BU angle

[Adam Cruea]

I have a LN 60 1/2 here that I got about 2 weeks ago (already one of my favorite planes), and the blade is beveled at 25*.

I'm just curious, but why? I know cranking the edge up to 30* will make the edge last longer, but what would be the drawbacks of doing so? I also know that making the angle greater will cause the plane to start acting like a scraper, but that's not what I want.

On the bevel down planes, it's a no brainer when it comes to the angles, and the frog alone is what determines the cutting angle. However, this is my first foray into bevel-up, so before I do something that's going to compromise the extremely thin shavings this thing can take, I'd like to get the different opinions of some of the more experienced crowd. What's your sweet spot on the little hand-held planes regarding angle?

Thanks, y'all!

[Derek Cohen]

Hi Adam

A higher bevel angle will lengthen the life of the edge, however a higher cutting angle will be slightly harder to push through end grain, and you will not get as smooth a finish. On the other hand, a higher cutting angle is less lighter to cause tearout on edges or face grain, such as when chamfering.

Regards from Perth

Derek

[David Weaver]

low 30s bevel angle is the lowest you'll get A2 around 60-62 hardness to not have small chipouts, meaning the edge will fail only from wear.

I don't know what a similar carbon steel angle is, probably 3 or so degrees less.

Depending on what you do, I would use at least 30 degrees. If cutting straight across soft grain is all you do, that would fit in the depending category (as in you might choose to go below 30 degrees).

Steve Elliot did a nice edge test a while ago with A2 and other steels, and his magic number for what you would call "modern A2", the stuff that's everywhere now all at pretty much the same hardness, was 32 degrees final bevel angle.

we're talking only about planes here. A2 is not a great chisel steel.

[Jim Koepke]

One of my main uses for LA BU block planes is cutting end grain. The lower the angle of the blade the less effort is required to shear off the end grain.

Depending on your sharpening set up it wouldn't be too difficult to put a small secondary bevel on the blade to see the difference. With the blade bedded at 12º if you put a secondary bevel of 33º it should act pretty much like a small bench plane without a chip breaker.

The low angle of attack working with the mouth closed has the effect of not allowing the wood to lift ahead of the blade to reduce tear out.

Wow, no replies when my answer was starting and now mine is the third.

I forgot to ask if it is A2 or O1. As David says, that my do better at a higher angle.

jtk

[David Weaver]

Correction, slightly higher than 32.

http://bladetest.infillplane.com/html/bevel_angles.html

At any rate, the first sharpening method i ever learned was charlesworth's method. When I learned to do freehand sharpening a year later, I set it aside and just honed everything around 25-30 degrees (everything meaning planes).

I went back to charlesworth's method for finishing smoothers a couple of years ago because I like to be able to finish after planing (without scraping or sanding) if I can, and that means no chipping in the edge. Charlesworth's final bevel is around 35 degrees, which is very similar to steve elliot's finding of 34 degrees. I wouldn't want to go that high on a BU plane, but I wouldn't want to fight A2 to get it to work well at 25 degrees.

[Derek Cohen]

low 30s bevel angle is the lowest you'll get A2 around 60-62 hardness to not have small chipouts, meaning the edge will fail only from wear.

Hi David

I know this is the accepted rule, however over 9 years (I looked that up :) ) of using a LV LA Jack on a shooting board with an A2 blade ground and honed at 25 degrees, I have yet to discover a blade that fails as a result of chipping (as opposed to rounding).

I can say the same thing for small block plane blades. I was quick to criticise LV's choice of A2 when they released the premium block planes, and indeed one chipped a tad when I first used it. However, this can occur with O1 or any steel for that matter than is freshly out of the oven. One grind of the primary bevel (again to 25 degrees - hollowed and honed on the hollow), and it has never chipped again. My apologies LV.

My bevel down A2 blades (from LN) also resist chipping. And why do I grind/hone them at this angle knowing that they will not last as long as 30 degrees? Because they get a tad sharper, and I prefer that and re-sharpening earlier. The new PM-V11 blades give you the best of both worlds.

Please note that I am not disputing Steve's research or David C's methods - they are correct. In the real world the A2 blades do not chip out on me, and honing lower is just a preference, not cast in stone.

Regards from Perth

Derek

[David Weaver]

I have significantly more chipout at 25 degrees, or edge deformations of all types, on planes with 25 degree bevels. They don't have to be A2 irons, that includes everything, carbon steel and all. At 25 degrees, I get edge damage almost immediately on the shoot board. I'm not a big fan of going from waxy end finish to lines in the finish due to deformation just from shooting one end.

I didn't notice the V11 iron that I had to be too terribly different than the veritas A2 iron. It was maybe like a better A2, but it wasn't defect free at 25 degrees, even just shooting cherry.

[Adam Cruea]

One of my main uses for LA BU block planes is cutting end grain. The lower the angle of the blade the less effort is required to shear off the end grain.

Depending on your sharpening set up it wouldn't be too difficult to put a small secondary bevel on the blade to see the difference. With the blade bedded at 12º if you put a secondary bevel of 33º it should act pretty much like a small bench plane without a chip breaker.

The low angle of attack working with the mouth closed has the effect of not allowing the wood to lift ahead of the blade to reduce tear out.

Wow, no replies when my answer was starting and now mine is the third.

I forgot to ask if it is A2 or O1. As David says, that my do better at a higher angle.

jtk

The LN 60 1/2 comes with an A2 blade.


Derek -

I wonder if it's because of the wood species and hardness down there in Aus? I've noticed the harder the wood, the less likely you are to get chips in the blades and the quicker they round over. It's like the softer the wood, the more it eats the steel, whereas hard woods tend to slice cleanly. Just a thought.

Anyways, thanks for the viewpoints, all. I may play around with a 30* secondary bevel since I know that things won't get screwed up now and it will just be a little harder to push. I figured that's what would happen, but I wanted to ask before hosing my new LN A2 blade.

[Curt Putnam]

Not an expert: Don't think it matters all that much if things are SHARP. I note, with interest, that my LN 102 with A2 blade came from LN at 25°. My LV LA block came with A2 at 25°. Paring chisels from Dave jeske are A2 and come at 25°. None have failed used against cherry, curly soft maple, African mahogany and oak. Just sayin......