Friday, June 16, 2017

Rehab a Side Bead Plane - Part 3, Working the Iron

Part 1 of this series was about cleaning up the plane and fixing the boxing.
Part 2 of this series dealt with reshaping the profile.


This post is about working on the iron.  If you're shaping (not sharpening) your first molding plane iron and think you've gotten the shape right, you're probably wrong.  I don't mean to sound like a jerk. It's just that you really need to keep at it to get it right.  During this rehab, I've learned a lot about how well the iron should match the plane's profile.  If it is off just a little bit, it's not going to work as well as it could.

First, let's look at how to remove the iron from the plane.  This was not obvious to me at the start.  I forget where I read this technique, but it really works.
Hold the plane with first finger in the wedge's recessed area
Then give the rear end a good smack with a wooden mallet and the iron and wedge will come loose
Try not to hit the whole of the back end - the mallet should hit the curved upper portion of the back end.  You don't want to risk chipping a section off the sole. Previous owners apparently used metal hammers that left large bruises in the heel end.  Wood is a much better choice.

You can also tap the back end of the iron with a metal hammer (I'd use brass if I had it) to push the iron forward until it comes loose.  But the iron on this plane only barely extends further than the wedge, so I risk damaging the wedge with the hammer.

Here's a sketch of the profile of a side bead plane.  The plane is upside down, with the front end towards you (like it is when you sight down the sole to check the projection of the iron).  The iron is shown as a gray color.
An even 1/64" all around
In the above sketch, there is an even 1/64" reveal of the iron all around the profile.  On the left side, the iron will leave a small rabbet on the outside of the profile that it cuts.  In Bill Anderson's article, he mentions that the reveal of the iron should taper out on the left side.
Iron's reveal tapers into the fence
Bill's article doesn't mention this, but I think the right side of the iron should also taper into the quirk, like in the following sketch.
Both sides of the curve of the iron recede into the plane's profile
If you think about how the iron cuts, the deepest part of the bead profile and the quirk are the only parts of the iron that cut like we normally think a plane iron cuts.  That is, those parts of the iron are roughly perpendicular to the surface being planed, so they can make a nice shaving.  The sides of the bead profile are angled relative to the surface being cut and they perform more of a scraping action.

It's really tough to get decent pictures of the iron when it's in the plane, but I tried anyway.  In the following pics, the front end of the plane is very blurry, as I've tried to get the iron in focus.  And since I'm taking these pictures from a slight angle relative to the sole, it will look like there is a little bit more iron protruding than what is actually presented to the wood.
Left side recedes into the fence too early and also too abruptly, curve shape is a little bumpy
I first tried shaping with sandpaper wrapped around small screwdrivers, but found that to be far too slow.
Not the optimal equipment for shaping iron
I had ordered some chainsaw files of different diameters and these did the rough shaping far better.  It turns out that the part of the iron hidden in the fence had been shaped too aggressively (by someone else) and I couldn't get the shape along the left side to taper into the fence like I wanted it.

I went through at least 20 iterations of shaping and checking, so I got good at installing and removing the iron.  I thought the shape was getting better - and it was - but it was only marginally better.
Still too heavy a cut on bottom left, not enough taper into fence
A little better, but still not where it should be
When the iron recedes into the fence too soon, you get this result.
Arrow points to a visible line between curve and flat - should be seamless
Instead of a nice rounded curve on the outside of your workpiece, this leaves a distinct line where the plane left off and the flat part of the workpiece begins.  It's easy enough to sand that line away or hit it with a block plane, but you shouldn't need to.  I finally realized that the part of the iron hidden by the fence was too far into the fence and I would have had to remove about another 1/8" of iron to get it right.  I had already removed 1/8" or more of the iron with all the shaping attempts, so I called it "good enough" for this plane.  I had taken so much off the iron that I had to take a shaving or three off the wedge - in effect, shortening it so the iron was still extended further than the wedge.

I had a much sweeter result for the second beading plane, a 1/4" beader (though it had "5/16" stamped on back) from A. C. Bartlett's Ohio Planes.
My second beading plane to rehab
I believe there used to be a "16" under the "5" and the "--"
You can see the effects of several metal hammer blows.
After just a few rounds of shaping, the iron looked like this:
This is exactly what I'm looking for
And that gave me the beautiful profile I wanted on a test piece
Sharpening:

After the shape couldn't be improved any further, I needed to sharpen.  All the shaping was done with files at an angle of about 25°.  The sharpening was done at about 30°, so only a small amount of metal needed to be removed to get a sharp edge.

I made a jig for sharpening molding plane irons, based on the one Ralph uses.
Molding plane iron sharpening jig
To use sandpaper to sharpen, I needed a stiff rod with diameter just shy of the bead profile.  I tried small screwdrivers first, but one thing that worked very well was my burnisher.
Burnisher used for sharpening with sandpaper

End view of burnisher
The oblong cross sectional shape of the burnisher was great for wrapping sandpaper around and sharpening the irons.  Even though the iron cuts a round profile, the shape that needs to be sharpened is actually oval.  I went through 400, 600, 1000 and 1500 grit papers, and stropped it with a piece of leather with polishing compound on it.
Leather "strop" for the shaped bevel

Well, that's about it for the rehab of the H. L. James beading plane.  I'm off to work on the others.
Ready for another hundred years of use