Sharpening Chisels And Plane Irons

We've tried just about every system for sharpening there is. Here's how to get the best possible edge with the least amount of fuss.

When I took my first class in woodworking, the first thing the instructor showed us was his waterstone pond. For more than an hour he talked about secondary bevels, wire edges, and polishing the back of our edge tools. I kept looking at the rows of backsaws and chisels and wondering when he was going to get to the important part.

Within a week we all realized we should have paid more attention to the sharpening lecture. Soon there was only two sharp chisels in the shop and 10 students. I made it a point to learn to sharpen well. I've used a variety of methods including: oil stones, diamond stones, ceramic stones, sandpaper, and electric grinders. Each system has it's good and bad points. Some are simple, others do not make a mess. Most systems can pit a really good edge on tool steel. For me, the two most important qualities a sharpening system needs are that it must be fast and produce the keenest edge. I want a good edge in a hurry. That's because I'm more interested in woodworking than I am in the act if sharpening. I want to be done with it and get back to the good part.

The steps I'm about to show you will work with every sharpening and honing system I know of on the market. No matter what system you use, sharpening is about one thing: Grinding and polishing the two intersecting planes of a cutting edge to as fine a point as possible. Here are a few words af advice: Pick a sharpening system and stick with it for a good long time before you consider giving up. If you stick with one system, your edges will improve gradually as you get better and better at using your particular set of stones or sandpaper.

Second, buy a honing guide. These simple and inexpensive guides are quick to set up and ensure your edge will be perfect every time you sharpen. I use a $ 10 Eclipse-style guide for sharpening my chisels and most plane irons. I also use the Veritas honing guide. It's perfect at sharpening skew chisels and specialty plane irons that will not fit in the Eclipse guide, such as irons fit shoulder planes. Use the same guide over and over and your bridges will come out the same same time.

There are three sharpening operations that must be performed on all plane irons and chisels. First you must polish the flat backside of the tool. Next you grind the cutting bevel. Finally hone and polish a small part of that cutting bevel. Keep in mind that these three steps are only for tools that you have newly acquired. Once you do these three things, maintaining an edge is easier. Most sharpening is just honing and polishing the cutting bevel.

Begin with the back side of the tool. It's one-half of your cutting edge so you need to get it right. Start sharpening by rubbing the backside back and forth across a medium-grit sharpening stone. You do not need to polish the entire back, just the area up by the cutting edge. I begin the process with a 1,000 grit Norton waterstone, then do the same thing with the 4,000 grit, and then the 8,000 grit stone. The backside should look like a mirror when you're finished.

The next step is to grind the cutting bevel of the tool. You can use an electric grinder that has a tool rest, or you can use a coarse sharpening stone. I grind using a diamond stone for three reasons. First, it will never destroy a tool due to over heating (which can happen with electric grinders). Second, I use the diamond stone to flatten the waterstones. And third, the diamond stone is great for touching up my router bits.

Put the tool in your honing guide and set it so the cutting bevel is dead flat against the stone. I use mineral spirits to lubricate my diamond stone. It evaporates slower than water and will not allow rust to build up on the stone. Rub the cutting edge against the diamond stone and check your progress. You want to grind the entire cutting bevel all the way across. If you set the tool properly in the jig, this should be about 5 to 10 minutes work. As you progress, you should make a burr on the back side of the tool. This is called a "wire edge", and you'll want to remove it by rubbing the backside on your finest-grit stone a couple of times.

Honing is the fun part. The first thing to do is reset the tool in your honing guide. Loosen the screw that clamps the tool and slide the tool back about 1/8 "." Retainen the screw. "This will set the tool so that only a small part of the cutting bevel gets honed. you can see a secondary bevel appear up at the cutting edge. Once you have the burr, remove it by rubbing the backside across your 8,000-grit stone.

Polishing is a little different. You want to polish the secondary bevel with the finest grit stone. I use an 8,000-grit Norton waterstone. Work the secondary bevel and the backside on the 8,000-grit stone and watch the scratches disappear. When they're gond, you're done. Enjoy your woodworking.