Chris Knight
Established Member
I have finally started on carving practice - having finished chairs, a box for the carving tools and a carving super bench (where super = above, ie it sits on my regular bench! - to bring the carving surface to somewhere that does not kill my back) I have no more excuses and have started serious practice.
I have been quickly reminded of the lessons I learnt with Chris Pye on the sharpening of carving tools (for any carver, those lessons alone would be worth the price of the course!) and wondering what, if anything, could be applied to regular woodworking.
I offer the following observations:-
1. When sharpening a chisel, say, you should not be able to see the edge under a strong light and with magnification (I use an Anglepoise type lamp and an Optivisor magnifier ( http://xtronics.com/optivisor.htm ) to look at the edge. If you can see any, I repeat ANY light reflected from the edge it is not sharp.
2. If, running your finger or nail over the edge you can feel ANY roughness, it is not sharp.
3. Don't waste your arm hair, it is no test at all, you can cut that stuff with a lawnmower. Instead, cut a hard piece of wood a few times and repeat tests 1 and 2. This has the benefit of "consolidating" the edge and may well reveal weaknesses once tested as described above but will also strengthen the edge. Simply sharpen it again but taking off the minimum of metal.
4. When you think the edge is really sharp, cut a piece of wood like Lime (the carver's favourite) or Jelutong - a good second best, or Walnut at about 45 degrees across the grain and observe the result. If you see ANY scratching within the cut area, your blade is not sharp.
5. Do NOT rely on stropping to sharpen an edge that is revealed as less than perfect by the tests above - it won't work, you will simply round over the edge. Stropping- do this by hand- will make an edge that passes these tests into a gift from the gods.
I tested eight of my woodworking chisels with this method and whilst I could not see the edge of any of them( for 95% of the edge, slight slivers of light on the rest), only one passed the scratch test. I resharpened all so that they too passed and it made a world of difference to their paring ability.
I have been quickly reminded of the lessons I learnt with Chris Pye on the sharpening of carving tools (for any carver, those lessons alone would be worth the price of the course!) and wondering what, if anything, could be applied to regular woodworking.
I offer the following observations:-
1. When sharpening a chisel, say, you should not be able to see the edge under a strong light and with magnification (I use an Anglepoise type lamp and an Optivisor magnifier ( http://xtronics.com/optivisor.htm ) to look at the edge. If you can see any, I repeat ANY light reflected from the edge it is not sharp.
2. If, running your finger or nail over the edge you can feel ANY roughness, it is not sharp.
3. Don't waste your arm hair, it is no test at all, you can cut that stuff with a lawnmower. Instead, cut a hard piece of wood a few times and repeat tests 1 and 2. This has the benefit of "consolidating" the edge and may well reveal weaknesses once tested as described above but will also strengthen the edge. Simply sharpen it again but taking off the minimum of metal.
4. When you think the edge is really sharp, cut a piece of wood like Lime (the carver's favourite) or Jelutong - a good second best, or Walnut at about 45 degrees across the grain and observe the result. If you see ANY scratching within the cut area, your blade is not sharp.
5. Do NOT rely on stropping to sharpen an edge that is revealed as less than perfect by the tests above - it won't work, you will simply round over the edge. Stropping- do this by hand- will make an edge that passes these tests into a gift from the gods.
I tested eight of my woodworking chisels with this method and whilst I could not see the edge of any of them( for 95% of the edge, slight slivers of light on the rest), only one passed the scratch test. I resharpened all so that they too passed and it made a world of difference to their paring ability.