First attempt at freehand sharpening!

[Jacob]

...as this must inevitably result in a curved edge that cannot cut well...

To my eye, this looks like the author had rounding over in mind, since the only (sharp) edge which cannot cut well would be one which was too obtuse for the application.

Yes , since a rounded under sharp edge will cut perfectly well.
BB & co seem to think that I am the first person in the universe to discover this, which is flattering but very unlikely to be true!

 

[Paul Chapman]

a rounded under sharp edge will cut perfectly well.

Using your method, Jacob, you might manage to get the edge sharp but a rounded bevel (particularly in the case of chisels) is not a very efficient shape. If you draw out on a piece of paper a blade with a straight bevel and one with a rounded bevel, it becomes self-evident that the rounded bevel idea is flawed in that there is a greater mass of metal behind the edge which has to be forced through the wood.

When we were discussing this over on the other side many moons ago, I compared a pig sticker chisel which I had bought second-hand and which had a rounded bevel with one which I had honed with a straight bevel. The one with the straight bevel cut far more effectively.

But, as you say, use whatever method you wish.

Cheers :wink:

Paul

 

[Jacob]

... If you draw out on a piece of paper a blade with a straight bevel and one with a rounded bevel, it becomes self-evident that the rounded bevel idea is flawed in that there is a greater mass of metal behind the edge which has to be forced through the wood.

Not self evident at all. Quite the opposite. If you round under a flat bevel (i.e. take metal off the heel to round it , but without touching the edge) there will be less metal behind the edge, not more.

... I compared a pig sticker chisel which I had bought second-hand and which had a rounded bevel with one which I had honed with a straight bevel. The one with the straight bevel cut far more effectively....

Probably was sharper. Did you hone them both to give them exactly the same edge angle with the same degree of sharpness? If not then try it. I doubt you will notice any difference except that the straight bevel will be less use for cleaning out corners in stopped mortices and will perhaps be less easy to loosen by levering.

 

[dunbarhamlin]

The other consideration is that it is perhaps easier to grasp the notion of maintaining an angle throughout the stroke (though it took me some time to grok what that really entails - which absolutely isn't locked elbows and wrists) than the arced motion returning to the same angle at the start of the stroke. This would particularly be the case in the absence of a demonstration. When I was taught, no great emphasis was placed on the flatness of the bezel, though flatish was the product of the method shown.

 

[Paul Chapman]

try it. I doubt you will notice any difference

Blimey, Jacob, read what I said. I did try it and there was a difference - the chisel with the straight bevel cut more effectively.

Cheers :wink:

Paul

 

[Jacob]

try it. I doubt you will notice any difference

Blimey, Jacob, read what I said. I did try it and there was a difference - the chisel with the straight bevel cut more effectively.

Cheers :wink:

Paul

OK but whatever it was it wouldn't have been the shape of the bevel. You will just have to take my word for it.
nb I've cut 100s of mortices by hand - mostly in the early days before I had any machines not even a router.

 

[bugbear]

...as this must inevitably result in a curved edge that cannot cut well...

To my eye, this looks like the author had rounding over in mind, since the only (sharp) edge which cannot cut well would be one which was too obtuse for the application.

Indeed - I'm far from sure I agree with what is said here.

That wasn't the point I was trying to address - I find sticking to one point at a time more conducive to conclusions when discussing something.

Assuming the books reflect the working practice of the authors and/or what they were teaching in the technical colleges, the deliberately rounded bevel was NOT conventional practice.

BugBear

 

[Jacob]

....
Assuming the books reflect the working practice of the authors

You can't assume that.

and/or what they were teaching in the technical colleges,

May well have been just their interpretation of a "proper"method "do as I say not as I do"

..the deliberately rounded bevel ...

Nobody is suggesting that you should deliberately round a bevel. I could explain (yet again :roll: ) what I am on about but if you don't pay attention then it's a waste of time.

was NOT conventional practice.

BugBear

As the slightly rounded bevel (arrived at incidentally, not deliberately, by dipping)* avoids rounding over AND makes sharpening easier,** it is absolutely certain that it was (and is) commonplace.
*see earlier extensive explanations BB and try to concentrate!
** non of that locking the elbow/wrist/hip/knee/nose, steady rocking on balls of feet nonsense.

 

[bugbear]

....
Assuming the books reflect the working practice of the authors

You can't assume that.

and/or what they were teaching in the technical colleges,

May well have been just their interpretation of a "proper"method "do as I say not as I do"

Your argument now degenerates into assuming respected authors were just making stuff up?!

Ah - I have it - perhaps "Jacob" is also describing some idea that isn't his actual practice.

BugBear

 

[andy king]

As the slightly rounded bevel (arrived at incidentally, not deliberately, by dipping)* avoids rounding over AND makes sharpening easier,** it is absolutely certain that it was (and is) commonplace.
*see earlier extensive explanations BB and try to concentrate!
** non of that locking the elbow/wrist/hip/knee/nose, steady rocking on balls of feet nonsense.

Where is the 'commonplace' evidence of this Jacob? All the text books for generations have given 'Trad' methods (to quote yourself) and you constantly refer to 'trad' as the only way, but now you don't want us to follow that route?
The evidence i've seen is for the reasons I gave, not because it's quicker or easier, its a workaround for a situation.
You always call for evidence when you disagree with anything yet never furnish any of your own to back up, to use your own words 'nonsense'.
Instead of making snippy putdown comments all the time, (such as 'try to concentrate' which offer nothing to this thread other than to antagonise) a rational reasoning and evidence would put the argument/discussion to bed once and for all.
Incidentally, when you were doing your woodworking course, what was the desired edge profile taught as being 'correct practice' to you at that time?

 

[Jacob]

Well prove that nobody else in the world does it my way. (Not really my way - just a way)
I think I'll rest my case or this could run and run!

Best of luck stubtoe, don't let them put you off!

 

[andy king]

Well prove that nobody else in the world does it my way. (Not really my way - just a way)
I think I'll rest my case or this could run and run!

It's not about proving this Jacob, it's your quote that 'it is absolutely certain that it was (and is) commonplace.'
As I said, you should furnish your evidence of this as you always call others to do so.
I doubt you are unique in how you hone, but i would hazard a pretty good guess that you are in a very small minority compared to 'trad' methodology and percived correct working methods that are still taught to this very day.
I doubt your 'round under' evidence is likely to emerge in its droves, although you'll see plenty of 'round over' stuff out there IMHO.

 

[Sgian Dubh]

... Yes , since a rounded under sharp edge will cut perfectly well.

Jacob, I must admit I'm still struggling to get a visual grip on the difference between a 'rounded' bevel (presumably a convex profile) and a 'rounded under bevel', or whatever you are calling it. Isn't one of these 'rounded under bevels' a convex profile too?

Perhaps drawings or photographs of the difference between these profiles might help.

On the other hand I'm a dedicated freehand sharpener, and I don't incorporate rounded (convex) grinding angles on the bevel-- the grinding angle is concave of course, and I generally only sharpen the tip of the tool until it needs a bit of regrinding (for whatever reason). It doesn't matter to me if another worker uses a jig so long as the job is done quickly in a working environment (different to hobby use where time is perhaps less important). Slainte.

 

[dunbarhamlin]

At the cutting edge, the tangent of the arc of the rounded under bezel is maintained at the same angle as would be maintained using a flat bezel.

Not the effect of the bevel creep (rounding over) caused by repeatedly raising the angle on the stone to get "just a little more" life out of an edge, which progressively increases the bevel (angle.)

 

[Jacob]

As Steve says.
Quick sketch here:

1 Flat bevel and edge at 30º
2 Rounded over bevel hence edge angle higher
3 Rounded under bevel edge stays at 30º.
The shape of this bevel is irrelevant except that it makes sharpening easier as compared to aiming for a perfect flat one.

The last time I posted this Jason got his crayons out and coloured it in.

 

[Racers]

Hi, Jacob

The rounded bevel has a longer face, won't this lead to longer sharpening time as you have to remove more metal?


Pete

 

[Jacob]

Hi, Jacob

The rounded bevel has a longer face, won't this lead to longer sharpening time as you have to remove more metal?


Pete

Strewth I've been here before so many times!
The answer is no. AOTBE you would remove a longer but thinner layer than with a flat bevel i.e. the same amount of metal.
It's quite difficult to explain this but nevertheless it is true.
Area of parallelogram is base x height or volume of this prism of metal removed would be base x height x width i.e. same whatever the edge angle.

 

[bugbear]

As Steve says.
Quick sketch here:

1 Flat bevel and edge at 30º
2 Rounded over bevel hence edge angle higher
3 Rounded under bevel edge stays at 30º.
The shape of this bevel is irrelevant except that it makes sharpening easier as compared to aiming for a perfect flat one.

The last time I posted this Jason got his crayons out and coloured it in.

So if the wobble/dip/whatever is (say) 5 degrees a rounded over bevel starting at 25 degrees is identical with a rounded under bevel ending at 30 degrees.

They're both convex, 25 degrees at the arris, 30 degrees at the edge.

BugBear

 

[Racers]

Hi, Jacob

But with a seconary bevel you will be removing a lot less metal, untill you need to redo the primary bevel.

Pete

 

[andy king]

Hi, Jacob

But with a seconary bevel you will be removing a lot less metal, untill you need to redo the primary bevel.

Pete

Yep, I agree.
Jacob's method is based on the theory that everyone will be maintaining a single flat bevel profile, not introducing a secondary honing bevel as is the norm, and traditionally taught.
Traditional secondary bevel honing will remove less metal as there is less in contact, even as the wearing surface increases, and in theory, if a secondary 30 degree bevel is maintained, rather than reground as is normal, it will eventually replace the primary 25 degree one, but we've been down this route many times before...
End of the day, if it works whatever the method, all is well, but it is each to their own.

cheers,
Andy