I took a break today from the Japanese box to shower some TLC on my Japanese chisels. Three of the larger ones had never had their backs flattened properly. Mainly because it was way too tedious, but also because I rarely use the larger sizes.
After some token flattening on my new coarse diamond stone, I realized that the leading edge of the bottom on these chisels was curved up to such an extent that what was needed was to tap the front of the chisels with a hammer. I gather this is a fairly common set up activity among Japanese chisel owners.
I won't get into the details of the operation, a google search will yield plenty of information. My own observations are that is should be called 'bashing out' rather than tapping out as it takes way more force to get the steel to move than tapping would provide. I wound up using a carpenter's hammer on a piece of railway track to get one to move! Further, a caution that the leading edge will chip if you are careless and hit it directly.
Anyways, now my Japanese chisels are all flat and sharp and ready to go! That only took all day.
3 hours ago