Sharpening Hand Planer Blades
In the old days people would have entire factories lined with hand planers and now they are replaced by more modern automated machines like jointer planer combos. Nevertheless, there are individuals who prefer the hands-on approach of hand planers and if you're one of them one of the most important skills is learning how to sharpen your blade. Your planer needs a sharp blade in order to give you accurate performance.
Keeping your blades sharp is important in order to protect yourself and produce the best wood. Fortunately, hand plane blades are a lot easier to sharpen than power planer blades. If your hand plane blade is blunt, you're not only going to get below average performance but you're also more prone to triggering a kickback. The board could simply launch back in your direction and injure you. This never happens when you’re using a sharp blade.
There are professional full-time sharpeners who can sharpen the blade for you and they have the most experience with all the sharpening tools you need. However, doing it on your own is a rewarding experience as you're not confined to a single sharpening method - there are dozens of methods for blade sharpening and they vary based on your budget and the tools you have on hand.
Tools You Need
If you're a beginner the best way to imagine the sharpening process is as a progression between different grits. The idea is to start using a number of grits from the lower level and then make your way up to the higher levels. As you advance through the different grits you have to remove the leftover scratches from the layers and continue doing so until you get to the final stage.
There are dozens of tools you can use to sharpen your blade efficiently, starting from different grits to water stones. Water stones are the most reliable but they can be pricey and if you don't have the money to invest you could simply glue sand paper to a flat surface and use 60-400 grit pieces on the same principle. All you need to do is grind your relief angle, repeat at the cutting edge and remove the burr.
To get the best results you need to use stones. They are more commonly referred to as "water stones" or “Japanese stones” and we recommend water stones ranging from 600-grit all the way up to 8000-grit. You should start by purchasing 3 main stones: 600-grit, 1000-grit and 8000-grit.
King Two Sided Sharpening Stone with Base 1000/6000
BearMoo Sharpening Whetstone 3000/8000
King Combination Waterstone 800/4000
You're also going to need a "guide" which is a simple metal piece designed to keep your blade at the correct angle (usually 25 degrees). The guide doesn't have to be the movable kind, any basic guide will do.
How To Prepare For Sharpening
Start by focusing on the surfaces. Prior to initiating the sharpening process you have to prepare the flat surface and position the stones correctly. If your water stones are not flat you're not going to sharpen the blade correctly. You need to secure a flat surface or a plate to be able to place your stones on top of it. If you have a bigger budget you could purchase diamond plates but if you don't you could do away with simple 60-grit sandpaper glued to a board.
- Position the stones on a flat surface and moisten in water.
- Flat out the back and position the bevel edges correctly.
- Sharpen the cutting edge.
- Remove the burr with a smooth stone.
You must check if the blade has a flat back and if doesn’t adjust it before you get started on the sharpening the cutting edge. This is commonly the case with newer planers and you should take your time to get it right because you only have to do this once and it's not a repeating process.
Start by taking your water stones and lining them up in a way that you can establish progression. This means your 600-grit stone should come first and then you can make your way up to the smoother stones until you get to the 8000-grit stone. The goal here is to even out first inch or two, you don't have to go over the whole back. Start by moistening the plates with water and proceed by rubbing the iron using back and forth motions for about 30 seconds on each grit (progressively). Once you get to the final grit you're going to feel less resistance but still take your time and do it slowly. The whole process should take a few minutes and in the end you will see a new polish uncovering. This is when you know you have a solid flat back.
Once you're done with the back, take the blade and flip it over in order to start working on the bevel edge. You've already gone over the flat side and that side won't need a lot of work in the near future.
This is when you're going to need your guide in order to hold the blade at an ideal angle of 25 degrees. Hold it in position make sure it's moistened in water then start by grinding the bevel slowly until you see a fresh polish uncovering, similar to what you saw when you went over the back. To grind efficiently you can do simple left-to-right or top-to-bottom motions and you will effectively polish your bevel edge.
Sharpen The Cutting Edge
This is the most important part and the main reason you're here. Assuming you've prepared the surface, laid out the water stones, gone over the back and the edges you get to actually sharpen your cutting edge. Our goal here is to make it so the blade comes out straight and the process has to be done slowly in order to prevent the temperature from overheating.
Start by placing the edge on top of your 600-grit water stone and tilt the back end upwards. We recommend a slight tilting of around 30 degrees which should make it so that only the bevel edge is getting sharpened. You'll know you have the perfect angling if you can see a bit of light leaking between your water stone and the back. Make sure that the front end of your cutting edge is in touch with the stone.
Now that you've positioned your blade for sharpening, you need to go over the progressive grit motions similar to what you did when you were flattening the back. Run a series of left-to-right and top-to-bottom motions for about 30 seconds on each stone. Make sure the stones are moistened in water. Change the pressure you apply with your fingers in a progressive manner to make sure you're not applying too much pressure. You'll notice the final 8000-grit water stone is the one cutting the fastest but the blade sticks to it and this is where you want to go slower and take your time. As soon as you're done you're going to notice fresh metal revealing at the tip of your cutting edge. This is a good indicator you have a sharp blade.
Note: You're still not done because you'll notice a small burr developed in the back of your plane and you need to remove it. This happens once you've gone over the grits and the only thing you need to do to remove the burr is to use your finest 8000-grit stone (to even it out). After removing the burr you'll be left with a sharp blade.
How To Test Sharpness
The best way to test if your blade was sharpened or not is to try shaving off some hair from your wrist. This is a common test in trade school. If you sharpened the cutting edge you'll notice you can cut the hairs with almost no pressure. Alternatively you could use a simple plastic pen and see if it instantly catches on or if it skids. If you notice it skids you have a dull edge and you should repeat the process.
It's really easy to tell if you have a sharp cutting edge. All you need is to put it under strong light and notice if it starts reflecting light. If it reflects light you have a dull edge. The radius of the edge reflects the light and if you have no radius (which is what we're trying to achieve here) the light won't reflect.
As a final note, check whether there is a level of reflectivity in your meeting edges. This is another solid indicator. You want it to reflect in a manner similar to what you can see when you look at a window. This is how you’ll know you’ve successfully sharpened your blade.