|Microbevels front and back.|
|Use a jig.|
|Copyright (c) 2002-15, Brent Beach|
The LN #62 is a low-angle, bevel-up plane. The iron is bedded at 12 degrees. The iron comes with a 25 degree primary bevel. I sharpened it using my standard sharpening procedure. The front (bevel side) microbevel angles were (very nearly) 29, 29.7, 30.4 degrees. The back (non bevel side) microbevel angles were (very nearly) 2.4, 3.5, and 4.3 degrees.
Adding the bedding angle to the last front microbevel angle gives a final attack angle of 42.4 degrees, just a little less than a standard bench plane.
The clearance angle, the bedding angle minus the last back bevel angle is 12 - 4.3 = 7.7 degrees.
|Con||The blade is the least durable blade I have tested. Blade wear, measured by the width of the downward facing wear bevel, was twice as high as any other blade covered by these tests.|
There has been considerable chatter in hand tool circles for the last couple of years about the performance of bevel up planes. This test, aside from looking at the durability of the LN O1 steel blade, is an attempt to understand why these planes work so well.
The idea has been to increase the front bevel angle (in part by increasing the primary angle, in part by increasing the microbevel angles) by between 10 and 15 degrees, increasing the effective attack angle from around 42 degrees up to 57 degrees or higher.
Before - upward facing side
The bevel side (faces up during use) at 200 times magnification. The three microbevels
Before - the downward facing side|
The back side (faces down during use) at 200 times magnification. The three microbevels
After - the upward facing side
The bevel side, 200 X magnification, after 150 passes along the 4 foot Douglas-fir board.
Recall that this is the upward facing surface.
I have numbered 8 regions in this picture. This picture has been digitally enlarged to better show the regions.
The upper wear bevel, combining regions 2 through 5, is a total of .004" wide, or about twice the thickness of the shavings. The high wear section of the upper wear bevel is wider than I have seen on other irons.
After - the downward facing side|
The back side, 200 X magnification, after 150 passes along the 4 foot Douglas-fir board.
Recall that this is the downward facing surface. The mark was added after sharpening and before use to help locate the same part of the blade for all subsequent images.
The numbered regions are
The interesting part of this test was that the plane was still performing pretty well, even with this very wide downward facing wear bevel.
Blade stiffness is proportional to the cube of the blade thickness. When compared to Sweetheart era Stanley irons which were typically around 0.08" thick, the LN blade is over 7 times as stiff. This much greater stiffness means the blade/plane geometry changes much less during use. Remember that flex at the blade tip of only 0.001" makes it impossible to take consistent shavings of even as much as 0.002" - a reasonable goal during final finishing.
The LN #62 plane uses a screw cap rather than a lever cap. It is very easy to tighten the screw cap without affecting blade set. The cap is very strong and can provide a great deal of pressure on the iron directly above the bed.
The strength of the screw cap, the ease of use, the pressure it is able to exert, all combine to produce an effect that cannot be obtained with a Bailey style lever cap.
There blade/bed interface has a very high coefficient of static friction. [I believe this is a result of the finish on the blade and on the bed.]
Unless you are careful to use only light screw cap pressure, it is impossible to adjust the depth even with the very good depth adjuster. [Unlike most Stanley planes in which it is standard procedure to set the depth with the lever cap in its "ready to use" setting.]
Once the depth is set, increasing the screw cap pressure is simple and does not affect the set.
This ability to resist motion along the bed is crucial in a low angle plane. The LN #62 handles this very well.
When people sharpen a plane blade, they sharpen the bevel. Bevel down planes have the downward wear bevel, the crucial wear bevel as far as plane performance goes, on the bevel side of the iron. Working the bevel then removes the downward wear bevel.
Bevel up planes have the downward wear bevel on the back of the iron. People who do not spend enough time working the back of the iron will leave the downward wear bevel in place, even if they have renewed the bevel side of the iron.
Bevel up planes require a blade sharpening procedure that removes the wear bevel on the back side of the iron.