Sharpening advice

[J.A.S]

Dear All,

I'd welcome some advice on sharpening. My question is about honing a dull blade, and is doubtless evidence of dreadful ignorance .

Say you have a chisel/iron with three bevels: 23deg., 25 & 30. When the tertiary bevel is just dulled (not nicked or otherwise damaged), can that bevel alone just be re-honed on the highest grit stone? In DC's video, he shows a re-sharpening of the secondary bevel, followed by a honing of the tertiary. Is this necessary? Does a wire edge first have to be formed on the 2nd bevel before polishing the third?

Similarly, if the blade has only two bevels, of 25 degs and 30, if the secondary is just dulled (again, not chipped or damaged), can it just be honed, or does one first have to raise a wire edge on the primary bevel before polishing the secondary?

Many thanks.
Jeremy

 

[Anonymous]

Touch up the highest angle - so the secondary or tertiary bevel. Not necessarily straight to the highest grit stone though - depends on how dull it is. During work, you can touch up throughout on the high grit, but once you've got a seriously dull edge, it'd be quicker to start on a coarser grit, but still on the higher angle.

Redo the primary bevel when the size of the secondary/tertiary is such that you're 'honing' most of the thickness of the iron/blade.

That's my method, anyway.

 

[Alf]

Right, thinking aloud here, bear with me.

Three bevels
DC's method is to use the highest grit, and the highest grit only, for the third bevel, yep? (If no, please read no further and be kind when you tell me how very wrong I am) Now as I understand it, and without refreshing my memory from source material, the only reason for having the third bevel is to make that final polishing step do-able in reasonable time, yep? (If no, see advice above. :roll: ) Otherwise you might just as well have a "normal" primary grind/secondary hone set up like normal, er, like the hoi-polloi use, yep? :wink: Sooooo, if you try to raise a wire edge with that polishing stone you'll do two things will you not? 1. Take an age to get a decent fresh edge. 2. Widen the tert- tart - third bevel. I believe neither of those things are desirable, no? (Speak slowly and clearly when you refute that so I can understand why I'm so very mistaken) Now if you go back a grit and touch up the third bevel to make it quicker you'll end up also widening that bevel I believe, yep? Which will also need polishing, taking longer 'cos it's wider. (Remember, be kind when you point out where I've gone wrong) Therefore, by a process of elimination, it would seem to me that you need to do the secondary bevel and then the third, polishing step as well. Or else forget the whole thing and use two bevels like any old sharpening slob (e.g. Me)

The above deduction is based on absolutely no experience with using three bevels, no reference to DC's writings on the subject, and with a passing pang for the DVD - don't say you weren't warned. :roll:

Two bevels
Easy peasy. Bevel one is the grinding angle; only needs redoing when the secondary bevel starts getting so wide that it's taking too long to touch up the edge, or you've had a nasty-nick-out-of-the-edge-moment which needs removing. So the secondary bevel is the only one you actually hone.

Cheers, Alf

 

[Chris Knight]

At the risk of awakening the PC sharpening police...
I have tried just about every system out there and emerged semi-sane (and I have a certificate to prove it :lol from the other side.

Almost any old stone that cuts will do to establish a primary bevel and a good starting angle is somewhere between 25 and 30 degrees. A nice fine stone which may be called Arkansas, Diamond, or > 6000 grit waterstone will do to establish a secondary bevel and thereby create a super edge at anything upto five degrees steeper than the primary bevel

I am with Alf here - If a third bevel really has to be spoken of, imagine it as the one created by DC's ruler trick (that works a treat)

A wire edge is a good way of ensuring (and knowing) that you have ground as far as the real edge. It is not always noticed however, depending how you got there and therefore how big it is. Some sharpening processes just don't make a noticeable wire edge.

Coming from my carving tool sharpening experience, it pays to use the newly created edge on a block of wood (just hold the blade in your hand and hack at the wood. This breaks off any wire edge and seems to consolidate the edge somewhat. After this go back to the fine stone for a final honing. Then go to the strop ( piece of fine grained hardwood like maple - or MDF with some compound on it ) and strop the edge.

 

[Anonymous]

erm, the ruler trick is to get a back bevel, neh?

I don't actually recall reference to a third bevel in DC's books, but not seen the DVDs/vids yet...and probably don't remember the books too clearly either.

As I understand it, the main idea of any secondary or tertiary bevel is to reduce the serious honing/polishing phase, otherwise why have 2 bevels at all? Dropping back a grit or 2 for sorting a seriously dull high angle doesn't matter if you've got 2, 3, 4 or 100 bevels - it speeds the process up. Of course, if you touch up while working, you'll never get to that stage, so it's not generally an issue. If, however, you do end up with a dodgy high angle bevel, there's still no need to always go up a bevel at the same time - after all, when you have a 2 bevel edge, and the secondary's v. dull, you don't go and redo the primary every time, now do you? Nope. You just have to keep an eye on how much of the next bevel up you've reached - halfway, and it's time to move up a bevel. If that bevel's half way up its parent, time to move up again.

Which is what I was saying in my 1st reply.

 

[J.A.S]

Oh, deary me. I think I rather muddied the water by mentioning three bevels. Thus, let's remove the tertiary bevel from the equation.

Hence, let's assume we have two normal, traditional bevels. Primary is 25; secondary = 30.

Now, say, after having done some productive chiselling or planing, the blade has become dull; it's not chipped or otherwise damaged. Do we:

1. attempt just to re-hone the secondary bevel with the highest grit stone;

or,

2. work the secondary bevel on a lower grit, raise a wire edge, and then proceed to polish it on the higher grit;

or,

3. raise a wire edge on the primary bevel, and then move on to hone the secondary?

JS

 

[Frank D.]

Hi Espedair,
I don't really understand the tertiary bevel. Isn't it just another way to put off sharpening? A disadvantage I'd see is that when any bevel exceeds 1/16" or so it becomes a primary bevel (it makes the blade behave differently), so having more than two bevels on the blade changes the way the blade cuts. However, if you delay sharpening by adding bevels, it'll just take that much more sharpening when you redo your primary bevel (you'll have to take off more metal to form a new edge).
I can't really find a good concluding statement, so I guess I'll leave it at that
:wink: . Feel free to mow me down to size.
Frank D.

 

[Anonymous]

Frank - don't ask me about tertiary bevels - I've never used em, and indeed never heard of em til Jason's post - I'm just arguing, as I think you are, that a tertiary (or secondary) bevel is just there to reduce the amount of metal you have to remove when doing basic honing/touching up. Bevels only change the way the blade cuts on bevel-up irons - on bevel down, the characteristic of the cut is defined by the frog, with the bevel only really controlling sharpness versus edge longevity. I would certainly never advocate adding bevels just to put off sharpening - my reference to the 2, 3 or 100 was to make a point - it doesn't matter how many bevels you have, their primary purpose is to reduce the amount of metal you have to remove when sharpening. That applies to any number of bevels from 2 upwards, and applies equally to bevel up or bevel down.

I can see I haven't explained what I'm getting at properly, cos people keep misconstruing me! lol

JAS - my advice would be:

1) if the secondary's just a tad dull, just hone on highest grit
2) if the secondary's well dull, but the whole bevel isn't too big, drop back 1 grit, raise the wire-edge, then go to the fine grit
3) if the secondary's got to about 1/2 the width of the primary, redo the primary first.

 

[Frank D.]

Ah, now I see!
I'm quick but it takes a while...
(I wonder how many bevels it takes to sharpen a circle?)
Frank D.

 

[kygaloot]

Thanks for the sanity injection, Chris.

 

[Midnight]

Jeremy... me thinks backin up a piece might shed some clarity on this... too damn many bevels goin on ...

The primary bevel is the one the manufacturer makes; traditionally it's 25 deg, and traditionally, any work you do on this bevel is called sharpening; doesn't matter what grit you stop at, it's all sharpening...

Secondary bevels are things that we (end users) create to make the business end last a little longer. Traditionally, any work you do on this bevel is called honing 'cos yer only refining the very tip of the blade.
Clear as mud..?
I'll try it another way... your comment re wire edges on the primary... by definition, if you do that, you've totally removed the Secondary bevel.

When to hone is simple.... right after you sharpen...

Strictly speaking you can push it a bit farther than that.. but Sgean has a point when he says "if ye can see it... it's too bloody big..!!" For the benefit o delicate ears I winna go into what was said prior to that...

re-honing for too long means sharpening's gonna be a job you learn to hate.. it'll take forever cos there's so much material to remove.. don't ask me how I know this...
better policy is a quick tickle on a fine stone before changing angle to hone on an ultra fine stone... repeat whenever you need to tickle the edge and you'll get into the habit of getting it done whenever the blade says it needs honing, rather than seeing how long you can put it off for...

 

[Anonymous]

erm, the ruler trick is to get a back bevel, neh?

I.

No, not really. The ruler trick is simply to avoid polishing all of the back of the plane iron. The angle is very, very shallow and not really intended to create a bevel although it will effectively create a very slight back bevel of maybe 1 or 2 degrees.

 

[J.A.S]

Dear All,

thanks for your helpful comments.

Mike, I do know the difference between the bevels, and, thus far, have worked as you suggest. My query stemmed from the concern that I might not be doing the 'right' thing: I wondered if the proper procedure required going back to the primary bevel if the secondary were very dull. I suspected that I might be 'cheating' by only re-honing the secondary bevel.

From the posts of this thread, I think it might be safe to conclude that I haven't been cheating at all.

By the way, DC refers to a 'third bevel'; the phrase 'tertiary bevel', I'm afraid, springs from my own semantic terrorism :wink: .

Thanks again.
Jeremy

 

[Derek Cohen (Perth Oz)]

Bevels only change the way the blade cuts on bevel-up irons - on bevel down, the characteristic of the cut is defined by the frog, with the bevel only really controlling sharpness versus edge longevity.

ES, that is a nice way of summarising the interaction between blade bevel and bed/frog. I fully agree with you for the bevel up irons, but you have omitted a factor for the bevel down setup. With the latter it is not only the frog angle that determines the cutting angle, but also the angle of the juncture of the underside of the iron and the upperside bevel. That is why a back bevel (on a bevel down iron) alters the cutting angle of the plane.

With regard back bevels, my understanding of the one that DC advocates in his "ruler trick" is that it is so small (in terms of degrees - what is it 1 or 2 degrees?) that it really does not significantly alter the cutting angle. If, on the other hand, I were to add a significant backbevel to a (say) a Stanley #4 for figured timber, it would require a 10 - 15 degree back bevel to raise the cutting angle from 45- to 55 or 60 degrees.

The use of micro bevels has become important to me of late. For years I just persisted in freehanding flat bevels on my waterstones, absolutely hating sharpening (with the attention span and patience here of a flea). The aim has been to sharpen as quickly as possible, which has led to two realisations:
(1) I can't sharpen micro bevels freehand (so I have returned to using a honing guide in this regard), and
(2) Not all blades require the same standards of sharpness to work well. For example, my chisels are very (very!) sharp but not finished in as high a grits, and therefore not as smooth as my plane blades (where surface finish is important).

I wonder if others agree/disagree with the latter point.

Regards from Perth

Derek

 

[Philly]

Hi All
Just to muddy things a little more... :lol:
When an iron or chisel needs re-sharpening I stroll over to the watersones, pop it in the honing guide at a smidge over the primary bevel and give it 6 wipes on the 800 stone. That normally raises a wire edge. I then alter the guide for a smidge less again and give it 6 wipes on the 6000 stone. Remove the guide, wipe the back on the 6000 and oil the blade. Then get back to work.
That is how I re-sharpen IF it is blunt. If there is a chip or serious ding well you need to re-gring the primary (25 degree) bevel and then hone.
This is along the lines of DC's method and only takes a minute to hone a razor edge.
The wire edge is evidence that you have sharpened right to the tip of the blade-if you dont feel a wire edge, when you hone the secondary bevel you are goingto be there a long time!
Is this any help JS?
Cheers
Philly

 

[Anonymous]

Bevels only change the way the blade cuts on bevel-up irons - on bevel down, the characteristic of the cut is defined by the frog, with the bevel only really controlling sharpness versus edge longevity.

ES, that is a nice way of summarising the interaction between blade bevel and bed/frog. I fully agree with you for the bevel up irons, but you have omitted a factor for the bevel down setup. With the latter it is not only the frog angle that determines the cutting angle, but also the angle of the juncture of the underside of the iron and the upperside bevel. That is why a back bevel (on a bevel down iron) alters the cutting angle of the plane.

Yep, I didn't want to muddy things by getting into back bevels

 

[Alf]

Right, whoa, let's back up a bit. I have no quibble with anyone's ideas on using two bevels, it's simplicity itself, but I think further clarification is needed on this third bevel business. Hopefully it'll explain it better this time. Wish I still had the DVD... :roll:

Firstly, like the Ruler Trick, it's one of DC's "things" and as such is either a) A total waste of time purely generated to give him something to write about and for everyone to go "ooo, how daring" :wink: or b) there's a point to it in which case following exactly what he does would seem to be a good idea until you understand enough to either i) dismiss it or ii) not question it anyway 'cos it's blindingly obvious why you should do it. The Ruler Trick is to cut down the polishing step for the back of the blades, and as I understand it, the third bevel is for the same reasons - just on the bevel rather than the back. Sooo, either you do the secondary bevel in a lower grit to raise a wire edge and then polish with a slightly higher third bevel or there's no blinking point in having a third bevel at all. And this highlights my personal quibble with the DVD - not enough whys and wherefores, too much "just do as I say" stuff. Tsk. :roll: :wink:

Does that make any sense? If any dwellers in North Devon with beards would like to delurk and clear this up I'd be obliged and will slink away suitably embarrassed.

Cheers, Alf

 

[J.A.S]

Alf,

I checked DC's sharpening tape last night, and found that he does exactly what you describe:

you do the secondary bevel in a lower grit to raise a wire edge and then polish with a slightly higher third bevel

Thus, having three bevels does, indeed, make sense.

Philly, your suggestions are similarly helpful.

I agree with other comments about the 'Ruler trick': it doesn't create a back bevel in any useful sense (the angle's far too small); it's simply a great way to make it much easier to polish the iron's back. It's worth emphasizing that a chisel shouldn't be allowed even to watch the trick being performed :wink: .

Jeremy

 

[Frank D.]

Interesting discussion.
Never mind what I said earlier about the angle affecting the way a blade behaves, I didn't mean it affected the angle of attack and didn't express myself correctly (brain fart induced by too many bevels).
I remember reading somewhere that Charlesworth does use a back bevel only to speed up polishing of the back. If you wanted a 5° back bevel (which would give you a York pitch on a 45° bench plane) you'd need a 1/8" (3mm) support, 1 1/2" from the edge, which is much more support than what a little ruler provides.
As to the theird bevel, if it helps some people more power to them, but I find that, after making a primary bevel, the secondary bevel only takes about 10 strokes on my 4000 stone, then about the same on my 8000 for the final polish--not a very time consuming activity. I'd suspect that finding the angle for the third bevel, even if it's just the time to turn the little knob on the Veritas jig) would take at least as long.
Sorry for any confusion which I may have spread,
Frank D.

 

[J.A.S]

Sorry for any confusion which I may have spread

I'm the only one who could be guilty of that, Frank! Besides, it wouldn't have become an interesting discussion without so many comments.

Jeremy