As part of my project to build a holder for my router planes by hand I found myself in a position where I needed to plane some end grain. When doing that my normal go to is my low angle jack plane. I’ve used it with great success in the past on larger pieces but this time I thought I’d try building a little shooting board to use it with. So I built a tiny shooting board out of some scrap wood and set to work. At first it seemed to be working OK, but after a couple of passes I wasnt really getting shavings but rather dust. I watched videos, I read, I went to Reddit and asked people, I did all the things. I’ve come to the consensus that my blade just wasn’t sharp enough. So I went to sharpen it again and realized at one point I had made the primary bevel at 30 degrees. Having issues with the shooting board I figured I would try re-beveling it to 25 degrees. Before I started doing that I went to flatten the back and I noticed that I wasnt getting a consistent polish on the back of the blade with my 300 grit diamond stone. To make sure I wasn’t I put some marker on the back and tried polishing it again…
So it looked to me like I had a bit of a convex hump in the middle of the back of the blade. Then I started thinking that if I had a hump in the back of the iron, and I was trying to flatten just the front part of the back of the blade, that it would be possible that I was rocking the iron following the hump while flattening.
Wanting to make sure that I had a totally flat back I decided to polish the entire back in the other direction – that is – from front to back. I took a piece of granite and started with 100 grit sandpaper and worked my way up to 600 (not pictured (also 220 was already on another piece of granite so not pictured here)).
It took some time – but I could tell I was making progress on the lower grits…
You can see above that I had low spots toward the middle of the blade as well as at the edge of the blade. I thought I had figured out what my problem was! The back of the iron along the blade wasn’t getting flattened correctly! I kept at it…
More progress! Almost there!
Still a couple of horizontal scratches in the middle of the blade, but the forward edge looks great. So I moved through the other grits all the way up to 600. Feeling like I had it all sorted out I went over to my diamond stone and started polishing the blade on the 1000 grit stone. Now, my diamond plates arent long enough to polish the same way so I hold the blade sideways and only polish the forward part of the blade. I couldn’t believe it but I saw this…
Somehow Im hitting high in the middle again! So Im at a little bit of a loss. Disappointed for sure. I can’t quite sort out how this happened. I even backed down to my 300 grit diamond stone and saw the same thing. I’m going to have to sort out what Im doing wrong here. I can feel a wire edge as I move through the grits which is sort of my indicator that Im doing things right – but why can’t I get a consistent polish on the back?!?!?