Do You Need to Flatten the Sole of a Hand planer? a Clear answer

A hand planer that comes out of the box is far from ideal for producing the best results. To begin, you must take care of the hand plane blade and sharpen it, as described in my previous article, and set the blade correctly.
But what about the sole of the hand plane?
You are no doubt aware that its flatness has a significant impact on your results.
Can you rely on the manufacturer to make the sole perfectly flat, or do you need to flatten the sole of a hand planer first?

Yes, flattening the sole of a hand planer is required, preferably prior to use. Only then can you be confident that you will achieve the best results. Do not rely on the manufacturer’s claim of flatness; other factors, such as temperature, can cause the hand planer’s sole to flex.

I’ll explain why flattening the sole of a hand plane is so important, as well as when and how to do it, in this article. In addition, I’ll share one tip that will make a big difference when using the hand planer and that few people talk about.

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Why do you need to flatten the sole of a hand plane?

Different manufacturers and qualities of hand planes are available. More expensive hand planes will be of higher quality, and the sole flatness will be much better than cheaper models. But don’t rely entirely on it. More expensive models may also have a non-flat sole, which is not always the fault of the manufacturer.

Hand plane bodies are made of steel, and steel can change due to heat and cold exchange or exposure to extreme temperatures. This temperature change may occur during transport, resulting in a hand planer with a twisted sole.

However, the sole can also flex as a result of use. Did you know that you can easily bend most metal molded surfaces by bending the handles by applying pressure during use? This will alter the shape of the sole and eventually destroy it.

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How do you check the flatness of a hand planer sole?

Before investing the time and effort to flatten, make sure the surface is flat. Start by setting up the hand planer on a level surface; I’ll explain which is best later in this piece. There are two methods for determining sole flatness.

The first and most trustworthy method is to use a feeler gauge. Pushing it under the sole in different places will allow you to see where the sole makes contact with the ground and where it doesn’t. If the gap is too wide, it needs to be smoothed out.

If you don’t have a feeler gauge, you can use a piece of paper as an alternative. Printed paper is about 0.1016 mm (0,004 inches)

When do you need to flatten the sole of a hand planer?

It is best completed when you get a new hand planer. To ensure that the hand planer is correctly set and that you get the best results, flatten the sole of a hand planer before you begin using it.

To ensure flatness, you should repeat the flattening procedure from time to time. Keep in mind that pressure applied to the hand planer while working, as well as temperature variations in your workplace, might cause steel to bend.

The aforementioned elements will determine how much the sole has to be updated. How well-made is your hand planer? How much pressure do you use when working? What kind of climate do you have in your workshop? So check the sole regularly to make sure it is flat.

How do you flatten the sole of a hand planer?

Watch the video here & learn how to flatten the sole of a hand plane

Here you can watch the video and see how I flatten the sole of a hand plane.
After watching the video, you can continue reading the step-by-step guide on how to flatten the sole of a hand plane.

How to flatten the sole of a hand plane – Step by step

Flattening the sole of a hand plane seems complicated, but it is actually very simple. What you need for this is a flat surface, which I mentioned earlier in this article. It is best to use a piece of glass for this. Glass is a material that you can say with 100% certainty that it is perfectly flat. I hear others use materials like granite for this, but I like to stick to glass. Before you start, it is best to remove all the dirt with a glass cleaner. This ensures that no small irregularities can arise that cause deeper scratches in the sole.

Flatten the Sole of a Hand planer - Use a flat surface such as glass
Flatten the Sole of a Hand planer – Use a flat surface such as glass

After that, you can place a piece of sandpaper on the glass. I always start with 80-grit sandpaper.

Before taking any further steps, it is best to lift the blade into the hand planer. Lift it as high as possible so that it cannot come into contact with the sandpaper. I would not recommend removing the blade. The blade is always held in place by the lever cap, using great pressure. This creates stress on the steel that ultimately determines the shape of the sole. When you remove the blade, the stress on the steel is different during sharpening and can deform again when the blade is put back, causing the sole to bend.

To figure out how much metal to remove and where the sole is flat, I employ a straightforward approach. With a sharpie, create a grid on the bottom of your palm. With the sandpaper, you may now sand the hand plane. Checking in frequently is what you must do until the grid is entirely gone.

Flatten the Sole of a Hand planer - Draw a grid on the sole
Flatten the Sole of a Hand planer – Draw a grid on the sole

Please be aware that you will need to spend some time here if you have severely malformed soles. The initial smoothing of a hand planer sole might take several hours. But don’t let this discourage you because a flat sole will offer you a lot of benefits.

Flatten the Sole of a Hand planer - Flatten on a 80-grit sandpaper
Flatten the Sole of a Hand planer – Flatten on a 80-grit sandpaper

Once you are sure the sole is flat you can switch to 120 grit sandpaper and make about 20 strokes. After that, you can do the same again on 220 grit sandpaper.

Feathering the edges for better transition over the surfaces

The sole of your hand planer is now perfectly flat, but there is one more thing you can do to make the sole even better. That’s feathering out the edges.

When planing on uneven surfaces, the edge of the sole can sometimes cause your hand planer to get stuck. That’s why it’s good to feather out the edges. You do this by placing a thin piece of metal, such as a ruler, on the sandpaper.

Flatten the Sole of a Hand planer - Use a thin piece of metal to feather out the edges
Flatten the Sole of a Hand planer – Use a thin piece of metal to feather out the edges

Place your hand plane on top with the edge just over the ruler and start moving the hand plane back and forth. Make about 30 turns, and you will see that the edges are gone. Repeat on the other side, but also on the nose and heel of the hand plane.
Then you can further touch up the sharp edges with a file and finish by oiling against rust.

Flatten the Sole of a Hand planer - Feathered out edge
Flatten the Sole of a Hand planer – Feathered out edge

How to maintain the sole of a hand planer?

You’ll want to keep your flat sole for as long as possible once you’ve achieved that. That’s why I have two simple tips to help you achieve this.

Store the hand planer in a specially designated place. Other tools that could come into contact with the planer and cause damage should be avoided. Provide a climate-neutral environment to prevent the soles from bending. Keep your workshop at a constant temperature and keep the hand planer away from extreme heat sources such as fire, gas burners, welding machines, etc.

Grease the sole of the hand planer and other parts to prevent corrosion. I always use WD40 for this, just like I do after sharpening my planer blades. My article, How I Sharpen a Plane Blade Until It Is Razor Sharp – Quick Guide, covers everything you need to know. You will notice that I use non-stick WD40 instead of regular WD40.

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