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I got this 150 mm Tsunehisa petty in SK steel for $35. I forced a patina on it and put a decent edge on it. But, it's pretty boring to use. I assume I just need to thin it? I'm pretty sure it's a full flat grind.
I have a 150/400 DMD diamond stone, SG 500, SG 2000 and the JKI 6000s. I assume I want to start at 150 grit and work all the way up to 2000? And I basically need to lay the secondary bevel flat on the stone then lift the spine slightly off of the stone and go to town on it?
I finished thinning this thing last night. I haven't got a chance to use it yet. The choil shot looks pretty good I think. What do you think?
I was pretty nervous to do this. It was my first time thinning. For some reason in my head I thought I would end up losing a lot of height on the knife as I thinned it due to the full flat grind. But, I didn't lose any. I did watch the primary bevel shrink from more than 1 mm to maybe .1 or .2 mm. And I did attempt to lift the heel ever so slightly so I was primarily removing material closer to the edge. This worked and I ended up with a convex grind. The 5 mm closest to the heel did not lose any material. I think I only worked on this for an hour and a half total. It's not a very large blade and the SK steel maybe easy to work with. But, also the 150 grit diamond stone really removed a lot of material fast. It's scratches were easy to remove going through the grits. But, there were some scratches higher up the blade, close to the heel, that weren't coming out. I'm not exactly sure how those scratches got there using the 150 grit but weren't easily reachable once I moved up to 400 grit. But, now I know for the future that when I thin a knife I'm going to end up with some deeper scratches on the hira. Or is there some way to get access to these? Like using a soft sanding sponge or some powdered compound?
The after pic is on the left obviously.
I start with 220 grit sandpaper on a little homemade sanding block. Others go higher, I finish at 400
I start with 220 grit sandpaper on a little homemade sanding block. Others go higher, I finish at 400
View attachment 307472
That makes sense. The felt pad helps fill in the low spots on the blade, but the block prevents you from making new low spots.
