Thursday, March 26, 2020

Wooden Plane Throat Geometry

I've been thinking for a couple weeks about how to write this post.  There are certain aspects of throat geometry that are very difficult to photograph, and without decent pictures it's tough to describe.  So I'm going to try this with a combination of pictures and Sketchup images.

I'm not an expert on wooden planes.  Most of the woodies I've used are ones that I've made.  I know there are MANY different wooden plane geometries out there.  I'll write about one aspect that you may not know about until you've studied these planes.

To do this I'll first show in sketches a sequence in making a wooden plane.
First, the bed, breast, wear and abutment lines are laid out on the plane blank (toe at left)
... and those lines are continued across the top (and also the sole)
Note that there are two sets of lines going toe-to-heel on the top of the plane blank.  (Those lines should also be drawn on the sole within the mouth area, but I had not done that when I exported the first pic above.)  The inner lines mark the innermost extent of the wedge abutments.  The outer lines mark the depth of the abutment recesses and, on the sole, they mark the overall width of the mouth.  One method of constructing a wooden plane is to excavate to the inner lines first, and that would look like this:
Primary excavation
And here's a birds-eye view
Currently, the mouth is not wide enough to fit the iron.  Then material is removed for the abutment recesses.
Abutment recesses formed
You'll notice that these recesses extend all the way to the sole.  The lines laid out on the sole to mark the lateral extents of the mouth guide the plane maker to end up with flat abutment recess walls.  The total width of the recess for the double iron and wedge is the same as the width of the mouth.  This is about 1/16" greater than the width of the iron, and that allows a little wiggle room for the iron to adjust its edge parallel to the sole.

To aid in removing shavings from the throat, some wood is chiseled away forward of the abutments.
Throat widened towards front
The throat is widened nearer the front of the plane.  The abutment line connecting locations 2 and 3 is unchanged.  The location at "1" is taken down to the same depth as the abutment recess.  Later, the "eyes" are carved into the edge that joins locations 1 and 2.  I can't do that with Sketchup, so I'll show a real pic.
Arrows show locations of the "eyes"
OK, now I'll introduce the wedge (shown in red) and the double iron to this picture.
Wedge and irons added to the picture
And here is a zoomed-in view of the area near the "3"
The (initially too long) wedge is cut off at the location where the cap-iron starts curving down to meet the iron.  Then the two lower ends of the wedge are tapered.  This helps to steer shavings towards the center of the plane as it cuts.  The taper begins just to the right of the number "3" in the above picture.
You can see the tapered ends better in this solo sketch of a wedge
As it stands in the pics above, the area of the plane body near the "3" could cause shavings to get jammed between the abutment and the wedge, so some material needs to be removed, just like the tapered end of the wedge.  I've tried to draw this in Sketchup, but it's tough due to many odd angles.  Hopefully you get the gist.
Some material below the "3" removed to match the taper of the wedge fork
The combination of the taper on the wedge fork and the taper on that part of the plane body will force shavings to the center of the throat.  Any discrepancies in this area - places where the tapers don't mate well - are places where shavings could get caught and cause a jam when using the plane.

In the following picture, hopefully you can see the area that was removed just forward of the tapered part of the end of the wedge.
The shadowy area down in the throat is what I'm describing
This is just one seemingly minor aspect of wooden plane design and fabrication that is not readily apparent to the novice plane user/builder.  But it is critical to the performance of the plane.  As I've found out, it can be tough to get a chisel in there to remove that material and create a smooth transition between wedge taper and plane body.

Next week I'll post about making two wooden smoothing planes - a prototype and the real deal.

Thursday, March 19, 2020

Rehab of J. Pearce Wooden Smooth Plane

Last week I wrote about the old J. Pearce wooden smoothing plane I got at a tool auction.  Here is my summary of what I did to refurbish it.  First was the 2" wide iron, which was in pretty rough shape.
The Chapin Stephens Co., Pine Meadow, Conn., U.S.A.
Iron and cap-iron
The iron and cap-iron were both fairly rusty with a lot of pitting.  After getting the superficial rust off with sandpaper, I let them sit overnight in a citric acid bath, then sanded again to remove the debris.  This revealed the extent of pitting I was going to have to deal with.
Pitting on the flat side of the iron
This is after rubbing on coarse sandpaper and extra coarse diamond plate
The depth of some of the pitting really shows after removing some surface metal.  And unfortunately some deep pits are right up by the cutting edge.  I worked this iron for hours (literally), coming back to it after taking breaks to do other things.  I worked both vertically (with the "grain") and horizontally on the abrasives.  Making a little holder that allowed me to put pressure right over the iron when rubbing on the abrasives really helped.  Eventually I got down to bare metal.
Just a few minor pits left near the very edge
When I was satisfied that the pitting was removed from the back, I went through the finer grits and got a nice polished surface.
Mirror finish on the back
Then I ground a new 25° bevel ...
(Note the laminated nature of this iron is clearly evident)
... and honed a secondary bevel at 30°
The cap-iron was in fairly rough shape as well.  Fortunately it didn't need too much work to get the leading edge sharp and mating well with the back of the iron.
Underside of cap-iron showing abrasive wearing at both corners, hollow in middle
And with the iron sharp, I couldn't resist trying to make a shaving.
First shavings
Before taking those shavings, I had flattened the bottom, which was quite uneven.  Then I took a rag soaked in turpentine to clean up the body and wedge.  This made a nice difference while keeping the patina.
The rag shows some of the grunge that came off the body
After letting the wood dry, I squeezed some glue into the large crack where the right side abutment meets the bed and clamped it up.  This seems to be holding so far.
Showing the location of the crack
The glued up crack from outside
A day later I gave it a soaking in BLO, wiping off after about 20 minutes and repeated this procedure the next day.  The wood sucked up the oil like there was no tomorrow!

And thar' she blows!  The plane took a nice shaving from some poplar and it is looking good.
All done - taking a nice, fine shaving
I don't think this plane will become a regular user, however.  The mouth is a bit too big, so I don't know how it will perform on some woods that are tougher than this poplar.
Opening between iron's edge and front of mouth is about 1/8"
I know I could glue in a patch to close up the mouth, but I didn't want to do that on this plane.  Maybe later, though.  After this was finished, I made my own version of the plane and I'll post about that soon.

Until then, stay healthy and safe ...

Thursday, March 12, 2020

J. Pearce Wooden Smoothing Plane

At a recent tool auction during a meeting of my local tool collectors organization, I bid on and won a box of four wooden planes.  One of them was this little coffin smoother, stamped J. Pearce, of New York.
Pearce Smoother
The toe, showing "maker" name and model no. 108
From what information I could find on the internet, J. Pearce was not a manufacturer but was a hardware store brand name used by H. Chapin.  The iron is stamped "The Chapin Stephens Co."  Other J. Pearce planes I've seen on internet sites have had Chapin Stephens irons, so I suspect this iron is original to the plane.  Some information on a Sawmill Creek thread indicates the plane probably dates from 1901-1929.

Here are some details:

Length: 8"
Width: 2 5/8" at mouth, ~ 1 13/16" at toe, ~ 1 1/2" at heel
Height: 2 3/8" (likely it was 2 1/2" or thereabouts when new)
Toe to bed line distance: 2 3/4"
Bed angle: ~ 47°
Breast angle: ~ 101° (though upper inch or so has been widened with poorly executed chiseling)
Wear angle: no wear - the breast goes all the way to the mouth opening

Strike button diameter: 11/16"
Strike button location: centered laterally, 7/8" from toe (roughly centered between toe and throat)

Wedge dimensions: 4 7/8" long x 2 1/16" wide x ~11/16" thick

Iron mfg: The Chapin Stephens Co., Pine Meadow, Conn, U.S.A.
Iron width: 2" (at cutting edge; 1/32" narrower at back end)
Iron length: 7 3/4"
Iron taper: 7/32" thick behind bevel to 3/32" at rear
Iron construction: steel laminated to iron base

Some pictures of its condition follow.
The heel had some large checks, the lower one caused the sole to be way out of flat
I read that this line of planes was mass-produced and a "second line" of Chapin's planes.  It may have used wood that was not top quality or not properly dried.  The billet this plane came from was not quartersawn, but riftsawn, with center of the tree to the upper right corner of the plane (looking from the rear).
There is a large crack on the right side where abutment recess meets rear plane body
With wedge and iron removed, you can see that crack from the inside
Picture from behind looking forward - note how asymmetrical the abutments are.
You can also see the hack job on the breast surface.
Whether that hack job is evidence of the "second line" status of these planes or was a user modification is unknown.

Finally, note how the abutment recesses have been hollowed out, presumably by thousands of removals and insertions of the iron.
See the gap under the ruler?  Both sides showed similar wear.
Just a couple notes about the iron and cap-iron.  There was a fair amount of rust and corrosion on the iron and I'll get into that next time.
Bevel side of iron
The Chapin Stephens Co., Pine Meadow, Conn., U.S.A.
Iron and cap-iron in profile
The threaded hole of the cap-iron had a raised, threaded portion on the side that mates with the iron.  It seems to me I've seen a raised brass area on the opposite side of old cap irons to increase the thread length.  Perhaps this one is a newer design.  It fits within the iron's slot and is not raised much, so it doesn't get in the way of tightening the screw.
Cap-iron below the iron, with raised threaded portion sticking into slot of the iron
Next time I'll write about cleaning and refurbishing the plane.  I've also built my own version of the plane and that will be the subject of another post.

Thursday, March 5, 2020

Desktop Bookshelf, Part 2

In part 1 of this build, I mentioned there were two tricky things to deal with.  The first had to do with marking the mortises within the dadoes that would house the small tenons of the shelves.  I wrote about that in the previous post.

The second tricky thing was to mark the shoulder line of those short tenons.  This may not sound so tough, but here's the thing.  In the beginning of this build, I ganged the two shelves and three back rails together to mark their common shoulder lines.
Bottom shelf, top shelf and three rails ganged together for marking
For the shelves, this marked the shoulder line of the notch that allows the front of the shelf to sit outside the stopped dado.  I'm not sure of a better way to describe this, so I'll show it in pictures.
Lower shelf extends past front of side
With lower shelf removed, you can see the 3/8" deep stopped dado (and three mortises)
With shelf shown and side removed, you see the notch at front of the shelf
that fits over the end of the stopped dado
Here's a closer pic.  This is the shoulder line that I marked when
 shelves and back rails were ganged together.
But the shoulder line at the base of the short tenons was the one that was hard to figure out how to mark.  I tried using the actual pieces to mark it, but it was tough to hold the parts in the right position.
Holding the shelf backwards (relative to the side into which it fits), with the first shoulder line sitting flush with the side. 
In this closer view, I'm marking the tenon shoulder line with a pencil
I would have preferred to mark this with a knife, but I found it hard to get a knife in there so that it would be positioned correctly.  This worked out OK, though it was not perfect and the joints needed a bit of fettling.

Once I determined the location of that shoulder line and squared it around the shelf, I placed the shelf into the dado and marked the tenons through the mortise holes.  Then I cut away the parts that weren't tenons, down to that shoulder line.  The shelf tenons ended up looking like this:
Upper shelf tenons and front notch
The three back rails were dovetailed into the sides, a half inch between rails, and the lot of them centered between upper and lower shelf.
Back rails dovetailed into the back edge of the sides
I shaped the sides, cutting away a curve that started halfway (9") up the front and ending halfway (5") back on the top.  After putting a round-over on the front edges of the shelves, a dry fit made it look like something.
Dry fit looks good
I wanted to reinforce the small tenons, so I sawed a kerf in them and glued in small wedges during the overall glue-up.  As it turns out, I don't think the wedges will help much, if at all, because there was too much wood either side of the kerf to bend easily and tighten against the mortise walls when the wedges were driven in.
Glued in wedges to strengthen the joints
Clamping the bookshelf to clean up the glued joints was a tricky matter.  I used the method where a couple of battens are clamped to the workbench, overhanging the front edge of the bench.  The bookshelf is suspended on the battens.  This worked pretty well - first time I ever tried this method.
Using battens to hold the bookshelf for joint flushing
Then used chisels and a plane to pare away the proud tenons
Finally, I glued a piece to the rear of the top shelf, then gave it a couple coats of shellac and put it in its final home.
Gluing on the "upstand"
A couple coats of shellac gave it a nice golden appearance.
And here she is loaded up with my woodworking books and an old woodie
It was a good, relatively quick project.  Now it's on to other things.