Troubleshooting and Tuning Wooden Hand Planes

A few posts ago I talked about dealing with a badly warped blade from a wooden bodied hand plane, and then addressing issues with the bed of a wooden plane. These posts might suggest that wooden bodied hand planes are not as reliable or as functional as their iron siblings and that they’re not worth the effort to bother trying to use. However, nothing could be further from the truth.

Personally, I love using wooden bodied hand planes. I don’t think they’re in any way better than iron bodied planes, and I use both wooden and iron bodied planes in my work. The wood certainly doesn’t know if it was planed by a wooden or iron bodied plane. I just really like the feel and feedback of wooden bodied planes.

However, tuning up an old wooden bodied hand plane is a bit different than tuning up an old iron bodied hand plane. Some of the steps are the same, or at least similar, between the two types. But some steps are unique to wooden bodied planes. So today, I want to discuss my process for evaluating and tuning up an old wooden bodied hand plane. I’m not going to be covering the tuning of wooden bodied hand planes in my upcoming Hand Plane Foundations course, so instead, I’ll cover my process here.

Sharpen the Iron

Before doing anything else to any plane (except maybe cleaning the grease and dirt off of it), the iron should be sharpened and the plane tried out. One of the most common mistakes that new hand plane users make is messing with the tool before they even know if it requires messing with. I blame the internet for this because there are so many “tutorials” on restoring and tuning up a hand plane. However, the simple fact is that many hand planes will work just fine as is, without any “tuning” other than sharpening the iron. If the iron has been sharpened and the plane has been tested and it still doesn’t work as desired, only then should you move on to “tuning” other aspects of the tool.

Identify the Symptoms

Assuming that the plane iron is adequately sharp, there are several maladies that can affect wooden bodied hand planes. These include (1) a plane that either doesn’t cut at all or will only take a thick shaving, (2) a plane that will chatter and/or skitter in use, and (3) a mouth that clogs with shavings.

Each of these issues can have one to several potential causes. The challenge is to identify the actual cause of the issue rather than “fixing” problems that may not exist. Therefore, I recommend only addressing one potential problem at a time. This is especially important for wooden planes because adjusting one thing could affect something else. So take it just one step at a time and try the plane after each change.

Not Cutting or Only Taking a Thick Shaving

One of the most common issues that a wooden plane will develop is a sole that is slightly concave along its length. This causes the plane to either not cut at all when the iron is set to take a light cut (because the concavity in the sole lifts the iron off the work), or to dig in and chatter because the iron has to be extended too far out in order to make contact with the board. This is typically a problem with smoothing planes and jointer planes (jack planes are meant to take a thick cut so sole flatness isn’t really an issue).

The solution, of course, is to flatten the sole of the plane. Fortunately, with a wooden plane, this is probably the easiest problem to correct. While an iron bodied plane might take hours of lapping to bring into an acceptable flatness, material can be removed from the sole of a wooden plane much faster, which can be a blessing and a curse.

With a well-tuned metal (or wooden) plane, planing the sole flat is probably the fastest and easiest method. With the iron backed off but snugly wedged in place, put the plane in the bench vise, sole up, and plane the sole flat. Take very fine cuts and check the sole frequently with a good straight edge and a pair of winding sticks because it’s very easy to take off too much material and widen the mouth more than necessary. The process is no different than flattening the face of any board. When done, the sole should be flat and free of twist. For flattening short planes, or coffin smoothers, clamp the jointer plane upside down in the bench vise and run the wooden plane over it like using a powered jointer.

Lapping the sole with sandpaper attached to a flat substrate is another way to make it flat. Be careful with this method though. Lapping a long wooden plane can quickly turn it into a convex soled nightmare if too much pressure or too aggressive of a grit is used. Making the sole convex is a condition that is much harder to correct. Therefore, I recommend not going coarser than 220 grit paper. Progress will be slower, but that just means things won’t go wonky as fast. Draw pencil lines about 1/4″ apart side to side across the sole of the plane to help gauge progress, and make sure the substrate is flat and well supported.

Brush the dust off the paper frequently to keep it cutting as evenly as possible and change the paper before you think you need to. Lapping causes the paper to dull fastest in the middle because the middle area is always in contact with the plane. When the paper dulls in the middle, the outside edges of the paper will cut faster than the middle, resulting in more material being removed from the outside edges of the plane than in the center. If the plane is currently concave, this can easily be mistaken as removing concavity. So don’t just rely on the pattern of the pencil marks on the sole to gauge your progress. Check the sole often with a straight edge and winding sticks to make sure you don’t go past flat and make the sole convex.

Use light pressure when lapping – just enough pressure to move the plane. Believe it or not, if too much pressure is used, a concave sole can flex slightly while lapping, giving the false appearance of progress when in fact the concavity is just being flexed out. The straight edge, however, will continue to show the sole concave, and you’ll bang your head against the wall trying to figure out why. The weight of the plane should provide most of the downward pressure. You just want to move the plane back and forth, without putting any significant downward pressure on it. Also, remember to keep the iron wedged in the plane while lapping to make sure the plane is under wedge tension. Just back the iron off so it doesn’t project out the mouth. This will provide the most accurate surface from lapping.

Chatter or Skitter

Chatter and skitter are two terms that are often used interchangeably. However, I like to define them differently, based upon information I read several decades ago written by the late Jeff Gorman. To paraphrase and simplify the two terms, chatter is an issue caused by an unsupported blade that flexes during planing. Skitter is when the plane engages and disengages harmonically and skips across the surface of the wood, like a stone skipped across a pond. The causes for these two issues are different, but it can be difficult to tell which problem you have as they appear to give the same result.

Skitter is typically easier to diagnose because it primarily happens at the beginning of the cut. The cause is either blade sharpness, blade projection, sole flatness, or planing technique. So the first solution for skitter is to sharpen the blade and set it for a lighter cut. If the plane won’t take a lighter cut, check the sole flatness and, if necessary, correct that. If the blade is sharp, and the sole is flat, make sure that the planing technique is good. Skitter usually occurs because not enough downward pressure is being applied to the front of the plane at the start of the cut. If the blade is sharp, and the cut isn’t too deep, it shouldn’t take a lot of downward pressure, but some is required.

If the solutions for skitter don’t solve the problem, you might be dealing with chatter. Chatter is the result of an unsupported blade that flexes and springs back during the cut, causing a ripple like planing pattern, even when the cut is very light. In old wooden bodied planes, seasonal movement over the last 150 years sometimes causes the bed to take on a slightly humped profile. This makes a wooden plane all but unusable. I’ve actually found this to be a very common problem with old wooden planes.

Addressing a hump in the bed of the plane might seem like a difficult task, but it really isn’t, and fixing this issue usually makes a drastic and immediate difference in how a wooden plane works. To check the bed, put the iron assembly in the plane and snug up the wedge. Turn the plane over and try to insert a thin feeler gauge between the iron and the bed (a thin piece of paper will work too). You should not be able to insert the feeler gauge past the iron’s bevel. If you can, then it means that the iron is not well supported behind the cutting edge and that it is likely flexing in use. This causes chatter.

Re-bedding the iron is easy, and much easier to demonstrate than write about. I recently posted a video on the process. So if your plane has this problem go watch that video and use the process to fix your plane’s bedding issue. When done, a feeler gauge should no longer be able to slide under the iron.

Mouth Clogging

This is probably the most common issue that I see with old wooden bodied planes, and there are multiple deficiencies that can cause it. A plane that cuts well but has problems with mouth clogging may have one or all of these issues, so it pays to check the tool carefully and address one of these issues at a time. In the end, all of them may have to be fixed in order to stop the clogging. It’s a frustrating problem to troubleshoot and address, but fixing it will make the tool much more pleasurable to use.

The first thing that I check when I have a plane with a mouth that clogs is how well the chip breaker mates with the iron. If there is any gap between the chip breaker and the iron, shavings can get caught in that space. Once a shaving gets caught, every bit thereafter will jam up behind it and clog the mouth solid. So this is the first thing to fix. I simply use a file or diamond stone to dress the bottom edge of the soft steel chip breaker until it contacts the blade all along its front edge and I can no longer see light between the assembled pair.

The second most common cause of mouth clogging in a wooden plane are the wedge tips. Quite often, the wedge has shrunk narrower than the mortise, so the tips of the wedge are not in contact with the sides of the wedge mortise. You can usually see if this is the case by looking through the mouth of the plane and observing the tips of the wedge. You might need a flashlight to do this. If the wedge has shrunk, you’ll see a space between the tips of the wedge and the sides of the wedge mortise.

If the wedge has shrunk, shavings are almost guaranteed to get trapped in these spaces, especially when the plane is skewed, because skewing directs the shaving right into them. To fix this problem, you can glue a thin piece of wood to either side of the wedge and reshape the wedge to tightly fit the sides of the wedge mortise. Alternatively, you can make a new wedge. While this is a bit more work, I’ve found that it is sometimes easier than repairing the original wedge when the wedge tips are severely damaged.

The last issue that might be causing the mouth to clog is a rough throat. Often times, previous owners of the tool have used sharp objects like a knife or awl to dig shavings out of a clogged mouth, damaging the front of the throat in the process. Shavings can then catch on the rough surface, clogging the mouth even further, necessitating more barbaric gouging to clear the mouth again. Of course this only serves to exacerbate the problem. Usually, the clogging was actually caused by one of the previous issues, and had the previous owner addressed that issue they would not have had to violate the tool time and time again to clear the clog. Nonetheless, now we have to address multiple problems.

To fix the rough throat, material will have to be removed to smooth the surface again. This can usually be accomplished with some careful chisel work and filing, however, it usually results in the mouth of the plane being opened a bit. This may not matter if the plane is a jack or jointer plane. It may not even matter if it is a smoothing plane. As with any of these repairs, try the plane and see how it works before you think about doing anything with the mouth.

Thoughts on Mouth Patches

Some people advocate adding a patch to the sole of a wooden plane to close up the mouth. I’ve never bothered to do this myself, although I have seen some examples of old planes where this was done. My opinion is that for the furniture woods that we tend to use most often, mouth tightness isn’t as important as it’s sometimes purported to be.

Honestly, I’m not entirely sure that these old planes ever had or were intended to have ultra tight mouths. I have seen (and purchased) old wooden planes that were virtually unused, and the mouths were nowhere near what would be considered tight by today’s standards. I’ve also not encountered a typical furniture wood where I felt a plane with a tighter mouth would have been helpful.

Perhaps a tight mouth would be helpful in a smoother designed to tackle really nasty exotic hardwoods with super gnarly grain. Maybe a tight mouth could be helpful in a single iron plane (i.e. a blade without a chip breaker). However, in a plane with a chip breaker, I don’t think mouth opening really matters. In fact, there is scientific research that suggests that by using a chip breaker, mouth opening is completely irrelevant. So, I’d pass on the mouth patch for now.

Wooden planes are a real joy to use when they’re working well, but can be extremely frustrating when they’re not. Hopefully, these tips will help you get that old wooden plane of yours back into prime working condition.