In terms of price, the water grindstone and wet grinder could hardly be further apart. While you can get cheap sharpening stones for less than 20 euros, the wet sharpening machine with diamond sharpening stone cuts a hole in your wallet for more than 600 euros. But do you notice that in the result? There’s also a DIY trick in the video to put the proverbial finishing touch on chisels with an old belt.
transcript of the video
(Note: This is bonus content for people who cannot or do not want to watch the video above. The video track information is not reflected in the transcript.)
In this video I test who can actually grind sharper: the human with a classic water grindstone or the sharpening machine with a diamond grindstone.
Anyone who works with wood typically uses a chisel somewhere at some point. Yes, and those who use chisels blunt chisels. Even when you buy new chisels, they’re sharpened at the right angle, but they’re not really sharp. That means you definitely need to sharpen tools. But now the question is, with what? There are the craziest contraptions and machines out there to sharpen things. In this video I would like to try two very typical ones. On the one hand we have the classic water sharpening stone, which is placed in water for a while and then you just have to push the chisel back and forth at the right angle. Yes, and then it’s supposed to be sharp again.
In this video I compare a wet sharpening machine to a diamond sharpening stone, which is pretty much the most expensive way to sharpen a chisel. One should therefore expect that this will also be correspondingly sharper. For this comparison, I got myself two identical, inexpensive chisels, they are brand new, and I’m going to sharpen them with the whetstone and the one with the machine. On a chisel, the bevel is typically at a 25-degree angle to the back, and you should try to stay within that 25-degree angle whenever possible. If you sharpen the chisel, it quickly becomes blunt again. If you make the angle more obtuse, well, the word says it all: you can’t get it really sharp and it’s just very difficult to push through the wood.
In order to be able to maintain this angle on a normal water grindstone, we need a small device that you can either buy ready-made or build yourself. Yes, and that’s exactly what I’m going to do now. This is super quick to assemble and not at all complicated. You just need two multiplex boards of the same size and one is notched so that it can be placed on the whetstone at an angle of about 25 degrees. Then four holes are drilled in the corners and I make the arches in one board a little smaller than the other board so that the screws can later be distributed in the lower board.
So we need the boards, two castors, four long screws and matching nuts and washers. Yes, and now we can screw the whole thing together. The rollers are simply screwed to the two boards from below with the long screws, and you can now clamp the chisel between these two boards. The holes in the lower board are a bit smaller so that the screws don’t spin, and then the whole thing can be easily locked at the top with the wing nuts. Then I have to align the whole thing, of course, and then I can simply write down the amount that the chisel protrudes from my jig at the front. Then the next time I want to adjust that, it’ll be a little easier for me because that measurement for 25 degrees is always the same.
Now we can start grinding. My sharpening stone has two sides: a thousand grit and a 6000 grit. And before using it, you should put it in the water for about half an hour. The edge on these cheap chisels was not sharpened at right angles to the side of the chisel. That means I have to fix that first. Yes, and I actually had a bit of a hard time there. I’ve readjusted it a few times, but the whole thing didn’t really turn out right-angled for me either. Then you can take the chisel out of the jig, turn it around and regrind the mirror side. This will also remove the burr created by grinding the bevel on the mirror side. It took me about 20 minutes in total, but that was also due to my fumbling around with the right angle. But with a little more practice and patience you can get it right-angled.
Then a first cutting test. It’s just spruce wood now, and the chisel slides through it without any problems. Again with oak, of course it’s a bit more difficult because it’s much harder than spruce, but you can work with that too. Then we can start the grinder now. This is a Tormek T4 with a diamond wheel and this diamond wheel has the great advantage that it doesn’t wear out and shrink over time. Of course, I also have to set this so that I grind the chisel at exactly 25 degrees. And grinding machines of this type actually always have the same construction: It is a metal rod on which you can attach the appropriate holders for different types of tools. This is now a very simple holder for a chisel. Yes, and when I put it in there, the cutting edge is really sharpened at a 90-degree angle. The diamond grinding wheel removed quite a lot, and after just three or four minutes I was completely through with the grinding.
I can also grind the mirror side with the grinding machine. To do this, I simply hold the chisel to the side of the grinding wheel and when I use it now, I have to honestly say that I don’t really notice any difference to the hand-ground chisel. But now this grinder has another feature and that is a leather honing wheel. This allows you to polish the cutting edge and the mirror side again. A special polishing paste is applied to the leather wheel for this purpose, and then you simply hold it on there freehand. Yes, and if you now take a close look at the cutting edge, it is really smooth as glass, and I also used it to polish the back again. When I cut through the wood now, I notice a huge difference. It goes much easier through the wood than with a chisel sharpened only on a diamond wheel or even than with one sharpened on a water stone.
Now, of course, I ask myself the question: Can I polish the edge of my chisel that was sharpened with a water stone? Let’s try this. Here I simply have a piece of leather left over from a project. Because you’re supposed to rub some oil on the grinding machines at the beginning, I simply take Ballistol and then use the same grinding paste as for the grinding machine. I used this to grease the piece of leather and then I just pull the chisel manually over and over the piece of leather at about the right angle. I do that for about 5 minutes. Yes, and lo and behold, when I go through the wood with the chisel, I hardly notice any difference to the grinding machine, which costs more than 600€. I can tell which chisel is which by the differently smooth mirror edges of the cutting edge, but when carving I really only notice a minimal difference in favor of the chisel that was sharpened on the grinding machine.
There are still a few advantages to using a grinder. First, sharpening the chisel is much quicker than using a waterstone. Second, it’s much, much easier to get that 90 degree angle really neat and clean. The third big advantage of such a grinding machine is that I can also grind completely different things with it, for example those turning tools that have a groove at the front. There are special holders for this, with which you can turn them at the right angle over the grinding wheel. So if you don’t work with wood very much and need to sharpen your chisels every few days, then a cheap water sharpening stone for $20-30 can go a long way. Add a piece of leather, for example from an old belt, and a bit of grinding paste, and you can make the chisel razor sharp, definitely enough for woodworking. If you want to recreate my device for maintaining 25 degrees, you can find the instructions for this in the video description below. I wish you happy handicrafts and lots of fun stitching. Bye!
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