Troubleshoot Your Plane

Plane Talk

Before launching into troubleshooting, let’s identify a plane’s basic parts. I cut open one of my No. 3 Stanley planes to give you a better look at how the parts fit together. We’ll start at the bottom and work our way up.

• The sole is the full length of the plane’s bottom.

• The frog holds the blade assembly at a 45- degree angle to the sole.

• The frog adjusting screw moves the frog forwards or backwards.

• Moving the frog effectively opens or closes the plane’s mouth, the gap in front of the blade.

• The uppermost part of the blade assembly is the lever cap.

• The middle part of the blade assembly is the chip breaker. It’s screwed to the blade.

• Pushing down on the lever clamps the blade assembly to the frog.

• This clamping pressure is regulated by the lever cap adjusting screw.

• Turning the depth-of-cut adjusting nut rocks the “Y” adjusting lever, which slides the blade and chip breaker up or down the frog.

• Pushing the lateral adjusting lever side-to-side levels the blade with the sole.

Click any image to view a larger version.

Problem 1:  

Your plane cuts at the beginning or end of a board, but not in the middle.

Cause

The plane's sole may not be flat. 

Solution

Rule out some simpler causes first. Test the board’s flatness with a long straightedge. If it’s hollow in the middle, the problem is with the board, not your plane. Similarly, test the flatness of your bench. If it’s hollow, the board will bend as you plane. Time to flatten the bench. But if your board and bench are just fine, and this mysterious behavior persists, chances are the sole of your plane isn’t flat.

A plane’s sole must be extremely flat for the blade to remove continuous, thin shavings the full length of the board, your ultimate goal. Test your sole by placing the plane on a very flat surface, such as a tablesaw’s cast iron wing. Try to slide a thin strip of paper underneath it at various places. If it slips under at any point, the sole isn’t flat enough. It needs lapping (a machinist’s term for flattening).

The easiest way to lap is using self-adhesive sandpaper on a rigid, flat surface, such as a tablesaw’s cast iron wing, a jointer bed, or a long piece of 1/4-in. plate glass. (You can also use regular sandpaper and a low-tack spray adhesive.) You may have to remove a lot of metal, so it helps to have a variety of grits available, from 80 to 220. The surface and paper should be at least twice as long as the plane’s sole. 

Retract the blade and start lapping with 120 or 150-grit paper (photo, above). If the sole is convex, grip the plane as shown to avoid rocking it. Inspect the bottom after a few strokes (photo, left). The newly sanded areas should be easy to see. If there are lots of low spots, switch to coarser paper. 

Whichever grit you start with, keep sanding until the entire bottom is scratched with sanding marks. The area right in front of the mouth is very important; it must be flat to prevent tearout. Don’t worry about the sole’s extreme ends, though, or old scratches from previous use. Once the sole is flat, work up to 220 grit or more to polish it.

Mark your sole with a felt-tip pen to help reveal the low spots. Planes with corrugated (grooved) soles have less metal to remove than planes with smooth-bottomed soles, so they’re easier to flatten.

Flatten your plane’s sole using sandpaper. A flat sole enables a plane to make long, thin shavings.

Problem 2:

You retract the blade to take a lighter cut. The plane works fine for a while, then suddenly stops cutting.

Cause

There’s backlash (play) in the plane’s adjustment mechanism.

Solution

Always set a blade’s final depth of cut by adjusting the blade downwards, deeper into the wood. If your blade cuts too deep, back it out until it cuts a very thin shaving or not at all. Then advance the blade bit by bit until the shaving is the thickness you want. If you overshoot, start over again.

To understand the “why” behind this procedure, let’s back up to the original problem. You’ve retracted the blade, and eventually it stops cutting. What’s happened is that the blade has slowly crept back up the frog. If you remove your plane’s lever cap, you can see how this works. 

Turn the adjusting nut clockwise to advance the blade, then counterclockwise two turns to retract it. Hold the blade with your fingers and push it up the frog (photo, left). It will move by at least 1/32 in. That’s why the blade stopped cutting.

Now turn the adjusting nut clockwise again, two full turns, to advance the blade. Try moving the blade up the frog with your fingers again. It shouldn’t budge.

Backlash is the problem. (“Backlash” is the play between mechanical parts.) In a plane, there’s often significant play in two places. First, there’s play between the adjusting nut and the “Y” adjusting lever’s fork. Second, there’s play between the top of the “Y” lever and the slot in the chip breaker. Some planes have more play than others, but there must be some play in any plane or the parts won’t move. It’s usually impractical to alter the plane to remove backlash, so the best strategy is to learn to live with it.

Problem 3:  

Your plane suddenly stops cutting. When you take it apart, you find shavings wedged between the blade and chip breaker.

Cause

There’s a gap between the blade and chip breaker.

Solution

First, lap the chip breaker’s bevel, located under the breaker’s leading edge (photo, below). The angle of this bevel is important. It must be steep enough so that the bevel’s point, not its heel, touches the blade. With most chip breakers, if you keep the screw hole aligned with the sandpaper’s edge, the bevel’s angle will be just fine. Keep lapping until you feel a wire edge develop along the chip breaker’s entire width, just as in sharpening a blade. 

The second step is to round the top of the chip breaker. You can use a file if the chip breaker is quite blunt, but sandpaper usually works well enough. Use a rolling motion to create a rounded edge, ending up at about 45 degrees (middle photo). Keep sanding until the wire edge you formed earlier is gone, then alternately sand both the bevel and the top until the chip breaker is sharp. 

When you’re done, hold the chip breaker firmly against the blade, as if it the two were clamped together by the lever cap. Sight from behind the chip breaker. There should be a slight gap at the heel, but no light showing between the chip breaker and blade.

To eliminate gaps between the chip breaker and blade, begin by lapping the bevel underneath the chip breaker’s leading edge. Keep the chip breaker’s screw hole aligned with the sandpaper’s edge to form the bevel at the correct angle.

Round the top of the chip breaker to create a sharp edge. Lift the cap iron up as you drag it across the sandpaper.

Squeeze the blade and chip breaker together to inspect for gaps. No light should be visible between them. In addition, the chip breaker’s heel shouldn’t be touching the blade.

Problem 4: 

Your blade chatters. It feels like its bouncing up and down as it cuts.

Cause

Your blade may not be clamped down tight enough, or your frog may not be flat. 

Solution

Try simple fixes first. Your blade may be dull, or set too deep, or your chip breaker may have slipped over the blade’s edge, so it’s trying to do the cutting. If you rule out these causes, try the following:

First, increase the clamping pressure on the blade. This is controlled by the lever cap adjusting screw (photo, below). This screw isn’t something you fiddle with every time you plane, though.  Adjusting it is a matter of finding the sweet spot that puts lots of pressure on the blade, but not too much. If you overtighten the screw, applying too much pressure, you won’t be able to turn the large brass wheel that controls the depth-of-cut. 

To find the sweet spot, loosen the lever cap and tighten the screw 1/8 turn. Re-tighten the lever cap. Turn the brass adjusting nut to move the blade up and down the frog. If it moves very freely, loosen the lever cap again and tighten the lever cap screw another 1/8 turn. Re-fasten the lever cap. Repeat this procedure until the adjusting nut is somewhat hard to turn with two fingers, but not too hard. Once you’ve found the best setting for the screw, leave it there. You should rarely have to re-adjust it.

A second cause of blade chatter may be a frog that’s not flat (photo, below). To check your frog, unscrew it from the plane’s body and remove the lever cap screw. Lap the frog on sandpaper. You won’t be able to lap the entire surface because the Y lever sticks out the top, but that’s OK. Flattening the first two to three inches’ worth is good enough.

Your blade will chatter if the lever cap doesn’t provide enough pressure to clamp the blade tight to the frog. Adjust the lever cap screw to provide more pressure, if needed.

Your blade will also chatter if your frog’s top surface isn’t flat. Flatten the frog with sandpaper adhered to a flat surface.

Problem 5: 

Your smoothing plane leaves tracks on a board’s surface.

Cause

The blade isn’t level, or its corners are too square.

Solution

First, make sure the tracks you see aren’t ridges caused by a nick in the blade. If the tracks look like shallow steps (drawing, below), one side of the blade is cutting deeper than the other. Raking light or chalk used flat-side down clearly reveals these tracks. 

You’ll have more success avoiding track marks and leveling your blade if you round it (photo, below). This prevents the corners from digging in. Rounding a smoothing blade’s profile one way or another is an old tradition. Here’s how I go about it. First, I round over the blade’s corners on the grinder. I do the rest of the rounding work when I hone, by rocking the honing jig to one side or the other on the pull stroke (photo, above right). This creates a cambered edge and a transition to the rounded corner. 

If you’re new to planes, I recommend you camber the blade’s full width. The amount of curvature to aim for is very small. To check it, I hold the blade upright and lay the fat side of a small square on the blade’s edge. The blade’s center should be higher than the edges by about the thickness of one or two pieces of paper.

If you’re more experienced with a smoothing plane, it’s better to leave the majority of the edge straight across, and only camber the outer edges; that is, round 1/8 to 1/4 in. of each side. This will create a flatter surface than the previous method, but the blade will be more difficult to level.

To level your blade, make a narrow shaving using the outer 1/2 in. of the blade’s left side. Make another shaving using the right side (photo, below. Compare the thickness of the two shavings. Adjust the lateral lever until the shavings are equally thick. Back off the blade, re-adjust its depth of cut, and you’re good to go.

Round a blade’s profile by rolling the jig sideways as you hone. Favor the right side, then the left side on alternate pull strokes to produce a curved profile.

Level your blade by comparing shavings made with each side. Hang the plane off the edge of a board and make a narrow shaving using only the blade’s left side. Turn the plane around and make another narrow shaving using the blade’s right side. Adjust the lateral lever until these shavings are equally thick.

Shallow steps are caused by a plane blade that’s not set perfectly level. One corner is digging in.  A commonly used method to minimize this problem is to round the blade’s corners, and maybe its entire profile. This produces a surface with extremely shallow valleys, which are leveled by scraping or sanding.

Round a smoothing plane blade to avoid making steps on a board’s surface. The corners of this blade are rounded off, and the area in between is cambered (that is, very slightly curved), or left straight.

Problem 6:

You get tearout, even though the blade is sharp.

Cause

The chip breaker is set too far back, or the plane’s mouth is too large.

Solution

First, adjust the chip breaker closer to the end of the blade (photo, below). Second, move the frog forward to close the plane’s mouth (photo, below).

In general, the finer the shaving you’re trying to cut, the closer the chip breaker should be to the blade’s edge. A 1/32 in. setback is ideal for most hardwoods, but when you get tearout, try moving the chip breaker to within 1/64 in. or less of the blade’s end. This will make the plane harder to push, however. (In soft woods, like pine, where tearout isn’t an issue, you can adjust the chip breaker up to 1/16 in. back from the blade to make the plane easier to push.)

To move the frog, remove the lever cap, blade and chip breaker. Slightly loosen the two bolts that hold the frog to the sole. Reinstall the blade assembly and adjust the blade until it barely sticks out of the plane’s sole. Turn the frog adjusting screw with a long screwdriver to close the plane’s mouth. Once you have created the desired opening, remove the blade assembly and tighten the bolts that secure the frog. Tighten each one a little bit at a time, like a car’s lug nuts. 

Moving the frog may skew it, however. On most planes, you can only eyeball the frog to make sure it’s front end remains parallel to the plane’s mouth. Frogs on Stanley planes manufactured in the Sweetheart Era, roughly 1920 to 1935, are self-aligning, so skewing isn’t a problem (photo, below).

Tip: Rub your plane's sole with a few squiggles of paraffin or canning wax every ten strokes or so. This helps your plane glide much more smoothly.

This story originally appeared in American Woodworker July 2007, issue #129.

July 2007, issue #129

Purchase this back issue.

To reduce tearout, adjust the chip breaker closer to the blade’s edge. A projection of 1/32 in. is normal for most hardwoods, but to beat tearout you may have to go down to 1/64 in. or less.

To further reduce tearout, move the frog forward by turning the frog adjusting screw. This closes the plane’s mouth. Normally, the mouth should be about 1/16-in. wide. You can reduce it down to 1/64 in.

If you move the frog forward, you must double-check that it hasn’t wiggled side-to-side and become skewed. Many older Stanley planes have an alignment tab to prevent skewing, which is an excellent feature.