Mujingfang (Hong Kong style) HSS iron

	Mujingfang (Hong Kong style) HSS
	Finest abrasives.
	Microbevels front and back.
	Use a jig.

	Copyright (c) 2002-15, Brent Beach

Test Summary

Mujingfang HSS iron in their Hong Kong style plane.

Mujingfang make a series of wooden planes, often from nice looking tropical hardwoods, which have High Speed Steel blades.

I bought this plane from Japan Woodworker. The online catalog says the blade is "A2 High Speed Steel". The A2 designation refers to a High Carbon Steel, not a High Speed Steel, so at least part of this description is wrong. When I asked a Japan Woodworker representative about the blade, he suggested it was in fact A6 steel (new steel type to me).

Unlike other Mujingfang planes, this one has a more or less normal cap iron for a wooden plane. The cap iron has no holes for a lever cap screw or depth adjust. The blade does have a slot almost suitable for a Stanley plane and can be used with a Stanley cap iron, once the slot is extended closer to the edge.

As of December 2007 Japan Woodworker still lists this plane in their online catalog. The plane and blade cost only $28.85, less than most replacement blades alone. If you want a very good blade in your #3 or #4 1/4 Stanley, this is the place to get it.

Here is a picture of the iron, modified for use in a Stanley plane. This is the cap iron that comes with the blade. If you want to use the blade in a western plane, you will have to use the western cap iron - which should not be a problem.

Not a pretty sight! The yellow strip is the solder line - where the High Speed Steel bit is attached to the milder steel body. This is enough steel for a lot of planing.

I drilled and filed the bottom of the slot so the blade would fit in a Stanley plane. In Stanley style planes, the maximum length from the bottom of the slot to the edge is determined by the placement of the lever cap screw.

The upper end of the slot also has to be filed to allow the Lateral Adjuster circular widget to fit.

These modifications do not affect the usability of the iron, with its cap iron, in the wooden plane.

In other tests, M2 High Speed Steel has proven to be very durable, while not suffering from the edge deterioration (chip out) associated with most A2 High Carbon Steel blades.

Pro:	Shows the excellent edge durability, somewhere between M2 High Speed Steel and A2 High Carbon Steel blades. This is a very inexpensive blade -- the plane and blade together cost less than most replacement blades.
Con	Has to be the ugliest blade I have ever seen. Fortunately, all the nasty bits are hidden when the blade is in the plane.

The Tests

February 5, 2005.	While designed for use in a wooden plane, this blade was modified for use in a Stanley plane. The test was done using a "between the wars" Stanley #5-1/4 - the plane I use for testing all 1-3/4" blades that will fit in it. This blade is thicker than standard Stanley plane irons at 0.097", but fits in this plane.
February 26, 2005.	Standard test sharpening, but rather than use the blade in the #5-1/4 in which I normally test 1-3/4" blades, I used the same #604-1/2 used to test the Stanley HSS blade. This is one of a series of test to see if the blade used in testing has any effect on blade performance. These are both pretty good planes -- perhaps I should have chosen a worse plane for this test.

The Results

All images are of the front bevel at 200X magnification.

The images from the second test are a little larger and a little clearer than those from the first test. During February 200 I learned that it is possible to acquire images from the QX3 other than through the software that comes with the microscope. The changes are explained in the QX3 pages.

The faq contains an explanation of the term pixel.

As delivered.

The front of the iron, 200 X magnification, as delivered.

This is a pretty good edge - well sharpened with an abrasive comparable to 15 micron 3M. Most people sharpening on oil or water stones without a jig would not produce a better edge.

There is some evidence of a finer abrasive near the edge - the dark area with fewer visible scratches suggests an abrasive with grit size like Chrome Oxide (half micron).

Right at the edge there is some evidence of a wire edge - a very narrow band that reflects light differently from the rest of the blade.

Freshly sharpened.

Feb 5, after 0.5 micron paper at 32 degrees.

The four bevels are pretty clear in this picture.

Starting with the right third, the primary bevel, dark with a few scratches.
Next, the middle third bright area is the remnant of the 15 micron first microbevel.
Next, the right two thirds of the left third, fewer bright scratches, is the 5 micron second microbevel.
Finally, the dark area at the edge with no scratches is the 0.5 micron third microbevel.

Feb 26, after 0.5 micron paper at 32 degrees.

The 4 zones are not as clear in this image, but the 0.5 micron CrO microbevel at the edge is pretty clear and quite wide -- fresh abrasive.

I added the dark line with a carbide scribe before taking the picture to help me locate the exact part of the front bevel.

After 100 passes along 4 foot douglas-fir board.

Feb 5 test. Very narrow wear bevel, about 4 pixels wide, with good edge quality.
Feb 26 test. This wear bevel is barely detectable in this picture, perhaps 2 pixels wide.

After 200 passes.

Feb 5 test.

After 200 passes (800 linear feet planed) the wear bevel is still 5 pixels, or about 0.00036", wide. The edge shows some small defects, generally less than 1 pixel in width.

This wear is more than other M2 High Speed Steel blades I have tested, less than A2 High Carbon Steel blades. The edge quality, the number of chip outs, is closer to M2 than A2.

Feb 26 test.

Again, a very narrow wear bevel, even narrower than the previous test. It appears to be around 4 pixels wide, the average wear bevel for an M2 steel blade.

Conclusion

A single test with such similar results does not tell us much about the effect of the plane on edge durability. Nor does it explain at all why there could be such an effect. Perhaps after a few more tests, if there is a consistent pattern, a search for an explanation can begin.

Test Summary

The Tests

The Results

Conclusion

LINKS

Blade Testing Page

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