I, too, have an old #4 smoothing plane that my grandfather gave me.
Unlike some of the other tools I inherited from him, this plane is
wholly unburdened by any pedigree—or even a manufacturer's name. My
grandfather bought it in Calcutta when I was eleven years old. I knew
nothing about planes, but I used it happily for a few years. Then I
discovered computers, and the plane went into a box.
Now, nearly three decades later, I need a plane again.
This is my story of restoring an old plane to the point where I could
use it. If there's anything to take away from this article, it is that,
with sufficient effort, even a poorly-manufactured plane may eventually
be made to work well. Was it worth the effort? Well, I have a working
plane now. I know my grandfather would have been pleased.
Resources
As a first approximation, restoring old tools consists of taking them
apart and rubbing the parts against a variety of abrasive substances
(sometimes for hours) to remove rust and reshape them until they look
and work better.
To learn about plane restoration, I recommend starting with this
video tutorial by Paul Sellers,
whose focus is to quickly restore a plane to working order. Here's a
diagram of bench plane parts;
the rest of this article assumes you are familiar with these terms.
General cleanup
The plane wasn't in terrible condition to begin with. Once I wiped off
the dust with an oily rag, it took only a few minutes to get rid of a
few spots of surface rust on the body with sandpaper. There was some
rust on the plane iron too, which I sanded off after soaking briefly
in a dilute vinegar solution.
Plane iron
There were two things wrong with the plane iron: it was not very good,
and it had been sharpened many times by an eleven-year-old me.
Fixing the damage I had done in the past was not as difficult as I had
feared. The bevel was uneven and rounded, there were nicks in the
cutting edge, and it wasn't very sharp. Thanks to
my diamond sharpening plates, it was
just a matter of time and practice to grind and polish a new bevel,
relieve the corners, and put a fine camber on the cutting edge.
The back of the iron was nowhere near flat, and the steel was very hard.
It took several sessions on the extra-coarse plate to flatten the (last
few centimetres of the) back, leaving only two low spots on the corners
where the grinding wheel in the factory must have dug in. Removing them
would have meant removing a lot of steel, so I stopped there. I did try
tapping the back of the iron with a hammer to create a low spot in the
centre, so that only the edges would need to be ground flat, but the
steel was so hard that it had no noticeable effect.
(Normal sharpening during use subsequently removed enough steel from the
cutting edge that the low spots on the back are no longer apparent.)
The leading edge of the cap iron fit poorly against the back of the
plane iron. I ground it flat on the diamond plates to eliminate the
gaps, and lightly polished the upper surface. I also filed off a sharp
exposed point on the thread of the captive screw, which always managed
to find its way under my fingernail when I was reattaching the cap iron
to the sharpened plane iron.
Lever cap
The lever cap was so poorly machined that it gets its own section here.
The cam on the lever was shaped wrong, so that it couldn't be released
at all once it was locked down, and I had to loosen the screw on the
body to remove the lever cap every time I wanted to sharpen the plane
iron. Worse still, the screw didn't hold the lever cap securely—the cap
would slide around as I tightened the screw, and end up crooked or
off-centred. Even after the screw was tight, the lever cap would
sometimes slip off the correct position and come loose.
I flattened the leading edge of the lever cap to improve contact with
the cap iron. I tried to file the cam to the correct shape, but I didn't
get it right, because it wasn't possible to remove the cam, and access
was limited by the flat spring and the body of the lever cap. The best I
could do was to make it work "backwards": to lock down in the raised
position, and release when lowered. This is rather annoying, but it does
seem to work.
As for the other problem, the only solution I have is to hold down the
cap firmly when tightening the screw. With the modified cam, at least I
don't always need a screwdriver handy to remove the plane iron
for sharpening.
The right answer may be to find a used lever cap on eBay.
Body and sole
The sole of the plane was not flat. I put some #150 grit silicon carbide
paper on a sheet of float glass and rubbed the plane (with the blade on,
but retracted) across it a few times to identify low spots. I had to use
the extra coarse diamond plate and #60 grit belt sander paper to flatten
the sole just enough to bring heel, toe, throat, and edges into level. I
then worked my way back up the grits to polish out the scratches. I also
relieved the edges of the sole and heel on the sandpaper.
The face of the frog was not flat. I used #150 grit paper on float glass
to knock down some of the high spots, but decided it wasn't worth it to
pursue a couple of low spots along the edge. I cleaned up the contact
surfaces along the bottom of the frog and on the body too.
The throat opening was not finished evenly, and it had some nicks in it.
I used a flat file to remove some of the irregularities, but decided not
to remove as much steel as it would take to make the throat straight and
square and work out all the nicks. The opening was quite wide to begin
with, and the remaining nicks seemed to not matter much in practice.
The wooden parts (tote and front knob) were in good condition, with no
cracks or surface damage, so I didn't need to do anything to them.
Things I didn't fix
The sides of the body were not square to the sole. Sandpaper on float
glass would have fixed it, but my fingers were threatening to fall off
after flattening the sole and the frog, so I didn't bother. I may need
to revisit this once I start using the plane on a shooting board.
There's no good way to close down the throat. The opening was wide to
begin with, and I had to file it down further to remove irregularities.
Advancing the frog causes chatter because the contact points between the
frog and body are sketchy. Applying enough abrasives could, in theory,
solve this problem, but it's not worth it.
The adjustment knob used to set the depth of cut is a bit awkward to
use, partly because the lever cap needs to be cinched down so tightly.
Another oddity is that it is on a screw with a normal thread; I believe
it's usually reversed, so that rotating the knob clockwise advances the
blade. On my plane, it's the other way around. Nothing to do about that
but get used to it.
The lateral adjustment lever just doesn't work well. The mechanism has a
lot of slop, isn't quite centred, and goes further on one side than the
other. I don't know how to fix that.
Conclusion
My plane will never compete with the old Stanley or new Lie-Nielsen #4s
of this world, but it does work. I can set it finely enough to take
full-width shavings a few hundredths of a millimeter thick, leaving a
mirror-smooth finish. Occasionally, I can even plane knotty cypress
against the grain without tearing out or leaving gouge marks on the
surface. That's far beyond anything I expected from it.
Is it a plane I will use forever? No. But it's a plane I will always
remember, and that makes it a pretty special gift.