All of my garden has woken up, but none of the figs or pomegranates have shown even a budding leaf. I got so disheartened at this that I had to go and do something fun. So I went to work on the dagger to lift my spirits at least slightly.
I have decided to grind the bevel higher up to the spine, but not the same way along the whole blade – I ground less towards the tip so it remains strong. This has meant that the blade has a bit complex geometry which meant I could use hard belt most of the way, but I had to switch to slack belt for the tip. Luckily I have kept the option of half hard/half slack belt setup on my improved grinder.
I also ground the spine at approximately 45° angle to take off some weight. But again not all the way to the tip, so the tip is reinforced.
After I ground this basic shape It took me about an hour to get through four ceramics belts (60, 80, 100, 120) and the final was a zircon 120 grit where I stopped. This is actually a fairly difficult and delicate process and it is still possible (nay – easy) to mess up the lines and irreparably ruin the blade geometry, so easy does it. Because I am not too experienced with the belt grinder yet I had a few heart-stopping moments, but I managed to correct all the blunders in the end. From my previous works I know I have to be extremely careful up to approx 600 grit. After that messing up the lines in hand is not possible. But on my previous dagger I found out that on belt grinder that level moves up to 1000 grit, possibly 1200.
A lot of eyeballing was involved. After certain point I could no longer use the masking blue color and scribing tool, so to check whether my grind is symmetrical I used a folded piece of paper that I cut with shears to two aligning points. When I folded it around the blade I could see whether the lines are in the same position by putting the point on one side of the blade on the line and checking the point at the other side. After the final grind I scrubbed the blade lengthwise a bit with coarse abrasive pad to remove the quickly building rust and to scratch through the grind marks.
The future cutting edge is now approx 1 mm thick. Next step will be hardening the steel. For this I had to check whether this file was carbon steel throughout or case hardened. That I have done before polishing the whole shape by dabbing the spine and one side of the blade approx 5 cm from the tip with ferric chloride because in this area is preserved steel that was near the surface of the original file as well as steel that was deep inside. If the file was case hardened, the steel that was originally near surface should turn grey, while the steel that was deeper should be shinier. If the file is carbon steel throughout, it should all turn grey.
It has all turned monotone grey, so it is carbon steel throughout. That is good since it makes the hardening process easier. It is possible to make a cutting blade from case hardened file, but it requires to perform again case hardening, which takes more time and resources.
I hope the figs and pomegranates wake up -- better late than never! But I have to say, I worry for the walnut for the same reason: other things have waked, but it’s either taking its time, or not planning on waking up at all this year.