When fettling a plane
for the first time a lot of attention is usually
paid to the iron, or blade, and rightfully so.
It's because no matter what else you do to
a plane if the iron is not sharp the plane wonít function at its
The next most important part in the process is
the cap iron, commonly known as the chip breaker.
This part must fit the back of the iron
perfectly with absolutely no gaps between it and the iron. The
slightest gap between the back of the iron and the cap iron will
catch a shaving eventually choking the plane mouth. The next
operation on the cap iron is honing the face where it meets the
back of the iron. Until recently I always honed this angle to 45
degrees, but I have learned differently, and in a moment I will
share what I have learned.
When I first began using hand planes I
experimented with mouth openings and cap iron settings. It is
widely accepted that to avoid tear out we need a very tight
mouth and I tried this. What I found was that if you have a
tight mouth and a tightly set cap iron you will inevitably
experience choking. So either the cap iron setting or the mouth
opening had to be changed. After trying a tight mouth with a
wide cap iron setting I tried a wide mouth with a tight set cap
iron and that almost eliminated tear out. Then I was introduced
to this video. If you havenít already seen this video I advise
you to watch it.
This video confirmed what I had already learned.
A tight mouth is not necessary for tear out free planing on all
but the most difficult woods. The majority of our planing can be
accomplished virtually tear out free using a sharp blade and a
properly setup cap iron with an open mouth. No more adjusting
the mouth every time you change the thickness of your shaving,
which with a Bailey style plane can be time-consuming.
This is the method I use to hone the front face
of the cap iron to 80 degrees. The steel block is only to hold
up the block for the photograph.
A close shot showing the cap iron face on the
Here you can see the clearance in the 80
for the bend in the cap iron.