The business end of chisel blades usually have two angles – a ground angle of 25deg finished off with a honed angle of 30deg at the very tip. Like many people, one of the first things I learned to do with woodworking was to sharpen. While it may seem like a hassle to have to deal with messy lubricants, oil and water stones offer a very precise level of feedback. This is accomplished by scraping the blade against a harder surface such as a sharpening stone. As oil repels water they don’t work well together, and the oil that soaked into the stone will cause problems.
Tried various oils; 3-n-1, WD-40, Singer sewing machine, motor oil, cooking oils, etc, at first like various stone providers recommended but the stones would get clogged with metal particles that prevented the sharp edges I wanted and, cleaning the stones to remove the metal and oil was next to impossible. Needless to say I’ve never really thought too technically when it comes to sharpening grits and I’ll go to a strop when I need a finer edge.
For those who prefer a hollow bevel it is almost impossible if the surface of the stone is not absolutely flat. Your best value for 2-grit sharpening is with our Double-sided Diafold® hand-held sharpeners or DuoSharp® bench stone models. But change the angle of the knife, and slice across the fold, and the knife cut through like, well, a knife through paper. This may take up to 30 or 40 strokes, and is the indication that you should switch and start sharpening the other side.
I have also found that many cutting fluids are often too viscous to be used effectively for hand tool sharpening so we come back to the thinner fluids that are good for floating/cleaning. If you’ve already used oil it’s better to stick with it, or run the stone through a dish washing machine several times to hopefully remove the oil – getting the oil out is very difficult. As you repeat the process, a thin film of silty looking water should collect on top of the stone and on the blade.
The abrasives from the stone break away in a predictable manner giving the sharpener a clear indication of progress throughout the process. It’s perfectly possible to grind the primary bevel using the coarse side of the oilstone – that’s what you’d do if the chisel condition wasn’t too bad – but it’s much quicker and easier to use a bench grinder if you have one. Pull the blade over the stone several times until a burr is raised on the top side.
Well further to my comments about going over to the Paul Sellers (PS) method of sharpening I would like to add the following…… having recently ‘invested’ in one of his courses and seen first hand ‘up close and personal’ this method of using diamond plates, I am even more sold on his method of sharpening. Hollow grind on a stone no smaller than 200mm – any smaller makes the hollow too deep and reduces strength at the tip.