Just recently, something came up that ‘got my goat’ and that was mention that a ‘flat back’ on a plane blade was good enough. Add in several “+1!” posts, and I couldn’t just leave it alone.
I mentioned that I don’t believe a ‘flat back’ = ‘sharp blade’ based on a ‘flat back’ being chock loaded with imperfections such as pits of corrosion, deep scratches and other nasties.
I got called on that, I suppose because I’m not ‘known to know anything’ and don’t write for any magazines, so what on earth would I know what I’m talking about. Right?
For your perusal;
If was can accept that this blade is generally flat, smooth and polished, then we’re in agreement. Obviously, I’m using a Pentax DSLR camera here…
The same blade, at the very edge under 200X magnification.
Note the deeper scratches on the right side, the small rust pits in the upper area, the relatively smooth and clean surface at the edge where there is a very small ‘back bevel’ put in place by use of a ruler on the stone, ala “the ruler trick”.
Chisels are a different problem altogether, and you pretty much have to accept the edge isn’t going to be ‘perfect’ but at the same time, a chisel isn’t usually as wide as a plane blade nor is ‘absolute sharp’ quite so important, unless of course you’re driving your plane through the wood with a hammer…