Tuning a Hand Plane

by John Gunterman (a.k.a. Spokeshave)

When you bring home the latest $20.00 yard sale #4 into the house and set it down on some newspaper and marvel to yourself how someone could let such a potentially fine tool languish in neglect for so long. Luckily you have the knowledge to revive this basket case and after several hours of attention, it could leave a perfect, finish ready, surface in curly maple and produce shaving so thin they have only one side, and they float upward when release from your hands.

The first thing you should do is try your plane in its "as found" state. Chuck up a hunk of wood in the vise and try and take a swipe.... How does it cut? Could it cut better? Sure! Let's make it so.

The first and most important thing that needs attention is the part that does the cutting, the iron. Release the lever cap and remove it and set it aside. Remove the cutter assembly, On most all bench planes it is a two piece assembly consisting of an iron and a chip breaker iron.

Now you are going to separate the two. But, before we do, let's take a moment to talk about shop safety...Be sure to read understand and follow all the...... and remember this, there is no more important rule that to NEVER do this, use your lever cap as a screwdriver! Now lets get started on today's project.

Remove the chip breaker and set it aside. Look at the back of the iron, has it been flattened before? No. Too bad for us...take a good look and check for pitting (rust that has gone below the surface) is there any pits to speak of near the cutting edge? Yes? Deep? Call Ron Hock. Wait a week for a replacement blade, then continue.

If the back is unpitted, (or you got a new blade) the first thing we need to do is lap it flat or at least the inch or two nearest the cutting edge, below the keyhole slot. This is very important as this is really the edge that does all the cutting, if it not as flat as possible it cannot cut as well as possible.

There are many schools of though about removing metal to produce cutting edges, This is not the place for that discussion, use your method of choice. Lap it flat and polish through successive grits till you can count nose hairs in the reflection. Stop.

We need a break from this hardened steel, lets turn our attention to the chip breaker.

First hold it up to the iron in it's natural position and look at the joint between the two. Are there gaps in it? How about the amount of "spring" in the arch of it? Does it really clamp down well when you snug the screw up? Could you twist the two apart by hand w/ the screw as tight as you can get it?

We'll put some spring back into the cap. I do this by placing the arch of the cap over a 3/4" dowel and beating on it with a urethane faced mallet. Don't worry, this is not hardened steel, it will handle it well. Okay now check how it mates w/ the iron. Using a file, fettle the leading edge so that the two meet at the tightest angle and the passing chip cannot get snagged in the union of the two. Also polish the face of the curve all the way to the top of the curve so that the chips just glide right over.

Next were going to work on the...anybody, anybody, Bueller? What's that? The bevel? Wrong! It's bezel and no, we are going to work on the side opposite the "back" which we'll call the front, even though that is wrong because it really IS the back of the iron, the part that bears on the bed of the frog, but since I've never really heard it addressed by anybody before...we'll stick to that and call this "the other side from the back" naaahh... "the front".

Start lapping and get it flat, the flatter it is the better it will bed and the less likely it will be to bind when adjusting or chatter when planing. Just get it flat.. it does not need the nose hair count test, but needs to be flat. Okay. That will do for today.

The next thing is the bezel...the intersecting slope cut on an angle between the face and the back, that which will be the back side of the cutting edge, if you will. Look at it. Can you might be able to tell how many times it has been sharpened by the number of facets on the face?;-) We're going to get us a good square true bezel again I like to use a wheel grinder here because it will remove a lot of material fairly quickly (but you can burn an edge if not careful) also it will create a hollow grind which is easier to sharpen and maintain between grindings. Here I'll turn to a 10" slow speed horizontal wet grinder. But use whatever means you have and grind a new bezel so that it is one continuos face from end to end, and square across the width.

Now sharpen the leading edge thought successively finer grits until the leading edge is polished and it the blade is sharp, if you go through your last few finer grits "freehand" and swing the blade back and forth in an arc, you will naturally induce a slight crown to the cutting edge. Otherwise just dub the corners, if you don't do anything, your corners are going to leave ridges in the work surface.. Now strop off the wire edge and lightly wax the entire blade to protect from rust. Rust is the enemy!

Replace the chip breaker, setting to from 1/32 to 1/16 back from the edge and place the blade back in the plane adjust as necessary and take a test cut. Does it work better? I sure hope so, we just did a lot of work! Can it work better? I'm sure of it.

How wide is the mouth opening? What do you mean mouth opening? OH... The gap between the leading edge of the blade and the trailing edge of the front of the mouth. For a smooth plane you really want to close it down to be no more open that necessary to pass the chip the blade is cutting. Take the blade back out and release the frog attachment screws and remove the frog. Is there years of accumulated shavings packed underneath rotting away? I thought so. Remember that, and clean it out every once in a while, okay?

Put the frog back in but don't tighten the set screws all the way, put the blade back in and the lever cap back in place...slide the frog foreword till the mouth is about twice as thick as the shaving you intend to take... I shoot for about 5Thou for a finely tuned smooth plane... hold the frog in place and carefully remove the blade and tighten the screws securely. Replace the blade and try the plane again? How's that working now?

This is about as good as your going to get without some serious work...ask yourself now "is this acceptable?"

To get any increased performance you might get out of the plane it will require working of the castings. To assure the sole is flat and the frog mates well and the like.

Back at the bench with your plane and ready to do some serious work?... Well, take a break and go get a precision ground straight-edge.. One longer than your planes sole, and while you are out get a sheet of 3/8" or better plate glass at least twice as wide as your widest plane and 3 times as long... oh and as long as you are out, pick up a sheet of 3/4" Birch plywood and some 1x stock some glue and screws.

While you are working on getting your flattening jig built (while the glue dries) you should take some time to remove and inspect the frog. Take it out and look at how it connects to the casting of the plane.. there are machined surfaces on the bottom of the frog and the frog receiver in the casting of the plane. These machined surfaces should mate well to provide a solid connection.

You may need to do some work w/ small files to get them to mate well... take your time and pay attention. It is not much work, so take care, and do it right. Also lap the bed of the frog (where the blade rests) out flat. Remember how you lapped the face of the iron? You want to do the same thing to the surface it bears on.

When these are done re-assemble the plane and re-adjust everything and take it for a spin. this is a about as good as you are going to get without some serious work. The flattening process is a PITA and will test your resolve! are you really SURE you want to do this? okay, lets rock.

First check to see if the planes sole is flat. How flat? well, "flat enough" in the right areas. You want the toe and heel of the plane to be in the same plane as the area in front of and behind the mouth, especially the front.

Hold your straight edge to the sole and hold the plane up between you and a light source and look for any gaps of light between the two. move it around really look well. Does the sole really NEED flattening?

Well, before we do that lets work on your flattening bench/jig. to make a planes sole flat you need a flat surface to work on. If the surface is convex or concave, your planes sole will be the inverse. So you want a surface as flat as is prudent. Now I don't expect everybody to have access to a 3 foot long Granite surface plate, and it REALLY makes a awful mess!

Plate glass alone will not do the trick...if it sits on a surface that is not flat, it will distort..

So to solve both problems I built a simple torsion box-based jig to create a flat surface and hold the sheet of glass. You know what a torsion box is right? Okay make one that is twice slightly bigger than you plate of glass. Now fasten battens to the top of the box so as to hold the glass in place while lapping an "L" forming a corner to the outside left corner for a right handed lapper. Also it needs to be just a tad lower that the top of the glass... you would not want to run into it w/ the plane, would you? :-) Then screw it to your bench.

Now take a long strip of Aluminum Oxide (Norton Blue) sandpaper (you can buy it in rolls) and glue it to the glass. Retract the blade and set the plane on the paper and rub back and forts gently a few times in long fluid strokes the length of the paper (which is at least 3x the length of the plane, right?) Flip the plane over and look at the sole. If it was discolored or rusty to begin with you should easily see where the high and low spots are. The high spots a are where the metal is fresh and shiny, the low spots are the dirty stuff.

Okay now you know what we need to do ... make the sole of the plane flat. Get a pitcher if Iced Tea and get busy.

After a while stop and clear the paper of the iron dust w/ a shop vac. back to lapping.. checking regularly w/ the straight-edge. When it is flat enough, you will know. Now it's time to polish the sole through successively finer grits of paper. It will take on a fine polish at about 600 grit. and going beyond this is simple folly.

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