Sharpening A2 steel blades vs High carbon question

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I own a LN 4 ½ plane and a stanley #4 retrofitted with a Hock A2 blade.

After sharpening them as I sharpen all my planes, that is without secondary bevel and no rule trick I find that they get nicked very easyly, especially with hard woods and end grain planning.

On the other hand I have a Stanley # 5 retrofitted with a Hock High carbon blade that planning the same woods and end grain doesn’t get nicked as easyly.

In order to give it a try I sharpened both A2 blades as it is recommended in LN web page and oh! surprise! they don’t get nicks as before.

It is my assumption (because I have no idea to what is due) that the A2 steel is more brittle than carbon steel and maybe that the crystals of A2 steel are bigger than carbon steel hence its fragility when very thin or sharp edges are made.

I wonder if any of you have noticed the same, and wheter I might be right in my assumption.
 
Tony, I have not been as observant as you have, but your suggestion that A2 edges may be more durable at an angle higher than 25 degrees is consistent with the hearsay I have heard. As for the reason, I don't have a clue, way above me technically. Why don't you drop LN an email and ask them about the truth of this and the reason?

If you can wait that long, I am going to a LN Hand Tool Event in Port Townsend, WA on the 12th of September, and I will ask there and report back what they say.
 
I sent them an e-mail today and this was their answer, a couple of hours later.

"As you have noticed, the edge does not hold up quite as well at the 25 degree angle. We recommend a secondary bevel simply to make sharpening easier. You are removing less material so it takes less time. We have determined that A2 steel holds its edge best at between 30-35 degrees (or steeper). If you do not want to regrind your blade, but also do not want to work with a secondary bevel, you can sharpen the blade at 30-35 degrees and just let that new bevel grow until it becomes the primary bevel. If you are not using a honing guide, so you cannot guarantee an angle, then you can send the blade into us and we will regrind it to the new angle and send it back. Another option is that we are now making O1 blades for the #4-1/2, these do not give the edge life of an A2 blade at 30 degrees, but you can sharpen them at the 25 degree primary grind with no ill effect. Please let me know if you need anything else, or would like to set up a return.

At least they are honest and quick with their answers to customers .:thumb:
 
Hi Tony

While 30 degrees is a better angle (than 25 degrees) for A2 steel, you should also try grinding the blade back (even a 1/32" may be enough) as there may be some brittle steel at the edge. This has worked for me.

Just for note, I grind and hone my A2 blades for the LV LA Jack at 25 degrees when used on the shooting board. They have held up very well over a number of years.

Regards from Perth

Derek
 
Hi Tony

While 30 degrees is a better angle (than 25 degrees) for A2 steel, you should also try grinding the blade back (even a 1/32" may be enough) as there may be some brittle steel at the edge. This has worked for me.

Just for note, I grind and hone my A2 blades for the LV LA Jack at 25 degrees when used on the shooting board. They have held up very well over a number of years.

Regards from Perth

Derek
Thanks Derek, I may give it a try before changing the bevel angle of my plane.
 
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