One thing that bowl turners quickly learn is the high cost of bowl blanks and the limits on available sizes. While the answer is also quickly learne, namely cutting one’s own blanks, the question remains as to how to do so. That answer is generally found int he use of a chainsaw and in making a couple of cuts, one of which is seldom done except by woodturners.
Before using a chainsaw it is important to get instruction from a long time user. In some area there are instructors in the use of a chainsaw and these can be sought out. While the saw is used day in and day out by lumbermen and firewood cutters, the chainsaw is admittedly one of the most dangerous of tools and safe use lies in the hands of the user.
One of the rules of safety for a chainsaw is not to cut wood in the pile or on the ground. A holder or sawbuck is needed. For the purposes of cutting a bowl blank we assume that a log has been placed in a sawbuck and the chainsaw is ready for use by an experienced cutter.
Most logs will have some splitting at the end even is very recently cut. Therefore a cut is made taking off the first four inches of the log. This will likely clear the splits but if any are still seen then another few inches may be cut off. Once the end is clear measure the diameter of the log. For illustration purposes let us say that the largest diameter is twelve inches. Measure back on the log the length of the diameter, in this case twelve inches. Now cut this section off.
This leaves a short log of twelve inches length and diameter. All cuts to this point have been the common crosscut for which a chainsaw is designed. The short log will become two bowl blanks and for this will need to be ripped down the centre, a cut for which the chainsaw is not designed. To see the reason for the cut look at the end of the log. It is a rough circle as few trees are perfectly round. A bowl in profile is a semicircle so the log needs to be ripped.
People who use chainsaws to rip logs into boards use special chains. This is not necessary for woodturning purposes. The trick is to hold the wood in sawbuck that gives access to the end of the short log while supporting it well and to hold the saw at a sixty degree angle as it cuts. This allows the long shavings to clear as the cut is performed. Allow the saw to do the work. Forcing it puts undue pressure on the motor. Once the saw cuts through the log, two blanks are formed and ready for the lathe. They may be laid back in the sawbuck and the corners cleaned for easier turning or they may be rounded on the bandsaw but they ready for use.
Neither cut is difficult and a supply of logs from a firewood supplier or the local landfill can deliver a lot of bowl blanks that quickly pay for the saw. Added to this is the enjoyment of green wood turning and the satisfaction of cutting your own bowl blanks for turning.