be made from two heavy copper wires (e.g. from a high power installation cable). On the middle of each wire is soldered a small copper or brass plate. The two plates are screwed or riveted together through a hole in the middle with the wires on the outer sides. The resulting double callipers can be bent to suit the purpose. When you bend the wires, ensure there is the same distance from the rivet to each wire end and that when closing the callipers the wire pairs touch each other at the same. In this way you can measure the wall thichkness by measyring by the distance between the two ends oppostite to the two ends that are not used on the wall. Instead of soldering, the wires can be held by pressure from the two plates, if the plates and wires are bent (cut) to keep the wires in position. Then, plates of wood, aluminium or iron can be used. Alternatively, the wires can be glued on the plates.
Brian Clifford has a description of another type of tool for thickness meaasurement that you can make yourself. This one may also be made from pliable wire so that it can be adjusted to fit the project.
Turning ballsThere are many ways to turn balls. Usually, you start by mounting a square blank between centres or in one end in a scroll chuck. The blank is turned to a cylinder and the diameter of the cylinder is marked to give the 'ends' of the ball. The ball is shaped as good as possible. Using a template can help. The ball is parted off. It will be perfectly round around the lathe axis but rarely in the other direction.
You now have to rotate the ball 90° from the turned axis and re-mount it in the lathe to turn it spherical. Most turners rotate and turn the ball several times to ensure that it is perfectly spherical. Finally the ball is sanded but not too much as sanding may makes it oval.
The problem is how to re-mount the ball. There are more ways to do it. A simple solution is to make a jam chuck. Another solution I've found somewhere on the internet:
You make to wooden chucks, both with a recess for holding the ball. One chuck is mounted in the scroll chuck, on the spindle thread, or in the morse taper. The other is made to fit on/in a live centre. The cone can be removed on some live centres and then the chuck can be made to fit where the cone was. In the illustration above there are added two rubber rings/o-rings to reduce the risk that the chuck creates marks on the ball. These rubber rings can be omitted, which is actually an advatage as they make centering of the ball more difficult. Without rubber rings the chuck can be made from a soft type of wood like lime. Without rings the chuck can also be made smaller giving better access to turn the ball.
If the wood 'beats'The wood often 'beats'/'casts'(?) when it is remounted after having been taken off the lathe. If the reason is that it's base isn't true, you may add a piece of adhesive tape on the end facing the spindle in the position where it casts furthest out. This usually doesn't help if the wood has changed shape due to changing moisture content.
Jam chucksJam chucks are fantastic because they can be made to fit the object perfectly, also for odd-shaped objects. They are best made from a soft type of wood, softer than the wood the object is made from. Unlike what you usually want, it is best to turn to a rough surface that will grip better. This can be achieved from scraping.
It always helps to add a little moisture to the chuck before mounting, as it gives a better grip. Of course, you can't always allow that the turned object gets into contact with this moisture.
If the chuck doesn't hold well enough and you want to avoid making a new, you can try putting a piece of kitchen roll paper (or the like) beetween chuck and the turned object.
For larger objects or if the grip isn't optimal or you want to be safe, the tailstock live centre can be used to press the mounted object against the jam chuck. You can place a small piece of wood between the centre and the object to avoid making marks.
Centre of gravity for irregular objectsIf you know the centre of gravity of a piece of wood, you can choose the correct position for mounting for the best stability. A way to find the centre of gravity is to tie a string around the wood and let it hang in it. Then, the centre of gravity will be right under the string. To find the centrre of gravity for the face that is going to be used for mounting the wood, you draw a vertical line on the surface in line with the string. Then, the string is moved to another position and a new line is drawn. By repeating this some times, the crossing point of the lines will be a good estimate for the centre of gravity.