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Lee Valley Chipbreaker

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:

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


December 2013