Handplanes have been made for hundreds of years. Lately, they have been manufactured by companies and sold to craftsmen, but before that era, it was very common for woodworkers to make their own hand planes.
This is why making a hand plane can be perceived as reserved for highly experienced craftsmen. However, using the right techniques, it's not very hard to make a working tool! This particular one is very tiny, and will not be used everyday. But it is still able to cut nice shavings!
Step 1: The Metal Body
For the metal body, I used 20mm steel square tubing. You plenty of option here, you can use any size you want, and even U channel if that's what you have. Steel square tubing has a radius on its edges, that I couldn't take off at the sanding step, because the walls are fairly thin, but I don't mind the radius on the final plane. If you want to avoid the radius, you can use thicker square tubing with thicker walls and sand down the faces until you have sharper edges. You could also use brass square tubing, which usually comes without radius.
To start, I traced the desired profile of the plane on one face of the square tubing. I also traced the location of where the blade will sit, and where the pivot point for the lever will be.
I roughly cut the profile using a hacksaw, you could also use an angle grinder or any other metal cutting tool. Since both ends of the body are rounded (one convex, one concave) I use a flat file and and half-round file to shape it.
Then, using the hacksaw again, I took of the top wall of the tubing, by cutting near the top edges. I then filed away the top couple of millimeters, to get rid of the radius.
Step 2: The Mouth and the Iron
the mouth is a critical part of any planes. It has to be square, straight, and the right size. I'm not trying to make the best hand plane, so the size of the mouth is not the main point for me. But generally, if you want a smooth surface and fine shavings, the mouth should be as small as possible. The mouth should be wider if you want to take heavier cuts. It this case, the mouth opening is twice as wide as the blade I use thick.
I used a Dremel tool with a straight carbide burr, angled at 45 degrees, to open the mouth. I then used needle files to refine the shape. I think a better method would have been to drill out several holes in line to remove material quickly, before using the dremel and needle files. the back edge of the mouth is filed at 45 degrees, to later match the angle of the iron. The front edge is filed square.
I made the iron using an old plane iron, so I don"t have to harden it. Since the original iron was larger, I had to cut it with and angle grinder. You have to be careful here: If the steel becomes to hot while you cut it, the edge will become soft. And the edge is very thin, so very likely to heat up quickly. As soon as the metal is almost hot enough to touch, quench it in a bucket of water to make it cold again. The blade has to fit loosely in the steel body.
Since you are working on the blade, it might be tempting to sharpen it now. However, I strongly advice to wait: you may manipulate the iron for tests or measurement, and you don't want to cut yourself. So sharpening the blade should be the last step of this project.
Now, onto the wooden parts of the plane. Cut two different pieces. The front piece needs to fit totally in the metal body. so cut it to fit tightly in the front of the steel part, between the mouth and the tip of the plane. Cut it a bit too wide using a saw, then plane it or sand it to make it fit properly. I used purple hear for this project, but you can use any hardwood you want. However, since this projects takes only a tiny amount of wood, it's a good opportunity to use nice wood, like a tropical hardwood or a burl for example.
The front piece is more tricky. I wanted the part that sticks out to be flush with the steel, so it's cut a few millimeters wider. I used a shoulder plane to make the lower part fit perfectly (or, as best as I could at least). I cut the angled part at 45 degrees. The iron will sit directly on the part of the piece of wood, that's why I took the time to plane it flat, and square, so the blade will not be skewed.
Once both parts fit in the metal body, I traced the shape I wanted, and used a saw, chisels and files to cut the rough shape.
Step 4: Gluing and Peening
I used 5 minutes epoxy to glue the pieces of wood in the metal body. You will have a stronger bond if you can roughen the inside surfaces of the steel, using sandpaper or the tip of needle files for example.
When the glue was set, I used a drill press to drill 3 through holes in the side of the plane. I used a 3mm twist drill meant for metal. Although drill bits specifically meant for wood exist, it this case, the metal drill bit works just fine: since the wood is between two metal layers, the drill bit can't really wander at the start, and will not blow out the wood on the underside.
I then used a hacksaw to cut a 3mm brass rod, I cut 3 pieces, 2 millimeters longer than the plane is wide.
I then used a hammer to drive the brass rods in the plane. They shouldn't be too hard to hammer in. I then peened both ends of the rods to set them permanently: with the plane sideways on an anvil (or any heavy piece of fairly flat steel), I hit the pin using a ball-peen hammer, with a lot of small taps, until I felt it was pretty solid. I then repeated on the other side of the pin, and then it's the same thing again for all 3 pins.
When everything was peened, I sanded the sides of the plane, and it serves two purposes: making the pins flush with the body, and also giving a nice surface finish to the steel. I did the same to the sole (the under side) of the plane. I used 120, 220 and 400 grit sandpaper.
Still using files, chisels and sandpaper, I rounded the wooden parts.
Step 5: The Lever Cap
To maintain the iron solidly onto the bed, I decided to use a lever: the piece will pivot on a forth pin above the iron, to lock the iron in place. One end of the lever is just pressing on the iron, and the other end has a threaded hole (M4), so a screw presses on the iron. I used an off-cut of a brass flat bar. I used a hacksaw to cut the rough shape. While I still had the flat surfaces of the brass bar, I drilled both holes, both at 3,5mm. It's the size you need to drill for a M4 thread. The other on was 3,5mm to fit the 3mm pin, I went for a loose fit so the lever pivots nicely.
Once the holes were drilled and one of them was tapped, I refined the shape with files and a sanding attachment on a dremel tool. I then hand sanded it to 400 grit.
Step 6: The Tightening Screw
To position the lever cap, I put the iron in place in the plane, and then the lever cap on it. This way, I could se where the hole has to be drilled in the plane, so the lever cap pivots over the iron.
After driving the pivot pin in the plane and the lever, I tested the tightening system with a store bought screw.
I then drilled and tapped a pice of brass to a M4 thread, and cut the screw shorter to have a small piece of threaded rod. After driving the threaded rod on the new brass nut, I drilled a 1.5mm hole across the nut and the threaded rod, and then drove a 1.5mm steel pin in to lock the nut and threaded rod together. I then filed the brass to a hexagonal shape to give it more grip, and sanded it to 400 grit.