The most important tasks in building a wood-bodied plane are cutting the bed to an accurate angle and setting the mouth. With the bed and ramp blocks cut, it’s time to put everything in position, set the mouth and glue-up the plane. After this next set of steps, our smoother plane will start looking like an actual plane!
Assembling the pieces of the plane
1. Route groove for blade screw
This is a bevel down plane, so the screw that holds the blade and chipbreaker together protrudes on the blade side. Since the blade side is what registers against the bed of the plane, there needs to be a groove in the bed to accommodate the screw. The groove can’t go all the way through the bed of the plane because there needs to be wood toward the sole to support the blade. This calls for a stopped groove, which is best executed on the router table. A ¾ straight router bit is perfect for this operation, making the groove slightly wider than the screw so everything fits together easily. I don’t have a ¾" straight bit, so I made the groove with two passes of a ½" bit overlapping each other. The groove needs to be slightly more than ¼" deep.
First, mark the place on the bed block where the groove should end. To find the location, put the blade and chipbreaker against the bed and move them down to where they would be in use. Mark the location of the lowest part of the screw, then make another mark a bit lower. Use the lower mark as your stopping point. Use the triangle piece that came from the body of the plane as the stop block, which will ensure you won’t cut all the way through the bed block.
2. Position the blocks to set the mouth
With the groove cut, the blocks are ready to be positioned. The location of the blocks is critical for how the plane will perform. Since this is a smoother plane, it should only take light shavings. Because of that, the mouth needs to be set tightly — with just a slight opening.
Lots of plane makers position the ramp block so that they have to file off a bit to establish a tight opening. I’m not confident in doing this accurately enough with a file, so I like to set a tight mouth by positioning the blocks.
Set the ramp block aside for the moment and start with the bed block. Put the bed block and cheeks on a flat surface and carefully clamp them together, checking to see that your registration marks line up exactly. To maintain these positions precisely, I drilled countersunk holes in the cheeks so they can be screwed to the plane blocks. The traditional method is to use dowels, but I find that screws are more precise and provide a bit of clamping power during the glue up. Use two screws for each block on each side of the plane, for a total of eight screws. Screw the cheeks to the bed block on both sides.
3. Set the ramp block
I came up with a little trick to set the ramp block so that it establishes a tight mouth for the plane. Tape a business card (or in my case a coffee shop frequent buyer card) to the ramp block so that it touches all the way to the bottom.
Put the blade and chipbreaker against the bed where they will be in use. Now move the ramp block between the cheeks until the business card just touches the plane blade. Clamp it in place and drill countersunk holes through the cheeks for more screws.
This position will establish a fine mouth setting and ensure that the mouth is perfectly parallel to the edge of the blade. Now that everything is temporarily attached, use a pencil to draw the block angles onto the cheeks inside the plane. This will show where to apply glue.
4. Locate the cross pin
In his original planes, Krenov made cross pins with round tenons on the ends and a flat surface that registered against the chipbreaker. I chose to use dowels because they work well and reduce the number of steps in making the plane.
The next step is to locate the cross pin, which is a ½" diameter hardwood dowel. Start by drawing a 50-degree angle on the outside of the cheek starting at the tip of where the bed block begins. Use an engineer’s square to draw a perpendicular line on the outside of each of the cheeks also starting at this point. Using a combination square set to 1 ¼", make a another line parallel to the sole. Do this on both cheeks with the same setting. This marks the centers of the cross pin holes. Unscrew the plane and take it apart. Drill ½" diameter holes with a drill press at the intersection of the lines.
5. Assemble and glue up plane
To keep everything square and flat, I placed a piece of wax paper on my table saw for the glue up. Apply glue, going right up to the traced block lines, then add the screws, checking to see that everything is lining up perfectly. Tighten the screws and use a few clamps with clamp blocks to hold everything together. Let the glue set up for half an hour or so, then scrape it off the ramp and bed blocks inside the plane.
Once the glue dries, it’s time to make the wedge, true the sole and then shape the body of the plane. This smoother will be making fine shavings in no time.