Wooden Jack Plane Build - Prototype #1

I've been wanting to make wooden jack and try planes for quite a while.  A few months ago I bought the irons for them and finally I'm getting around to the build.  But because I don't want to mess it up, prototypes were in order.

Before I begin, I'd like to credit Richard McGuire, whose jack plane build videos really helped me, and Caleb James, whose published free plans for a wooden jack also helped a great deal.  I don't have plane floats, so like Richard's plane build (and unlike Caleb's), I'm using a three-piece glue-up for my design.  And like Caleb's plane (and unlike Richard's) I'm using abutments to wedge the iron rather than using a cross-bar - I much prefer abutments.  I built a wooden smoother this way last year and it turned out pretty good.  Those blog entries are here and here.

The coffin smoother in red and white oak

The first prototype jack plane is in pine.  I started with two 15 1/4" pieces of 2x lumber glued together.  After squaring it up to about 2 5/8" tall (thick) and about 3 1/4" wide, I sawed off 1/2" thick pieces from each side, then planed the sawn surfaces to get me sides that were 1/2" thick and the main body that was 1 15/16" thick.

Two sides and main body

The iron for this plane is just shy of 2 1/4" wide.  When I add 3/16" recesses to the sides (they form the abutments) to the 1 15/16" main body, I get an area that is a little more than 1/16" wider than the iron.

On the sole of the main body blank, I measured 5 1/2" from the toe to mark the back of the mouth.  Then on the sides of the blank I drew a 45° bed angle and a 60° breast angle from that spot.

Main body lines laid out

Then cut out the triangle and planed perfectly square the bed and breast

It made sense here to create a recess for the cap-iron screw.
I used chisels and a router plane

As it turns out, the slot in the iron (and hence the cap-iron screw) was not perfectly centered, but was slightly off and I failed to take this into account.  I later had to widen the recess to accommodate this.

On the fore part of the main body I added a small wear angle (bottom left)

To start creating the abutment recess on the sides, I marked a line directly from the main body bed.  I did this rather than simply marking a 45° line on the side with a combination square in case there was any deviation from the 45° bed angle after having planed it.

Marking the rear abutment recess line

Next was to figure out where to put the front abutment recess lines.  I started on paper and found that this double iron forms an angle of about 1-2° (in the opposite direction as the wedge angle).

Worked out some angles on paper with the actual iron and cap-iron

I wanted a wedge with about a 10° angle, so the iron/cap-iron and wedge combined would be about 8-9°.  I created a temporary 1 15/16" wide, 10° wedge, placed the iron/cap-iron and wedge in the plane and marked a line on the side.

Marking the forward aspect of the wedge abutment recess

Then I used a bevel gauge to make a knife line at the penciled line, sawed the shoulders of the recesses to a depth of 3/16" and removed the waste with chisels and router plane.

Far side is being held away from main body, near side is in proper placement

And here are the three parts placed together

 Then while holding the plane together, I inserted the iron and looked at the sole.

When I moved the fore part of the plane to a location that would give a reasonably sized mouth
I got the funny offsets that you see here.  I dealt with that later.

Then it was time to glue up.  I lined up the parts as accurately as I could, turned the plane upside down and placed packing tape across the bottom to hold things in the right position while gluing up.

Then turned right-side up and added glue to the sides

After clamping and allowing to dry, I cleaned up the surfaces

As for that discrepancy on the sole, ...

... I chiseled the wear back to line up with the sides

But this created a mouth quite a bit larger than I wanted

I didn't get any good pics of this, but I made a wedge out of poplar.  After sharpening the iron I took some shavings and the prototype worked nicely.

First shavings from a scrap of pine

This prototype works, but is not optimal.  Next time I'll write about what I changed to tighten the mouth.