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|Microbevels front and back.|
|Use a jig.|
|Copyright (c) 2002-15, Brent Beach|
While free and relatively simple (for a 3D drawing program), Sketchup models are accurate in scale and let you view the model from every angle.
By accurate in scale, I mean that if you specify that a rectangle (for example) has a specific size, then it has exactly that size (within the accuracy of single precision floating point numbers). If the modeller gets it right, the model is accurate.
The total width of the wear bevel and the three microbevels is just under 0.02", or about one-tenth of the width of the primary bevel. The wear bevel is about 0.0006" wide.
The plane iron could be in any orientation, so I chose to put it at the angle at which it would be use in a standard bench plane. So, the iron is bedded at 45 degrees. The back, the upper face, is at 45 degrees. The front primary bevel, the lower face, is at 45 - 25 = 20 degrees.
In order to see both faces, we are a bit under the blade looking up.
Rather than draw a model with the metal removed for the full width of the blade, I left a bit of the primary shape on the left of the image. The rest shows the shape after the first honing step.
The honing angle of the back is much smaller than the honing angle on the front.
The front and back microbevel are about the same width. You spend most of the time honing the front, just a little honing the back since the front wear bevel you are removing is much steeper on the front than on the back.
Notice that far less metal is removed in this step.
Even though the second microbevel removes almost half the first microbevel, measuring from the edge, it removes very little metal compared to the amount removed during honing of the first microbevel.
The 5 micron abrasive removes metal much more slowly than the 15 micron abrasive. It is important that you use a jig so that the metal you are able to remove is at the edge.
Again, the new microbevel is about half as wide, measured from the edge, as the previous microbevel.
The plane iron is ready to use.
The third microbevel is about 0.005" wide. Seems pretty narrow but all contact between the wood and the plane iron takes place in this very narrow band on either side of the blade. Even though you probably spend less than 30 seconds honing the third microbevel, you have fully prepared the entire contact area between the tool and the work! Amazing.
This amount of wear corresponds to a pretty dull blade.
This model has 8 surfaces, but the sequence of events in creating the model again matches the sequence of events in honing and using a plane iron.
The surfaces, from left to right: