Friday, July 13, 2018

Coffin Smoothing Plane Build - Part 2

Part 1 of this build showed the general construction of the plane body.  This post will highlight some shaping details and the work required to get the plane cutting smoothly.

But first, I couldn't help but try the plane after it was glued up.
First shavings - test cuts were OK
After the glue had set, I cut off the extra length at each end - the final overall length is 7 1/2".  Then I did some typical shaping of a coffin smoothing plane body.
The plane body shaped
The back end was rounded over using chisel and rasp and the sides were curved using a chisel and plane to make the coffin shape.  The upper 3/8" of each side was chamfered, and the chamfer was extended half way down the front and back ends of the sides.

One detail that I see on most wooden bench planes is the "eye".  That is the little "teardrop" chamfer shape on both sides where the throat meets the top of the plane body.  I never knew what the purpose of this feature was, but now I know it is not just decorative.  Using wooden planes requires a lot of reaching the fingers in the throat to pull out shavings.  Without these "eyes", the sharp edge of the throat would scrape the fingers as you pull out shavings.

The final step for the body was to flatten the bottom.  I did this first with a metal-body smoothing plane and then rubbed the sole on sandpaper glued to plate glass.  Next I completed the shaping of the wedge.
The completed wedge shape
Boiled linseed oil was used for a finish - three coats over three days.

When I tried the plane out, I was getting some "chatter" and the surface left by the plane clearly showed the problem.
Chatter shows up easily in an enlarged photo - not sure if you'll see it here
Chatter plainly seen in this edge cut
I skewed the iron a little so that the right side of the iron receded into the plane body.  This resulted in a shaving that clearly showed chatter problems.
A face grain shaving showing chatter issues
I tried skewing the plane and the performance improved, but did not eliminate the chatter.  I googled the problem and found a video that Bob Rosaieski had done on how to diagnose and fix this problem on wooden planes.  The link is here.  In the video, Bob coats the back of the iron with soot from a burning candle.  Then he assembles the plane with iron and wedge, taps the back end of the iron to move it slightly and looks to see where the soot has been left on the bed.

This worked perfectly for me.  It clearly showed where the high spots were - I had an area on one side of the mouth where the iron was not touching the bed.  After paring away the high spots (this took several iterations with the candle and paring), I got the bed flat and the iron started cutting properly.

Here she is, all done and fettled.  The bed angle is 45* and the breast angle is 60* (don't know why, but my keyboard shortcut for the degree symbol of <alt>248 doesn't work anymore).  The wedge angle is 10 or 12*, I forget which.  The plane body is 2 9/16" wide at its widest point and is about 2 5/8" tall.
Glamour shot
I don't know at this point whether this plane will become a regular user, but at the very least it is proof-of-concept about this method of plane building.  I hope to build a wooden jack plane sometime in the not-too-distant future and possibly even a try plane.  Gotta find some irons that are more appropriate for that, though - the iron in this smoother is a thin Millers Falls iron from a metal smoothing plane.

If you'd care to comment, I'd love to know about your experiences in building similar planes.

Friday, July 6, 2018

Coffin Smoothing Plane Build - Part 1

This might be due to reading some of Joshua Klein's stuff, but I've been interested in wooden bench planes lately.  I've never owned one, nor have I had access to one, so I've never used one.  Richard McGuire did a great video series on making a wooden jack plane.  But I don't care for the Krenov-type planes (like Richard's) that use a cross-pin to wedge the iron.  I'd much rather have an abutment like traditional wooden bench planes.  I did some internet research on wooden bench plane designs, though it sure would have been nice to have a couple of these planes to help with some details.  A few weeks ago I made my first attempt at a wooden smoothing plane
Sketchup model (without shaping) of a coffin smoother
I started off using Sketchup to rough out a design.  Mine is a three-piece construction, but it's different from other laminated designs that I've seen.  In mine, the sides start out 1/2" thick and I cut the 1/4" deep abutments into them before gluing the whole thing together.
Side pieces showing abutments cut out
For this plane, I'm using a standard 2" wide smoothing plane iron from a metal Millers Falls plane.  The center portion of the plane body is 1 9/16" wide.  With the two 1/4" abutments, this allows the iron a little wiggle room for lateral adjustability.

I made my pieces a couple inches longer than final length so that I could drill holes at the ends and insert dowels to keep the parts aligned.  The extra length was cut off later.  I started by cutting the bed angle of 45° and a breast angle of 60°.
Scrap triangle partially reinserted into the hole it came from
Marking the rear extent of the abutment with the plane dry-assembled
For the forward extent of the abutment, I made a temporary narrow wedge (too narrow to be used in the final plane) to mark the line.
Temporary wedge in place for marking forward extent of abutment
(The drill bit is just a spacer and there is a small wedge forcing the temporary wedge to the right side of the plane)
In the picture above, the drill bit is simply a spacer to keep the wedge from going too far down into the throat.  I also have a very small wedge forcing the temporary wedge to the right side of the plane.  This allowed me to make a knife line to mark the forward aspect of the abutment.  I took great care in making the temporary wedge - I wanted the taper to be exactly the same on the left and right so the abutment lines would be accurate.

With the abutment lines knifed in, I sawed and routed the abutment, and cleaned up the saw cuts with a chisel.
A first dry-fit with the final wedge

Managed to get a nice tight fit of the wedge (with iron installed)
Then I did more shaping of the lower portion of the wedge
Here's something I was not sure how to handle: in the area where the pointy prongs of the wedge recede into the abutment, the wall just forward of the abutment is full width and creates a void where shavings could get trapped.
Can you see the void area at bottom of wedge prongs?
To deal with this, I chiseled the side wall to match the prongs.
Left side with area forward of the wedge prong relieved
Plane reassembled and a much smoother transition
With the throat complete I glued up the plane.  The intent was that the dowels would keep the two sides and the center pieces perfectly aligned.  There was a tiny bit of wiggle room and it didn't come out perfectly, but didn't require too much fettling to work OK.
The glue-up
Next time I'll write about the shaping details and what was required to get the plane cutting properly.