Chris Schwarz's Blog

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 25Ã?° 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 90Ã?° 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 30Ã?° 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.   

- Christopher Schwarz

24 thoughts on “Sharpen a Fore Plane

  1. Adrian

    It’s been a while—March to September—but the wheels turn slowly, it seems. As suggested, I picked up an old #6. I used ebay. The plane is old. The price was good. I ground my radius and honed the blade and finally this weekend I gave it a real trial in flattening some quarter sawn cherry.

    I’ve made three observations.

    1. I found that when I worked perpendicular to the grain I got some fairly nasty tear out. I’m not sure if I should care at this stage in the process, but it bugged me. Working on the diagonal with the grain I seemed to get less tear out.

    2. I’ve been struggling with flattening for a while and it seems that somehow (I’m not sure how) this plane makes the job a lot easier. I don’t mean faster, I mean easier. Working with thinner shavings I seemed to spend a lot of time struggling to get the planes to remove material where I thought it needed to be removed (straightedge says bump but plane won’t cut), or trying to figure out where the material needed to come off. But with this plane the process seemed to happen almost by magic. I spent much less time puzzled about what to do next.

    3. After 3 boards I can see light reflecting off the edge, indicating, I assume, that it’s not as sharp as it could be. This seems like a pretty short blade life. How sharp does a fore plane need to be? (I have a tendency to put off sharpening much longer than I ought to.)

  2. Tim Sgrazzutti

    Very timely blog entry for me Chris……thanks!! About a week before this, I had put what I thought was a pretty extreme camber on an old Stanley iron to use in the #5 for hogging off some really high spots. Worked well, but after reading this, I checked my radius and it’s about 10". I’ll give the 8" a try and see if it works even better. The other thing that worked well about this, is that I also have a thicker LN iron for the #5 with a slight amount of camber to it. With the mouth set for finer work with the LN iron, it’s wide open with the thinner Stanley iron, so no frog adjustment is necessary between them. The different thickness irons make changing "modes" on the jack a snap.

    While we’re at it, I like the idea of doing this with a template, so the camber on your iron is consistent when it’s time to grind. Do you have suggestions as to what radii would be good starting points for my #4 smoother (always slightly cambered) and #7 jointer (I have one iron with camber, and one I keep dead straight)??

    Regards,

    Tim

  3. Brian Whittaker

    I believe that another use for a fore plane with a curved blade is planing the edge of a long board square to the face.

    With a blade ground straight and square, there are two ways of performing this operation. One is to tilt the plane left or right to plane down the high side of the edge, but then you lose the tactile reference of the sole of the plane on the board. The other is to fiddle with the lever that controls the angle of the blade, but that approach is time consuming, particularly if it involves trial and error. Neither approach is suited to mass producing accuracy, say in planing thousands of feet of boards for floors or wainscotting.

    With a long plane and a curved blade you can keep the sole flat on the edge of the board. If the edge is high on the left, move the plane to the left so that the centre of the blade takes the deepest cut where it is needed most. If the edge of the board is high on the right, shift the plane to the right, and once again the blade will take down the high part, always with the sole riding firmly and consistently on the wood.

    Old oil stones generally are lower or thinner in the centre and higher or thicker toward the edges. This configuration may not be a sign that the old time joiner could not be bothered to lap his stone or that it went through a generation of misuse by the joiner’s careless son who used it only for sharpening a pocket knife. It may be that the worn stone was perfectly suited to sharpening a plane blade with a slight curve. Like other tools the stone worked better after it had been worn in.

    Sometimes the problem is the solution.

  4. Adrian

    To say that I’m going to have to regrind the bevel (from 25 degrees to 33, actually) is true, but I think grinding a higher bevel on a blade takes very little time. Grinding the 2.5" radius, on the other hand, could take a long time.

    I’m not interested in getting a cheap old plane and trying to make it perform well. (I tried that once with an old Stanley.) And for that reason, I think I had blinders on when it came to the subject of the fore plane. The key point is that a fore plane doesn’t have to be tuned to work well. I can probably get something suitable for less than the cost of a new blade.

    Of course, if I want the A2 that Chris recommends then it’s not so clear. Maybe it makes sense instead to get a second blade for the bevel down jack plane that I have. It’s only 12" long, though, not the recommended 14"-18". My bevel up plane has a longer sole. That was my reason for thinking I might use it for this.

COMMENT