I find it hard to get a good edge at a high honing angle like 47°. I suspect your blade is getting dull. Then that large, dull wedge is hard to set well, as I discussed in the post, it attacks the wood with a lot of pressure before the fibers are severed, and then springback of the compressed fibers rides the cutting edge, with only 12° of clearance to begin with, away from the surface. That’s my best guess as to what’s going on.

I don’t think wear on the flat side of the blade, per se, is the cause of this problem, but that certainly occurs on all bevel up blades bedded as low as 12°, regardless of the honing angle. Personally, I think BU planes should have a bed closer to 20°, but that is another matter that I discussed in an earlier post (June 2010).

Try sharpening your BU jack plane blade with a secondary bevel of about 38° and I bet it will work better.

You can use your bevel-down jack plane with a 45° frog and the blade sharpened at 30-32° and take diagonal strokes. If you really need a higher angle, you could get a high angle frog, or, much easier, get an extra blade and add a 10-15° back bevel to yield an attack angle of 55-60°.

As usual, there’s more than one good way. Good luck. Let me know how it goes if you get a chance.

Rob

When I sought an explanation, the one answer I got had to do with wear bevels and loss of clearance angle. If it’s right, then it’s a major limitation of a bevel up plane bedded at 12 deg, and it’s been making me wonder if I need a bevel down plane with a high angle frog. But could there be some other explanation? I’m wondering if this is connected to your remark about difficulty in setting the blade projection. Is it difficult to set the blade projection with any high angle configuration? Or is this a special feature of the bevel up plane?

(Note that I ended up with that high angle because I kept getting tear out as I jointed canarywood that had swirling grain around pin knots.)