One Bevel, Two Bevels, Three Bevels, More?

[Benchwayze]

Not wishing to hijack other threads, I'm curious as the the advantages/disadvantages of having differing numbers of bevels on your blades. I've only ever honed a single bevel on my plane irons and chisels and find it works for me. So, why are there variations? How does it make a difference to performance?

The reality of grinding at 25* and honing at 30* is that often in the heat of battle with lots of quick rehonings the 30* angle grows and becomes multiple bevels to boot - sort of a mess as anybody who has every bought a vintage tool can surely attest to. One lifts ever so slightly higher at each rehoning in order to produce a burr in a hurry. You can just go ahead and round it under and you'll save time and steel in the long run. This is the Paul Sellers/Jacob Butler/many past woodworkers lost to history technique. Or, alternatively, hone it on the grinding bevel with no lift - grind it at 30* and register the hollow ground edge to the stone and do not lift to put a micro on it at all. Everything happens at 30*

Everything happens at the point where the face meets the bevel, at 'zero'. A theoretical impossibility I suppose, as there is always going to be a micro edge that isn't touched by the stone. The bigger that 'round over' (the shiny line, not to be confused with the rounded bevel) the more blunt is the iron.

It's like asking how many times can you halve the distance between a chair and the wall. In theory the two would never touch, because there's always going to be a distance that can be halved.

Am I gibbering? :mrgreen: .

And MM, re sharpening!! I told you didden I! :lol: :lol: :lol:

 

[Cheshirechappie]

At the risk of upsetting MMUK even more, a bit of background information about grindstones.

In the book 'Tools for the Job' (revised edition 1986, HMSO) LTC Rolt (possibly the finest ever writer on matters of engineering history) states that the first example of a rotary grindstone is recorded in the Utrecht Psalter of AD850, and given the scarcity of documents from around that time, the invention of the machine almost certainly predates that. The illustration in the Psalter shows a vertical wheel about 5 feet in diameter on a horizontal shaft, driven by hand with a crank handle by one operator, whilst the other sits astride a board applying the work (a sword) to the top of the stone using both hands to apply pressure and control the workpiece. It's precisely the same arrangement used by the Sheffield grinders (except for the hand cranking) 1000 years later.

Grinding wheels have been around for a very long time. They are very 'trad'.

 

[Benchwayze]

I don't think MMUK was disputing anything. He just asked a question. (which I'm not quite sure has been answered fully.) That it was a sharpening question is by the by... It's developing into another this-way-that-way sharpening thread......

 

[Corneel]

The question was answered on the first page allready. If MMUK has still more questions about the subject, he should ask them.

 

[bugbear]

The question was answered on the first page allready. If MMUK has still more questions about the subject, he should ask them.

The forum canna' take it, cap'n !

BugBear

 

[Benchwayze]

The question was answered on the first page allready. If MMUK has still more questions about the subject, he should ask them.

The forum canna' take it, cap'n !

BugBear

Aye mebbe, but there be more than one reason for a double bevel. 8)

 

[David C]

The advantages of three bevels are speed and efficiency.

Where large amounts of metal are to be removed, this is done on the grinder, not a coarse stone. Say 23 to 25 degrees.

The coarse stone is used to get a small wire edge. Perhaps 28, 30 or 33 degrees.

The coarse stone angle is raised by approximately 2 degrees. This usually means shortening Eclipse projection by roughly a couple of mm, no need to measure this.

The tip of the coarse stone bevel is now polished on a (6,8, or 10,000 grit stone). This only takes 3 or four gently caressing strokes.

Back, wire edge polished off as usual, no stropping required.

We see that the polishing stone does very little work at all. The coarse (perhaps 800 stone) does enough strokes to form a small wire edge. The number of strokes increases, with each sharpening, till a regrind is necessary. Straight after a regrind this might be as little as 2 or 3 strokes. I reckon to get about 7 sharpenings between grinds.

Unlike C Stanford's scenario, I do not get multiple bevels, because my angles do not change. I use an Eclipse guide. Simple, cheap, quick, accurate and repeatable, it does both straight, square and cambered blades.

I believe I use less strokes than some use for stropping.

Best wishes,
David Charlesworth

 

[Trafalgar]

If one uses a guide I see no real reason not to simply have one bevel. This is especially true with an Eclipse since there is no facility inherent in the jig itself to produce a secondary bevel. One would have to loosen the cutter and reduce the projection of the iron.

With an Eclipse one can raise a wire edge on a medium stone in four or five strokes and then polish it off on one's finest media. Planecraft asserts, probably quite rightly, that the one-bevel method results in a "sweeter" cutting tool anyway (and this assertion is made in context with using a jig for honing). This same advice can also be found in Joyce. With these two sources I"m not sure how much more unimpeachable one can get. It seems to me what both of these classic sources are saying that if you choose to use a jig *in the first place* then make it no more complicated than it needs to be - just hone on the primary.

I use an Eclipse regularly on two cutters - one in my Record 778 and a Record Jack Rabbet. I initially ground these irons on low grit sandpaper using the jig and in subsequent years just go back to a medium India and Black Arky for honing. There have been no re-grindings, hand powered or otherwise, in years.

I am not aware of one, single, classic reference on the craft that mentions the *purposeful* production of three bevels on any cutting edge on any tool used in woodworking for any reason, speed of honing or otherwise. I personally cannot imagine something more maddening than maintaining three bevels (whose widths must be measured practically in angstroms) on a cutting edge.

 

[Jacob]

Well yes and if you must use a jig there is no need for sequences of bevels as with each pass you shorten and tilt the blade forwards by a tiny amount, on to the edge.
In fact if you use a jig for long enough initially set at say 25º, without adjusting it, it will produce a rounded bevel.
Do the same freehand - much quicker without the jig.

 

[David C]

Of course there are no classic references, because I figured it out for myself.

The third bevel just means one polishes a smaller area of metal, with fewer strokes.

It is likely that Joyce and Hampton used strops as a final stage. Even a hard black Arkansas stone is nowhere near as fine as a 10,000 grit waterstone.

These things really don't matter much, people choose the method that suits them. I was just attempting an answer to the "why three bevels" question.

David

 

[Jacob]

... Even a hard black Arkansas stone is nowhere near as fine as a 10,000 grit waterstone.....

Yebbut the Arkansas is fine enough for any woodworker (too fine for most) and will last for life and won't ever need flattening.
I'm mystified by the fashion for waterstones - so obviously impractical, and expensive.

 

[Cheshirechappie]

I'm mystified by the fashion for waterstones - so obviously impractical, and expensive.

The Japanese might be mystified by that comment, too. They've been using waterstones for centuries - very 'trad' in Japan, are waterstones.

 

[David C]

8" x 2" x 1/2" Translucent Ark £82-98.

8" x 3" x 1" Black Ark £183-80.

I found Larry Williams technique very interesting. Three oil stones which he flattens with a diamond stone, every sharpening.

It's all these ####### hollow stones which we have to thank for the apalling old bellied chisels and plane blades out there.

David

 

[Trafalgar]

Of course there are no classic references, because I figured it out for myself.

The third bevel just means one polishes a smaller area of metal, with fewer strokes.

It is likely that Joyce and Hampton used strops as a final stage. Even a hard black Arkansas stone is nowhere near as fine as a 10,000 grit waterstone.

These things really don't matter much, people choose the method that suits them. I was just attempting an answer to the "why three bevels" question.

David

Then again a relevant question might be "why am I the only guy who seems to be using three (intentional) bevels?" Four including a back bevel.

Do you really find that maintaining sharp edges requires all this fuss -- three bevels plus a back bevel? At what point would it become absurd even for you? What is so magical about three bevels? Why not four on the front and two tiny backbevels on the back. Could Nirvana be a couple more bevels away?

Honestly David, I'm trying to picture what it must look like working up three bevels plus a back bevel (and maintaining all four in their proper, respective relationships, sizes, etc.) and then subsequently having the audacity to assert that somehow this saves time? It's hard to come away from the contention of the propriety of using four bevels that some sort of obsession isn't in play.

Apologies for being stunned by it all. Surely, I can't be the only one who thinks this to be more than just a touch over the top.

 

[MMUK]

I must be a proper cheapskate then. I use a piece of granite salvaged from a broken inspection table and wet/dry paper :lol:

 

[MIGNAL]

You certainly don't need 3 bevels :shock: Even with an 8,000G waterstone you can grind a micro bevel in seconds straight from a 100G hand crank stone. I know, I used the method for years.

 

[David C]

Charles,

I'm so sorry to hear that you are struggling with these simple concepts.

Coarse stone to raise wire edge, polishing stone to replace stropping.

I do hope you are not putting back bevels on your chisels?

David

 

[Jacob]

ooh dear Dave going sarcastic again!

All in all I see this thread as a very convincing argument for getting back to basics i.e. freehand with an oil stone or two, and a leather strop if you want super dooper sharp.
Otherwise it'll do yer ed in, not to mention your bank balance and wasting a lot of time. You have to set aside just a little time for some woodwork!
Modern sharpening has departed from reality, gone stratospheric and is well on the way to Mars!
Good for a laugh though. :lol: :lol:

 

[iNewbie]

ooh dear Dave going sarcastic again!

Ooh the Irony again! :mrgreen:

 

[bugbear]

In fact if you use a jig for long enough initially set at say 25º, without adjusting it, it will produce a rounded bevel.

At what stage when working a flat bevel on a flat stone does the roundness happen?

The removal of metal at each sharpening when using a jig is small, certainly not enough to alter
the angle.

So (as almost everyone knows) the bevel
when using a jig stays flat, and is the same angle each time. SImple.

Or was your claim more "exaggerration" ?

On the other hand, your claim that people find jigs confusing seems to be true for at least one person. :lol:

BugBear