Oh,1

Back to the topic of my post “The Work Starts Here” about sharpening, specifically grinding. I’m convinced that grinding is where most new woodworkers can vastly improve, or at least become more confident in their hand tool use. In the previous post, I briefly addressed the wheels on a grinder, but there is more to consider than just upgrading from carborundum.

The shape of the wheel surface can make a huge difference. When using friable wheels, the wheel is also shaped by the act of grinding. Keeping the wheel dressed is essential to consistent results. I like to keep a slight crown on my wheels (shaped with a diamond dresser), which helps me focus the point of contact. It might seem like a dead flat wheel is the best way to get a dead flat blade, but the wider contact can make it tough to manage the heat build up. If I want a dead flat edge, I grind it with a nearly imperceptible hollow along the edge and use my flat stones to remove that hollow. A blade ground dead flat is likely to crown ever so slightly while honing, unless the stone and technique are perfect (honing guides can help). A flat edge is important when edge jointing boards, which I do a lot of for seat glue ups, and the #7 plane blade is wide, so getting the edge flat takes extra focus.

I do use CBN wheels that are flat faced, but I bias my pressure to one side of the wheel as I grind to ensure I know where the action is happening. CBN (cubic boron nitride) is a diamond hard mineral that cuts beautifully and leaves a very precise grind. The wheels are heavy and the metal mass helps disperse heat, plus, the good ones run absolutely true. I’m a huge fan, although they are expensive… really expensive. I still think they are worth it. They don’t spray sharp particles in the air like friable wheels and if you put a magnet under your tool rest, most of the metal will just collect there. I use wheels from Woodriver, because the grit wraps around on the right side of the wheel which helps with drill bit grinding.

What grit you ask? Well, that depends. I think choosing the right grit is a source of trouble for grinding newbies. The problem is that a coarse grit will hog of material at a frightening speed, so it seems wise to switch to a finer wheel. But the slower cutting wheel and tends to heat up rapidly because of the increased surface contact. Like so many processes, using the gross tool as far as you can is the wise move, just lighten up the pressure. I like the way that the condition of the CBN wheel never changes, so sensing the contact is a bit more clear than friable wheels where the condition of the wheel is always changing and needs dressing. I have 120 and 180 grit wheels. The manufacturer claims that they might clog if you use them with high carbon steel, which is most hand tools and you should only use them with high speed steel, such as turning tools. I’m not sure why they say that, I avoid non hardened steel, but otherwise haven’t had any issues. I will be looking into some of the CBN wheels with rounded faces for the reason that I mention above.

Now, as alluded to in the title, I suppose I need to wade into the contentious topic of steels. There are so many, with reported advantages and discovered disadvantages. For the most part, I don’t spend time thinking too hard on this topic, but if I have to say, then I am a proponent of good ol’ fashioned O-1. Its oil quenching steel that is relatively soft compared to many newer formulations. Why prefer a softer steel? That doesn’t sound right. But there is always a trade off. I can get super sharp edge with O-1 very quickly, which means I am likely to stop and sharpen more often. The “harder” steels available might have longer lasting edges, but getting them sharp takes more effort and depending on your process, may not get as sharp as O-1. It comes down to my inherent laziness. If my O-1 tool needs a touch up, I can do it fast enough that my motivation to see the tool cut better carries through the process. Even a subtle slowing of the process will trigger my time tested impatience. That said, I’m not overly concerned with which steel I’m using, but when choosing, I stick with the malleability and sharpness of the O-1. I’m not a zealot and would be happy to hear your experience with different steels. Happy Grinding.