There has been much renewed interest in the use of the chipbreaker in tuning a plane. For some decades the view prevailed that the chipbreaker simply supported or stiffened the blade. Indeed, that was the dominating belief when I reviewed the LN chipbreaker when it was first released some 10 years ago. Today the chipbreaker is seen to be an important factor when tuning a smoother to reduce tearout on interlocked grain.
This is not a new discovery – just ignored for some decades by popular woodworking writers, and the new woodworkers that followed them.
The research of Professors Kato and Kawai in Japan brought fresh evidence that a chipbreaker placed close to the edge of the blade changed the manner in which the wood chip was formed. The effect is to create a Type II chip, which is what occurs with a high cutting angle. Tearout is reduced or eliminated.
When the chipbreaker is set this way, the shaving is deflected by the leading edge and, instead of curling back over the mouth, is pushed upwards.
A link to the
video of Kato and Kawai: http://vimeo.com/41372857
Very
recently I ordered a couple of Lee Valley chipbreakers. One was for a
Stanley #3 I had restored, and the other was for a #4 1/2. There were
also PM-V11 blades to go with them.
Today I had the thought to
take some photos and thereby share with others my observations about
this purchase. For contrast I shall use #3 chipbreaker/blade
combinations from Lee Valley, Lie-Nielsen, and Stanley.
LV,
LN, Stanley
At
first glance the LV and LN chipbreakers are similar in shape and
design. The LV is shorter than the LN.
The LV sits firmly on
the blade, is a perfect match ...
...
as is the LN combination ...
Both
have just enough flex to pull down firmly onto the blade.
The
Stanley ...
...
needed a little extra bend in the body to create a tight bond. The
thin steel is very flexible, too much so. What happens is that when
it is set close to the edge of the blade, and then tightened, the
chipbreaker will "stretch" over the position desired (if
not careful, over the edge of the blade).
The similar designs
of the LV and LN are also evident on the reverse side ..
There
is a little more support at the front of the LV. This is not
significant once in use as the front of the chipbreaker rests on the
leading edge and not the flat. However the wide support of the LV did
make it easier to balance on the medium when lapped flat (which does
need to be done ever now-and-then).
Now the important side I
want to show is the other side - the chipbreaker screw ...
What
you will notice is that the LV screw is knurled and the LN is flat.
The LV screw is also significantly thicker (The Stanley screw is also
knurled, but it is the same thickness as the LN).
Why
is this so relevant?
Because the LV screw can be more easily
tightened with fingertips. With the LN and Stanley this is not done
as easily. Finger tightening enables the chipbreaker to be set much
more easily at the edge of the blade - set it, finger tighten it, and
use a screwdriver to finish when happy.
I
start with the blade and chipbreaker held against one another on the
bench top. The bevel of the blade is rarely exactly square to the
side, and some twisting/positioning is needed that required to centre
it over the edge. The side reference from the bench is no longer
there at this point. It is helpful having the chipbreaker tight
enough to move by hand but not move on its own accord. A decent grip
on the screw helps in this regard.
This
is of particular relevance when setting the chipbreaker ultra close
to the edge of the blade.
Here
is the LV being adjusted ..
The
other item that may simply pass by unnoticed is the hole for the frog
screw. The LV is long, and this enables one to use a screwdriver
blade as a hammer to adjust it rearwards.
The
LN has a small round hole - very neat, but it makes it difficult to
adjust in the same way.
The
shorter LV and Stanley chipbreakers expose more or the blade slot,
and the screwdriver blade again can be used as a hammer to tap the
chipbreaker forward. The longer LN chipbreaker leaves open none of
the blade slot open, and cannot be used to adjust in the same way
(refer to the initial photo for illustration).
It is relevant
to note that the front edge of the LV and LN chipbreakers both angle
at 25 degrees. This is too low for Bailey-type planes with a 45
degree bed. A secondary microbevel of about 45-50 degrees needs to be
honed. This is easily and quickly done freehand. More on this in
further article.
The
angle at the leading edge of the Stanley chipbreaker is generally
good to go, while both the LV and LN need to have this honed in. The
amount this angle needs to be is debatable. I know Kees completed his
experiments and concluded that he likes 45 degrees. The Kato video
suggested 50-80 degrees, however their bed was, as I recall, 40
degrees. Kees probably was 45 degrees. I have experimented with frogs
from 45 to 55 degrees, and consider that each chipbreaker is ideally
suited to a different angle at the leading edge. In practice it does
not make too much difference.
The
"problem" that I experienced with the Stanley chipbreakers
I have is that in tightening them down, they "stretch" a
little, and this alters their setting at the leading edge. It is
frustrating when it pops the chipbreaker over the edge of the blade!
The LV and LN chipbreakers are less flexible. As I said, I like some
spring - which the LV and LN lack - but they are more reliable to set
at the edge.
A
few more chipbreakers
to
add to the mix.
I
had originally posted this information on a couple of forums. I ask
asked to add a few more chipbreakers for comparison.
First
the Clifton.
This comes out of my Stanley #51 (shooting plane) where it is paired
with a Smoothcut laminated blade. The Clifton uses the Record Stay
Set design, which has a removable toe (to facilitate easier
sharpening). Frankly this design is a royal pain in the youknowwhat
since the toe is not securely attached and tends to fall off. It is
held securely by the lever cap. However this arrangement does make it
more difficult to adjust close to the blade edge. After the umpteenth
time that the toe fell off, I epoxied the two parts together!
The
chipbreaker is a similar thickness to the LN and
LV.
This Hock chipbreaker
comes from a smoother I received from Jim Krenov, where it is paired
with a Hock blade. Of interest, when the plane arrived the
chipbreaker was set 1/16” from the edge of the blade. The mouth is
tight. The plane had been used. From this I would conclude that Jim
did not set up his planes with the chipbreaker.
Here
are Clifton and Hock chipbreaker screws flanking the Lee Valley
…
The
Clifton screw is identical to the Stanley – having stated this, it
may very well be a Stanley as it has been so long. However, in the
deep recesses of what is left of my brain is the memory that the
Clifton screws used a different thread to Stanley.
The
Hock screw is slightly thinner but does not feel so. It is second to
the LV to grip. The reason for this is that it, as with the LV, have
coarse knurling. The knurling on the Stanley and Clifton is very
fine, giving some but not as much grip as the LV and Hock. The LN has
no knurling, and the smooth circumference makes it the hardest to
grip.
Here
is a summary of screws dimensions:
The
differences in screw size do not look great on paper. However add in
coarse knurling and the little extra height of the LV is very
noticeable and makes it stand out. The coarse knurling on the Hock
brings it in second. The Clifton and Stanley come in equal third,
with the LN bringing up the rear.
And
here is the answer to the question that will be asked: the LV screw
fits the LN chipbreaker.
With
regard the leading edge angles of these chipbreakers, that is an
article for another time.
Regards
from Perth
Derek
December 2013