Are Grinders Bad For Our Tools?
No. Here’s why. Some people can worry and some others are convinced that if you use a grinder (implying something with power) you’ll get through three to four times as much tool steel. You see there is no difference in using a powered grinder compared to hand methods when we maintain our tools. The key is the grinder should never raise a burr. The only time our cutting tools become shorter is when we raise a burr. In fact you can waste just as much tool steel, if not more, by using hand methods. Okay, so lets break this down.
Grinding with power. These days the most common power grinding methods are bench grinders and water bath grinders. In addition there are hand cranked and belt grinders too. I fall into this camp, mainly using the water bath grinder. With all of these methods it’s rare to use them as a sharpening method in of itself, although it can be done. Most people, me included just use them to reduce the size of the honed bevel to a thin line but critically not raising a burr. This allows me to just use one honing stone which proves economical in the long term and gives me the flexibility to restore damaged tools on the grinder. This is the only time a grinder will shorten a tool, when we remove a chip. Thankfully this is rare, the last two times I needed to do this was restoring a second hand tool, the other was due to planing wood that had a small fragment of metal embedded in the surface.
Grinding by hand. Although some old shops would have large rub stones, these days most people who grind by hand use waterstones, diamond plates or coarse abrasive paper. Importantly, as a broad statement they choose to maintain a single or slightly convex edge to their tools. This means a sequence of steps starting with a coarse stone around 250 grit and ending up with something fine enough to suit the task at hand. That first coarse stone will raise a substantial burr, much more than if you use a power grinder. And that’s the step that shortens the tool. So you can see that grinding by hand does not save your steel.
Which is right approach? Both. The traditional method for dealing with Japanese tools is one bevel, the most often documented method for western tools is two bevels, a grind that never reaches the edge and a hone to finish. As long as we prepare an edge that allows us to progress our work to a high standard we’re good.
The takeaway? The reality is that you’ll find a system you’ll gel with. You might experiment a bit before you find the system you want to stick with. It used to easier, if you lived in the UK it was an oilstone and get on with it. We have choice and that’s fine, as always, do a bit of research and as is so often the case the right choice is usually not that expensive. While you’re learning you’re method, take your time and you’ll get the hang of it. Woodworking is hard on our planes and chisels, you’re going to get plenty of practice.