Sharpen a Fore Plane
The fore plane is a traditional English tool used to get rough boards fairly flat so that you can then make them really flat with a jointer plane and ready to finish with a smoothing plane, scrapers and (sometimes) sandpaper.
Fore planes are supposed to be about 14″ to 18″ long. If you want to use an old metal plane as a fore plane, a No. 5 jack plane or No. 6 fore plane would be a good choice. I use a Hock Tools A2-steel replacement blade in my fore plane. A2 is a little harder to sharpen for me, but this modern steel takes a heck of a beating before it gives up, so it’s perfect for a fore plane. I also have a couple wooden-bodied fore planes that are nice because their light weight makes them less tiring to use.
Fore planes are supposed to have a curved cutting edge and are used directly across and diagonal to the grain of your board. Most people understand the idea of working across the grain (it allows you to take a deeper cut without tear-out). But many people are flummoxed by sharpening the curve on the edge. In fact, I’ve had about a half dozen readers send me their irons and ask me to do it for them.
Because I don’t want to open a sharpening service, here is how I grind and hone the curved edge of a fore plane’s iron. It’s a simple process. And if you take your time the first time you do it, I know that you will succeed.
This week I noticed that the edge of my metal fore plane was chipped up and the tool was getting quite hard to push. It was time to grind and hone a fresh edge. The first thing to do is mark the shape of the curve on the iron so I can replicate that shape. I use a curve that is an 8″ radius. I’ve experimented with lots of curves between 10″ and 6″ radii. I like 8″.
I have a wooden template that is the same width as my iron and has the curve shaped on one end. I place the template on flat face of the iron and mark the curve with an “extra fine” point Sharpie.
Place the template on your iron and trace its edge on your iron. A thin, consistent line is best.
Then I go to my grinder to remove all the nasty chipped-up metal. I keep my grinder’s stock tool rest set to always grind a 25° bevel. I don’t futz around with the tool rest. The first thing to do is to grind away the excess metal right up to your marked curve. This is done with the iron at 90° to the stone. I just balance the iron on the tool rest and go to town.
Grinding at 90° to the stone removes metal quickly to the shape you want and it creates a small flat on the edge of your iron. This is a good thing. The flat helps prevent your steel from overheating while you grind away the bevel at 25°. Thin steel heats up really quickly.
Hold the iron 90° to the wheel and show the edge to the iron. Remove all the steel right up to your Sharpie line. The first time you do this, take your time. It gets easy real quick.
When you get to the Sharpie line, put the iron flat on your tool rest and start grinding the bevel until the flat spot on the end is almost , repeat almost , gone. You remove the last little whisker of the flat on the sharpening stones.
Start by showing the middle of the iron to the grinder wheel. You’ll feel when the bevel is flat on the stone. Then sweep the iron right to grind up to the left corner. Try to keep the bevel in full contact with the wheel the entire time. Then repeat this process and sweep left.
Continue to grind and watch the flat shrink. Don’t use a lot of pressure when applying the iron to the wheel or you will cook your edge (it will get black).
Show the center of the iron to the wheel and sweep left or right. Here I’m sweeping right to grind to the left corner.
Here is my completed edge, ready for honing.
Here is the flat left on the tip of that edge. The reflection makes it look bigger than it really is. It’s a little less than 1/64″.
You can then hone the edge freehand. The edge doesn’t have to be perfect because the fore plane never produces a finished surface. However, you can use your cheap little side-clamp honing guide to help you (and your edge will look a lot sweeter, as well).
Put the iron in your honing guide and set the iron to hone a 30° secondary bevel. Place the iron on your coarse stone (#1,000-grit or coarser if you’ve got it). Put finger pressure hard on one corner of the iron and press that to the stone. Pull the guide toward you and shift your pressure to the other corner. This will feel awkward at first. But eventually you’ll rock it smoothly and naturally.
Repeat this process by starting with all your finger pressure on the other corner. If you are doing this correctly you should see an X-shape appear on your stone. Then it’s just like sharpening any tool.
Rock the edge back and forth as you move the jig. This might look hard. It’s not. It also tends to shape the wheel of your honing guide into a slight barrel shape , which is a good thing.
Remove the flat bit on the end of the iron , you’ll know it’s gone when you can feel a burr on the other face of the iron. Then move up the grits until you run out of grits or patience.
Now reassemble your chipbreaker and your plane. Sight down the sole of the plane and tweak the lateral-adjustment lever until the curve of the iron is in the center of the sole. This is easy to see.
When you are done sharpening you should have a nice even secondary bevel.
Then work directly across the grain of a board. Increase the projection of the iron until you are removing material quickly and can easily push the plane. The shavings should be thick , I shoot for 1/32″-thick with most woods.
You can probably take a larger shaving in a softwood, but I usually poop out if I try to take a shaving thicker than 1/32″ , but yet, that’s a lot of material for one stroke of a plane.
The fore plane is really useful for me, even though I have a nice powered planing machine. It allows me to remove material in a localized area with ease or to peel the edge off a rough board faster than my jointer (because I can work only the high spots). And it allows me to flatten boards and panels that are too wide for my jointer and planer.
Read more on all things plane-related in Christopher’s book “Handplane Essentials.“