I started the evening off by putting about a dozen plane irons in my electrolysis tank for rust removal. They need to sit in there for a while, we will get back to them later.
Initial Grinding Wheel Fixture Testing
Onto setting up the new grinding wheel mount fixture from Lee Valley. For the evening I am just going to clamp it to the bench and move the grinder in behind it. At some point I will cut a board to mount them both to and make it a bit more stable. I roughly set the angle with the new angle gage, I really should read the instructions fully. I dug through the pile of chisels that need to be sharpened and found one that I was willing to experiment with. I scribed a line with a square across the tip as it was far from being square. I flipped on the grinder, let it wind up to full speed and ground the tip square and flat, it doesn’t take much. I flipped off the grinder to set the chisel in the fixture, this only took seconds. Next to set the depth, grinding wheel still spinning down, makes it challenging but I managed to get it done well before the grinder stopped fully. Turned it back on, let it spin up again and proceeded to grind slowly on the chisel. My fingers are about an inch and a half from the tip, I pull the fixture out of the jig and check the temperature. Once it starts getting uncomfortable to hold due to heat I hold it flat on my drill press base or table. The large surface area removes the heat from the chisel very quickly, and I do this several times over the course of grinding so that I don’t overheat the metal and loose the temper. This seems to work reasonably well, although I will have to tweak the angle of the fixture and I really should read the instructions before doing any of the good chisels. I also need to get a diamond dresser so that I can flatten the grinding wheel and true it up. There are a couple of high spots on the wheel, so that goes on the shopping list. I also need to cut a board to mount the grinder and the fixture to to make things a bit more stable, as I don’t want to have the angle change part way through the process accidentally. The fixture worked well!
Chisel and Iron Back Flattening
I checked the electrolysis tank, and they could be in there a bit longer so onto some chisel and iron back flattening. Look in the bin for chisels and sigh heavily as there is at least of dozen of them that need the backs flattened. I have been putting this step off until I received the 240 grit stone, well its here and time to get flat, err get them flattened. I start out by flattening the stone as I didn’t check or do that on my first use. Some take only a couple of passes, some take a couple dozen, some take considerably more. For the evening I am only doing the first step as I have a lot to do. Every couple of backs I reach for the flattening stone and give it a few passes over the water stone to keep it true. I also spray on water as needed which is at least once per chisel and those that take more passes get a couple extra spurts. Most get done quickly, but a few take about 5 minutes.
Some people take quite a bit of time in doing this process, I am of the mind that only the last quarter inch or so really needs to be “that flat”. I don’t mind if the upper part isn’t completely flat, even a bit of pitting on an older iron. I am careful not to create much of bevel on the back, I try to keep it all on the same plane. The theory on this is, as long as you have two planes meeting at a point approximately at the angle you wanted it doesn’t matter how long that plane is, assuming its not not extremely narrow. I’m also of the thought that the angle just needs to be close, off by 1-3 degrees is acceptable, off by 4-5 degrees starts changing the cutting geometry enough to matter. So the difference between 25 and 27 degrees is negligible, but the difference between 25 and 30 may affect your cuts.
Back to the irons that were in the electrolysis tank, after about 2 hours I removed them. I took a not so terribly sharp chisel and removed the thick black buildup from the process. I then took a scrubby and worked on the remaining black buildup, I tend not to get it all, but I do manage to get rid of the rust. After rinsing and drying them I start flattening the backs. There are a couple of the larger ones that are pitted fairly deeply, they may have to go to the power sander to remove more material as my patience are getting a bit thin at this late hour. I did manage to get all but 2 of them through the 240 grit stone. I will save the progression to finer stones for another evening or two.