Quote Originally Posted by Chris Griggs View Post
The 35 degree bevel gives a good bit more longevity to carbon steel. It also makes it so the edge fails better. It dulls more consistently rather than chipping or rolling so as it wears you are less likely to end up with streaks from micro chipping and rehoning is more consistent and quicker. I just started doing this with my smoother (and only my smoother) on Dave Weavers advice...in theory it creates a clearance issue, in practice I have found it to be a noticeable improvement.
It improves the resistance to chipout on everything, carbon, A2, M2. Steve Elliot did a project about 10 years ago or something where he examined the final angle that A2 was optimized, and his sample, it was 32 degrees, I think. That's about where edge longevity and clearance will be maximized as a combination (i.e., maximum clearance while still not chipping out).

If you finish with a smoother (and no sanding and no scraping), chipout avoidance is important. I don't do it on any of my other planes, though, either, I just don't care to take the time to put an iron in a guide.

The couple of times I've tested irons against each other, when they were similar types, the one that chipped out first always lasted the least. It takes forever to do a realistic test on an iron in wood if you sharpen it properly, though, so I did that only a couple of times. It doesn't make sense to do that kind of stuff unless you're looking for a specific answer.

If you have to do something big where you have to finish both sides of panels, though, you get plenty of time working the good faces of a panel to tell which irons last longer.

Anyway, though, an properly cambered iron that fails only by wear and not chipping is an awfully nice thing to have in a smoothing plane. Zip two passes across a panel to finish plane it and done.