Sunday, June 14, 2009

Why are sharp tools important?

It seems fairly obvious that sharp tools are necessary to be successful at woodturning, and very often a dull tool, or at least one that is not as sharp as it should be, is the reason for bad experiences. But have you ever considered why? I would like to suggest three reasons, though there may be others that I haven't identified yet.

  1. The most obvious is that a sharp tool will cut the wood cleaner. The wood fibers are more likely to be cleanly sliced by a keen edge than a dull one.
  2. A sharp edge can pick up a fine cut. A section through a sharp edge looks like two surfaces coming together at a fine point which is capable of removing fine shavings. When the tool becomes dull, that fine point becomes rounded off, and can only pick up a cut that is thicker than the rounded edge.
  3. A smaller force is needed to push a sharp tool through wood. There is an equal and opposite reaction, the rotating wood trying all the time to throw the tool backwards. A dull tool will see a larger backwards force, and will be harder to control.
Item three is perhaps the most important. A tool that is difficult to control may not cut in the direction you want it too, making it difficult to refine the shape of fine curves. If you have to push the tool forwards, you may just end up pushing it up and over the wood you are trying to cut. And if the wood succeeds in pushing the cutting edge backwards, the bevel may lift off the surface and a catch may result.

Tuesday, April 14, 2009

Nova Outrigger Hazard

I recently came close to having what could have been a serious accident with the outrigger on my Nova 3000. As I swung the swivel arm, it came crashing to the floor. Fortunately my feet were clear, and I was wearing safety shoes, but this hefty lump of metal could have caused some serious damage if it had landed on a foot.

What had happened is that over the years the threaded rod that holds it all together had slowly screwed its way up through the casting which is fixed to the lathe, leaving very little threaded into the lever underneath. So when I loosened the lever, then swung the toolrest around, the lever dropped off, with the toolrest assembly following suit.

In future I will be checking that threaded rod regularly to make sure it is not projecting out of the top of the casting. With hindsight this is pretty obvious.

Friday, January 09, 2009

Inspiration from nature

Satoshi Fujinuma is a Japanese lathe artist who took part in the International Turning Exchange 2008. In this video he talks about his work and how he finds inspiration from nature for the form, texture and colour of his works.

You can see more of his craft work, art work, exhibition and other works on his website.

Meanwhile, Philip Streeting has published a document full of examples of how design inspiration can be taken from examples in nature. (18Mb pdf)