More about steel grades and edges

[Modernist]

This subject generates endless debate, as it should, as it is the essence of edge tool performance.

The crumbling difficulties of A2 generally, but not always, appear at honing angles less than 32 deg and so can be avoided. Any problems at greater angles tend to suggest a tempering problem. This makes A2 the ideal material for high angle irons where the enhanced wear resistance is an advantage.

Carbon tool steels such as O1 can handle 30 deg or less depending on the application but are not the universal panacea. Grinding angles may have an influence in some cases, such as Japanese laminated blades, where the edge steel is particularly brittle but generally I am not sure have any effect on the outcome.

As an illustration the pic below shows an O1 blade ground to 25 deg and honed to 27 from a Veritas Skew block plane. This was used for end grain work on hard american cherry and you can see clearly the damage to the edge.I increased the honing angle to 30 deg and solved the problem. I also suggest the grinding angle has no effect at all on the outcome as the problem is clearly limited to the sharpest 10% or so of the edge.

 

[No skills]

Is the A2 a type of stainless steel? (sorry if thats a dim question).

Out of personal interest... how do you remove the burr when sharpening? back and forth or with a sideways movement?

 

[Harbo]

Doesn't matter as long as you keep the blade flat.
Slicing carefully through some softwood will remove it too or carefully using your palms.

Google A2 steel - lots of info about its composition etc.
It isn't Stainless.

Rod

 

[Phil Pascoe]

Understandable confusion- you can get A2 stainless.

 

[No skills]

Thats prolly where I got that thought, had some A2 stainless fixings for something last year.

 

[Alf]

As an illustration the pic below shows an O1 blade ground to 25 deg and honed to 27 from a Veritas Skew block plane. This was used for end grain work on hard american cherry and you can see clearly the damage to the edge.I increased the honing angle to 30 deg and solved the problem.

An alternative that's often overlooked - which is why I throw it into discussion of this sort at any opportunity (sorry) - is using a small back bevel. That way you can increase the bevel angle while retaining the lower effective pitch in BU planes. Often not necessary, but potentially a useful dodge to remember.

 

[Modernist]

As an illustration the pic below shows an O1 blade ground to 25 deg and honed to 27 from a Veritas Skew block plane. This was used for end grain work on hard american cherry and you can see clearly the damage to the edge.I increased the honing angle to 30 deg and solved the problem.

An alternative that's often overlooked - which is why I throw it into discussion of this sort at any opportunity (sorry) - is using a small back bevel. That way you can increase the bevel angle while retaining the lower effective pitch in BU planes. Often not necessary, but potentially a useful dodge to remember.

I hadn't considered using a back bevel on a BU plane but no reason why not and it would do what you suggest. I was experimenting with the very low angle in the hope that the skew would allow it to work, but regretfully not. It is just possible that there was an element of new mushy edge syndrome but I doubt it. The cherry was as hard as the hammers of hell (and purple) so it was a real test.

No one has taken up the point about the effect or otherwise of the grinding angle. Personally I cannot see it have any influence here or indeed elsewhere other than Japan.

 

[Aled Dafis]

I agree about the grinding angle issue, I can't see it making any difference, hence all my edge tools are ground at around 23degrees.

Rob Cosman goes much lower with his Lie-Nielsen A2 chisels, I'd hazard a guess at somewhere between 15-18degrees based on the length of his bevels, check out some of his videos on his youtube channel.

Have a look at this video (there's a good look at his bevels at around 2.10 when he pares some end grain pine)
http://www.youtube.com/watch?v=cOvkNuwO_YM

Cheers
Aled

 

[TheTiddles]

"Stainless" steel is a general term, technically it's rubbish but in general, steel with a high degree of chromium (10-11% or above depending on what standard system you apply) is "stainless", of course it's not totally stainless, it's just more resistant that steel with less chromium in. A2 tool-steel is about 5% Cr so isn't technically "stainless".

One thing to mention with steel that most people don't know is that there are literally thousands of forms one particular composition can take, depending how you treat it, so a great performance steel can be ruined by heating/cooling/working it, similarly, the reverse is possible.

Aidan

 

[Cheshirechappie]

The descriptions 'A2' and 'A4' applied to stainless steel fasteners do not accord with any British Standard, American standard or Euro standard that I know of. I suspect they are one company's commercial name. They have absolutely no relation to the tool steel grades using those designations.

According to the Screwfix website, 'A2' is grade 303 stainless, and 'A4' is grade 316 - '303' and '316' are designations that steelmakers and steel stockholders would recognise. The former is a moderately corrosion-resistant free-machining grade, the latter is more corrosion resistant (and a s*d to machine). If you want fasteners for a marine environment, or somewhere close to the seaside, use the 316, otherwise 303 will do for most normal conditions.

 

[dunbarhamlin]

Rob Cosman goes much lower with his Lie-Nielsen A2 chisels, I'd hazard a guess at somewhere between 15-18degrees based on the length of his bevels, check out some of his videos on his youtube channel.

Have a look at this video (there's a good look at his bevels at around 2.10 when he pares some end grain pine)
http://www.youtube.com/watch?v=cOvkNuwO_YM

Cheers
Aled

IIRC Rob's LN chisels are O1 one offs (not from the current crop, but made especially donkey's year back.)

 

[Tony Spear]

The descriptions 'A2' and 'A4' applied to stainless steel fasteners do not accord with any British Standard, American standard or Euro standard that I know of. I suspect they are one company's commercial name. They have absolutely no relation to the tool steel grades using those designations.

According to the Screwfix website, 'A2' is grade 303 stainless, and 'A4' is grade 316 - '303' and '316' are designations that steelmakers and steel stockholders would recognise. The former is a moderately corrosion-resistant free-machining grade, the latter is more corrosion resistant (and a s*d to machine). If you want fasteners for a marine environment, or somewhere close to the seaside, use the 316, otherwise 303 will do for most normal conditions.

Makers of kitchen pots and pans use 304, but are fairly careful about how they use the word,
(they call it "rostfrie). 316 is the most prevalent generally used "Stainless Steel" that lives up to it's description, but it is prone to crevice corrosion, so that's where 316L (used mainly for seawater) and it's various relatives come in to play.

Beyond that, we come into the realm of Duplex (Austenic/Martensitic) steels.

 

[Jake]

The descriptions 'A2' and 'A4' applied to stainless steel fasteners do not accord with any British Standard, American standard or Euro standard that I know of. I suspect they are one company's commercial name. They have absolutely no relation to the tool steel grades using those designations.

According to the Screwfix website, 'A2' is grade 303 stainless, and 'A4' is grade 316 - '303' and '316' are designations that steelmakers and steel stockholders would recognise. The former is a moderately corrosion-resistant free-machining grade, the latter is more corrosion resistant (and a s*d to machine). If you want fasteners for a marine environment, or somewhere close to the seaside, use the 316, otherwise 303 will do for most normal conditions.

http://www.bssa.org.uk/topics.php?article=1

 

[Cheshirechappie]

The descriptions 'A2' and 'A4' applied to stainless steel fasteners do not accord with any British Standard, American standard or Euro standard that I know of. I suspect they are one company's commercial name. They have absolutely no relation to the tool steel grades using those designations.

According to the Screwfix website, 'A2' is grade 303 stainless, and 'A4' is grade 316 - '303' and '316' are designations that steelmakers and steel stockholders would recognise. The former is a moderately corrosion-resistant free-machining grade, the latter is more corrosion resistant (and a s*d to machine). If you want fasteners for a marine environment, or somewhere close to the seaside, use the 316, otherwise 303 will do for most normal conditions.

http://www.bssa.org.uk/topics.php?article=1

No, Jake - I wrote that.

Another bl**dy BS EN ISO spec to confuse everybody, eh? Oh for the happy days and simplicity of straightforward British Standard specs....

So the information given on the Screwfix website does not accord with BS EN ISO 3506, which gives the A2 grade as equivalent of grade 304, not 303. Typo by Screwfix, perhaps?

The chemical analysis specs are pretty broad as well. Gives the steelmakers a bit of latitude, I suppose - anything not meeting the tighter specs for engineering grades can go for boltmaking.

 

[Jake]

No, Jake - I wrote that.

Sorry about that both of you and fair cop - I quoted the second post as I was going to add something to Tony, changed my mind and then deleted the wrong square brackets.

Another bl**dy BS EN ISO spec to confuse everybody, eh? Oh for the happy days and simplicity of straightforward British Standard specs....

Some might think that the fact (IIRC) they get to charge everyone for a copy might have a little to do with it.

So the information given on the Screwfix website does not accord with BS EN ISO 3506, which gives the A2 grade as equivalent of grade 304, not 303. Typo by Screwfix, perhaps?

The chemical analysis specs are pretty broad as well. Gives the steelmakers a bit of latitude, I suppose - anything not meeting the tighter specs for engineering grades can go for boltmaking.

They say as much about the latitude. I guess you have to go up a grade to bolt together your stock with the same quality! I didn't look to see if 303 meets A2, I assume it doesn't from what you say. So either a bit of latitude being taken by Screwfix or a typo.

 

[David C]

Brian,
Great photos and I totally agree with your grinding policy.

Rob Cosmans 17 degree chisels for soft pine endgrain are A2.

He has some interesting observations on his forum. http://robcosman.memberlodge.com/forum hand tool discussion, page 11, low chisel angles.

 

[Jacob]

http://www.youtube.com/watch?v=cOvkNuwO_YM
What Cosman doesn't explain is why he want to flatten his chisel faces. In his demo he slides the chisel in but to make it cut he has to lift it a gnats. You can see him do it and he says it as he does it.
Obvious really.
But once it's lifted the face is no longer in contact with the wood except of course for a tiny bit just behind the edge. So except for that bit, it makes no difference to anything if the face isn't flat and shiny.
Best if it's flat to convex of course, or it would be impossible to pare ; a concave face would plunge into the wood, the edge wouldn't be steerable up or down.
Which is exactly what Cosman discovers - and why he fails to pare along the wood in his demo - his chisel plunges!
All in all a very neat demo of why flat faces are bad news. It needs to be fractionally convex ("bellied" as they say) to give you control. Carvers know this of course, and their chisels may have bevels on both sides.

If you want to pare along a surface; flat face is bad, concave face is worse, slightly convex face is best.

Thanks Rob for a demonstration of what not to do! I'll definitely bear it in mind. :lol:

PS I'd add - the bit of extra pressure you put towards the edge when you have the chisel face down to remove the burr, is probably enough to give you that tiny convexity which makes paring possible.

 

[David C]

The OPs post was about grinding and honing angles, nothing to do with chisel faces.

There are three reasons for flattening and polishing a chisel face.
Manufacturers grinding marks must be removed to get the sharpest edge, the finer the finish the sharper the edge.
A flat back jigs and guides a straight cut.
A flat back ensures that the wire edge will be removed on the polishing stone.

You appear to have misunderstood the demo. The chisel was lifted minutely to start the cut but the cut itself was flat.

It really is amazing how cock eyed and unhelpful your views are, I do hope no one takes them seriously.

David Charlesworth

 

[Jacob]

...
You appear to have misunderstood the demo. The chisel was lifted minutely to start the cut but the cut itself was flat.

No it wasn't. It goes into a dip.Have another look, you will see what I mean. I think I've understood the demo fairly well. RC didn't seem to have much idea himself, waffling away as he was!

It really is amazing how cock eyed and unhelpful your views are, I do hope no one takes them seriously.

In the end people make up their own minds.

Where did this flat face nonsense originate? It's obviously wrong, or pointless at least.

 

[Jacob]

...
There are three reasons for flattening and polishing a chisel face.
Manufacturers grinding marks must be removed to get the sharpest edge, the finer the finish the sharper the edge.

Yebbut only needs doing near the edge - you don't have to polish the whole tool!

A flat back jigs and guides a straight cut.

Not in RCs demo - he loses control and goes from paring to digging a notch, in one move! :lol: He doesn't even seem to notice - what a performer!
I don't think "guiding" is much of an issue. A bit of candlewax would help. Mirror finish is getting silly!
Anyway we have planes for straight cuts.

A flat back ensures that the wire edge will be removed on the polishing stone.

Perfectly possible to remove the wire edge from any shaped edge including rounded bevels, even if both sides rounded

....
It really is amazing how cock eyed and unhelpful your views are, I do hope no one takes them seriously.....

I'd say the same to you. A lot of people are wasting their time and energy in these pointless polishing rituals.