# Chisel backs



## Corneel (25 Aug 2013)

Some philosofing and a bit of experience with vintage chisels, made me start a thread on chisel backs. I am especially interested in how these theories can be used in practice to reduce the amount of work to bring an old one back in shape and use it with pleasure.





The ideal shape of a chisel has a flat back. Ideal, but hard to get in practice. But in use when paring wood this should work very nice. Light pressure on the tip and the chisel starts to cut. Also when registring the chisel from a reference surface this should be ideal, but I don't think that is a very common occurence in woodworking. A question with this shape is, how to keep it flat over time?






The concave back. This is often regarded to be ideal too. At least it is easy to sharpen. And over time it will tend to become flatter, which is more ideal probably. But in paring it might be a bit grabby? Tend to dive into the wood too easy?






The convex back. Often regarded with dismay, but very common in the field. If the belly isn't too bad, how awfull can this be? It makes for a chisel which is easy to stear in the wood. Also sharpening this isn't difficult as long as you keep fingerpressure on the edge. Over time it will tend to become rounder, not flatter.






The true backbevel. This is probably something to avoid. The chisel doesn't want to cut when paring. Sharpening is also difficult.



And then something about wear and sharpening. An edge wears round, thus creating a wearbevel both on the front and the back. 



Usual practice is grinding back the bevel until you get a wire edge. That means grinding back to the red line which removes both wear bevels. Then just a light polishing wipe on the back to remove the wire edge. At the other hand, what if you want to avoid this scenario and give a quick hone often, what do you do exactly to avoid a backbevel?

Personally I'm not afraid for a heated argument but please try to remain civil to each other. My ideas in this are far from set in stone. I hope to learn something from the collective wisdom.


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## woodbrains (25 Aug 2013)

Hello,

A lot of this makes sense and the bits about back bevel and wear bevel you describe, are pretty much exactly as I was saying in the other thread, but as I also pointed out, someone's mission was to always contradict me, no matter what. It just becomes exasperating for me, so good luck here.

I would say that the concave back illustration is a longitudinal section and therefore the chisel is hollow in both dimensions, rather like a Japanese chisel, rather than just a banana shape? Am I right. If so, the chisel would not be grabby, as the sides would contact the work and it would act no differently to a chisel with a flat back. A banana shape would be terrible.

Paring to a reference surface is done quite a lot in dovetailing, and other paring tasks for fine fitting joint making, so I would always avoid the convex back. I don't think it is worth getting a lovely cast steel chisel, especially if it is for little money, and not bringing it up to the best working standard it could be. It takes workto get them flat, but not a prohibitive amount. The drawing is an exaggeration, I've not come across a chisel out by more than ( estimating ) about 10 thou. Most are much less and flatten on coarse wet and dry in minutes.

Mike.


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## Corneel (25 Aug 2013)

Indeed, pictures are exagerated.

I have a small set of Japanese chisels and they are by far the best chisels I have. Totally flat on the back (with the hollow of course), easy to sharpen but a very long lasting edge. They are quite ideal, but rather short, which sometimes is not helpfull. And expensive of course.

I also have two very long Sorby paring chisels which are definitely banana shape. You can bend them though, so it isn't too hard to press them flat on a surface. I am not sure yet what to do with them.

And then I have a fairly large accumulation of Dutch, Swedish and English chisels, most are more or less convex. I use them often, also for paring duties and don't find the convexity to be very problematic. 

I'n mot quite sure how you use a reference surface when dovetailing? As far as I can see it is mostly a freehand excercise. Also for example when cleaning up a halflap joint after the initial chopping. All the surface is rough, so there is no reference. I then work from both sides inwards, without reference either, probably leaving a bulge in the middle, sloping down to the sides. No reference to speak of. I'm just lying the back flat on the wood and work on the bulge until I shoot out on the other side. A convexity doesn't hinder this aproach. The only reference surface I can think of is with a guide, for example when paring the bed of a plane using a beveled block clamped to the top as a guide.


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## Corneel (25 Aug 2013)

Oh, and I don't know why we can't get coarse sandpaper overhere that makes leveling chisel backs a matter of minutes. :evil: 

In the past I've spend hours on a single chisel. Especially when going from the sandpaper to the stones, I always seem to have created a convexity.


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## Jacob (25 Aug 2013)

Theorising is interesting (I suppose :roll: )but it can get in the way of the work especially if you are driven in the direction of flattening and polishing everything!
But in reality any sharp edge will work but the different configurations (bellied, back bevelled, flat, concave etc) might entail small variation in technique which would be more or less unconscious. You might also be altering your sharpening technique, without giving it much thought.
There is only issue if a particular shape is definitely causing a problem in which case you either pick up another chisel or reshape the one you are using.
In reality a chisel would have to be very concave to make "paring to a reference surface" a problem. You can see the logic of it ( that's the trouble with armchair theorising!) but who has encountered this in a real working situation? I certainly haven't and a lot of my chisels are vaguely concave on the face - including nice old ones. IMO flattening them spoils them and makes sharpening more difficult.
In any case it is logically difficult to "pare to a reference surface" as you are altering the surface as you go and directing the tool as you want. Chicken and egg - you can't have a reference surface unless you pare to it, starting from a position without a reference surface. Erewego, armchair theorising has no limit!


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## woodbrains (25 Aug 2013)

Hello,

OK you rumbled me, I just theorise from the comfort of my armchair. Here are some of my theoretical dovetails in some of my theoretical furniture.

I really cannot understand the want of some here to try and circumvent doing what is necessary to get a tool sharp and well fettled. I cannot think of anything in life that benefits by missing out steps and pretending the result is just the same. Why waste time thinking up new and novel ways of not doing what is necessary, my tools work; if they were not sharp they wouldn't, nor flat backed, nor have fine bevels etc. And if my tools work, why wouldn't I tell others what I have found to work best.

Mike.


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## Corneel (25 Aug 2013)

Just been looking at my Sorby parers. The wide one is in fact not bad at all. It has a hollow in the back with the front and the sides in one plane for several inches up the face. The narrow one isn't so good, it is definitely more banana shaped.

Mike, I still wonder exactly where the reference is when making dovetails? 

And why don't I want to make the chisels totally flat? Because of the work involved.

Nice work BTW.


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## Jacob (25 Aug 2013)

woodbrains":yrud88wr said:


> Hello,
> 
> OK you rumbled me, I just theorise from the comfort of my armchair. Here are some of my theoretical dovetails in some of my theoretical furniture.


Very neat. Mind you I'm not too keen on that irregular spacing - I know it's fashionable (everybody's doing it :roll: ) but it just looks a bit untidy to me. Also I prefer the single kerf triangle (sometimes called London Pattern for no apparent reason) rather then the fat ended trapezium. And it's easier. I guess you are obeying the arbitrary rule of a gradient of 1/8
Here's some of mine






> I really cannot understand the want of some here to try and circumvent doing what is necessary to get a tool sharp and well fettled.


Because it doesn't seem to be necessary to th extent which is fashionable nowadays.


> I cannot think of anything in life that benefits by missing out steps and pretending the result is just the same. Why waste time thinking up new and novel ways of not doing what is necessary, my tools work; if they were not sharp they wouldn't, nor flat backed, nor have fine bevels etc. And if my tools work, why wouldn't I tell others what I have found to work best.
> 
> Mike.


I'm sure they work but I think you probably spend too much time doing unnecessary things in the way of flattening, polishing etc. not to mention the struggle with honing jigs and buying unnecessarily expensive tools. :lol:


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## Corneel (25 Aug 2013)

Show offs!


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## woodbrains (25 Aug 2013)

Hello,

I did actually write a longish reply to Corneel's questions, but it seemed to disappear when I presented submit, might do again later, if I have time.

When I do dovetails, I choose assymetrical ones ( not irregular spacing!) for constructional soundness, not fashion. If a board is going to cup, it can perhaps let go along the edges. Spacing the dovetails so there are more towards the edges helps with resisting any cupping of the board. Of course it might not, but I'm not going to be here in 100 years to witness it. I try to build longevity into my work, central heating puts a lot more stress on furniture than would be seen even 30 years ago and available wood is not as stable as Cuban mahogany, either.

London pattern dovetails are nice, but not for carcasses. 

There are about 13 individual tails per edge on the carcass in one of the photos. (More than 50 coming together all at once.) I do not want a tool that will not behave and do something I cannot predict or have to make allowances for as one over cut will ruin the whole set. Once the chisel backs are flat, they are done forever and I can always rely on them.

Corneel's, in half blnds, the pins are partially cut with a saw and this provides a reference surface for the chisel to continue the pin socket into the corners. There are others, if you think about it, even holding the chisel vertical to make a chopping cut at the baseline will not be possible if the chisel is convex or has a back bevel. Once the first chop here establishes a flat and vertical face, it serves as a reference for continuing the cuts. It is much harder to cut a flat surface with a non flat chisel.

Mike.


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## woodbrains (25 Aug 2013)

Oh and do they look like one in eight to you?

Mike.


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## G S Haydon (25 Aug 2013)

First off, compliments to those showing the quality work. Both examples are very well executed indeed =D> 

Also, I do not want to change how anyone prepares their tools or claim their methods are no good or what I think is best.

Ok, so until I started looking at forums (feb this year) all I had ever done was sharpening. This concept of flatness was all new, I felt quite ignorant. I bought a cheap set of chisels and took some time to flatten the backs a little. I did not fully flatten them because I was too lazy. Reflecting on this approach I wish I had not bothered for what is a general purpose set of chisels. Every single one of those cheapies had a slightly hollow back. Perhaps a 12mm flat behind the blade would be more than enough for the type of work I do. The really nice thing about the hollow back is that it focuses the honing when removing the burr, and it would seem speeds up removing the wear bevel.
I very much like this article on the subject. http://www.toolsforworkingwood.com/store/blog/243

I have never back beveled a chisel.

I don't think I have never used a convex bellied chisel. I think you could use one, cant say really if I have never tried.

Each to their own


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## Corneel (25 Aug 2013)

I see what you mean Mike. But that's only a very short bit, 3/8" I suppose in a carcasse, I suppose? Even with a convexity all the way to the edge you can pair into the corner and steer the chisel wherever you want it. My bellied chisels actually have a bit of flat on the front, about 3/8 I guess, so that would take care of this issue. Anyway, I am in no hurry to start flattening the backs of these chisels, until I find a situation where I really need a flat back.

Backbevels on a chisel seem to be unwise, so I understand why you won't want to strop this side.

Nice article G.S. Joel sounds pretty rational in that article.


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## Jacob (25 Aug 2013)

woodbrains":2n3iafl2 said:


> ...... It is much harder to cut a flat surface with a non flat chisel.
> 
> Mike.


In the ordinary way of things they are never so non flat that you couldn't cut a DT as you describe and in any case a concave curve would conveniently undercut and make a better dovetail!
Come to think a lot of shoulders need undercutting - a purpose made under cutting chisel could be good - I'm surprised nobody has thought of this, I'd buy a complete set (with PMT69 steel and bubinga handles) immediately!
Mind you it could be done with a convex faced chisel (within reason) with no difficulty at all.


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## David C (25 Aug 2013)

One of the worst aspects of the bellied chisel, is that the wire edge will not be honed away on a fine stone, without some very dodgy handle lifting.

Unless of course the belly exactly matches the hollow of the stone! I suspect this is the cause of convexity on many old tools.

David


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## Corneel (25 Aug 2013)

No problem reaching the wire edge. The secret is putting finger pressure on top of the chisel near the cutting end. So you don't need to do any dodgy handle lifting. From experience I know it is no problem to get the edge sharp.

We are talking very light convexities here, a piece of paper just slips under it. The picture is exagerated of course. It will get worse over time, but I have no idea what timeframe we should think about.


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## Jacob (25 Aug 2013)

David C":1rucydi4 said:


> One of the worst aspects of the bellied chisel, is that the wire edge will not be honed away on a fine stone, without some very dodgy handle lifting.


Well yes but nothing dodgy about it - needs must when devil drives!


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## woodbrains (25 Aug 2013)

Corneel":1bsgm1mg said:


> No problem reaching the wire edge. The secret is putting finger pressure on top of the chisel near the cutting end. So you don't need to do any dodgy handle lifting. From experience I know it is no problem to get the edge sharp.
> 
> We are talking very light convexities here, a piece of paper just slips under it. The picture is exagerated of course. It will get worse over time, but I have no idea what timeframe we should think about.



Hello,

This is where I get confused. If the convex only is slight, how much effort could it be to correct to flat? But if the slight convexity eventually becomes more exaggerated over continued honings, as I agree, it must, surely it is essential to correct the problem early on.

Mike


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## Corneel (25 Aug 2013)

I see your point, but I hate the work. Sitting here on the sofa isn't usefull either, but at least it is pleasant...

I did a bit of calculating. 0.2mm convexity. The chisel is 1.8cm wide and the area about 10cm long. Lets say the shape is triangualr instead of convex. That makes 0.5 x (0.02 x 1.8 x 10) = 0.18 cm2 of hardened toolsteel to be removed with sandpaper. That's a lot!

And as long as it doesn't present real problems and as long as I have other chisels when it really must be flat, I remain lazy.


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## Jacob (25 Aug 2013)

I suppose what I'm suggesting is that you shouldn't look to closely at your chisel. Just sharpen it and get on with whatever you are doing.
If you find there is a problem in spite of all you best efforts then have a closer look.

I had a 7 plane which just wouldn't do a good straight edge however I tried. It turned out to be slightly concave along the length so I put it on ebay and bought another one. Job done! There's no point in looking for problems from the armchair - they'll show soon enough.


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## woodbrains (25 Aug 2013)

Hello,

100% agree that this work is a real pain, it is not as if I like it, either. Never calculated the volume of steel removed before!

Mike.


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## Corneel (25 Aug 2013)

Just went out to the shop (instead of continueing to be lazy). I spend half an hour with an 1/2"chisel on 120 grit sandpaper and had the feeling that I was getting nowhere. All in the name of science! Tomorrow I'll buy some fresh 80 grit, but I won't promiss any updates soon.


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## Jacob (25 Aug 2013)

woodbrains":2cvwjix8 said:


> Hello,
> 
> 100% agree that this work is a real pain, it is not as if I like it, either. .....


Well stop doing it then! If it really is necessary (very unlikely) just get another chisel.


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## woodbrains (25 Aug 2013)

Jacob":1fjfjrsm said:


> woodbrains":1fjfjrsm said:
> 
> 
> > Hello,
> ...



Hello,

All mine are done now :lol: not that they needed much in the first place, I don't buy things new or old that are to bad to begin with.

Mike.


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## Corneel (26 Aug 2013)

In the name of science, I have corrected one of my bellied chisels. This one is 16mm wide and the flat iron bit is something like 11 cm long. Made bij Berg in Sweden. It came to me with a very noticable belly, you could rock it back and forth on a straight edge. I had it flattened and polished an inch or so from the edge. And used it like that for years.

In light of this discussion I glued some strips of 80 grit to a glass plate. Two narrow strips and one full width. I started on the narrow ones to remove the belly (hard to do when sanding all the length of the chisel in one go).




After a while the sanding paper lost its effectiveness. I could have glued a new piece to the glass, but I was impatient and went to the stones. 400, 1000, 4000 and 8000 grit. Carefully flattened of course and making sure all of the stone was equilly used. As usual it takes a lot of time to go from the sandpaper to the stones. Somehow they never match immediately. Overall it took me 2.5 hours to create an ideal chisel. Not too bad, I thought it would have taken longer.





I am not going to give my other chisels the same treatment. I'm pretty sick of it all ready. Some observations:
When someone tells you that it takes a few minutes to flatten a chiselback, don't believe them. (Sorry Mike).
In David Charlesworth's book you can read how he flattens chisel backs, starting with an 800 stone. That must be pure torture with a chisel like this. Start with the coarsest grit you have. 
The sandpaper I can get isn't optimal for steel. I'll ask around here if I can find something better, especially longer lasting. Maybe this is an ideal job for diamonds, but you always only hear about very fine diamonds for polishing, not the coarse ones.
When I started to read the woodworking forums, about 6 years ago, it was very common to see someone showing a picture like this, very proudly. I think times are a changing. You don't see this very often anymore. Most people will advice you to polish half an inch or so. Which I think is great advice.


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## David C (26 Aug 2013)

Ah but Corneel, In the beginning I was advised not to buy bellied chisels, and I paid good attention to this councel. I have sent many many chisels back to the manufacturer or retailer. A correctly ground English chisel has the slight concavity in length which is so beneficial for preparation and sharpening.

By the way, the reason your scrub blade is not working in your guide, is that it is in the chisel slot. My L-N blade fits in the plane blade department.

David Charlesworth


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## Jacob (26 Aug 2013)

David C":36i0yw9d said:


> ..... A correctly ground English chisel has the slight concavity in length which is so beneficial for preparation and sharpening.


Yes and this mean sharpening takes about a minute and you are off. 
If they need "preparation" they should be sent back - it's the tool maker's job, they have got all the kit. 
Unfortunately, due to the great mass of misleading information around this topic, innocent beginners are buying top class tools, wasting hours of time and spoiling them by "prepping" them. "Prepping" - stupid name, stupid idea!
flattening-chisel-backs-with-lapping-film-t68506-225.html

This is as much flattening and polishing you need on a typical new chisel face:







And this chisel would be perfectly flat enough for woodbrain's half blind DT paring problem, even though it is convex by about 1.5mm in the middle


> By the way, the reason your scrub blade is not working in your guide, is that it is in the chisel slot. My L-N blade fits in the plane blade department.
> 
> David Charlesworth


Too narrow for the plane slot and much easier freehand anyway. Why struggle? Is it possible to do a scrub plane blade in a jig anyway, bearing in mind it has to be turned through quite an angle to get the camber?
Just because you have got a jig doesn't mean you _have_ to use it! Try it without training wheels!


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## Cheshirechappie (26 Aug 2013)

I think Ashley Iles aim for about 3 to 5 thou concave on their b/e chisel flat faces. I'd have said that 1.5mm (1/16", about 0.060") is a bit too much concavity on a chisel expected to do good class work. 

How fussy you are about flat face flatness depends what you want the chisel to do. For really rough work, 1/16" might well be acceptable. For fine cabinetmaking and similar precision work, the AI concavity seems to me to be more appropriate.

I'd say the same about a belly in the flat face, too. Preferably none at all for fine work, but for rough carpentry a bit of bellying could be acceptable. 

In the end, however, it's the results that count. If the chisel does what you want it to, easily and without needing undue manipulation, it's in good enough order. The only time to worry about chisel flat face flatness is when the chisel won't do what you want it to. The moral of this story is - when you aquire new chisels, be they brand new or vintage, sharpen them up and test them out before you spend time on correcting faults that may be immaterial.

Aiming for optical degrees of flatness just seems pointless for any woodworking task, however precise. I suppose it wouldn't do much harm, but it's hard to see how it would be beneficial, either. After all, wood will 'give' a bit as it's being worked, and will move a bit with climatic conditions over time. Treating wood like a high precision grade of toolsteel suitable for gauge-making really is pointless.


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## Jacob (26 Aug 2013)

Cheshirechappie":2gr4dpkc said:


> I think Ashley Iles aim for about 3 to 5 thou concave on their b/e chisel flat faces. I'd have said that 1.5mm (1/16", about 0.060") is a bit too much concavity on a chisel expected to do good class work.


Why? I keep asking this but nobody ever answers! 1.5mm in the length of a chisel is getting on for 0.1mm in the end few mm which is reduced again by flattening (see photo above) which is doing the work. And what is the problem with "belly" exactly? All chisels will end up slightly less than concave - should we bin them? I think not.


> .... The moral of this story is - when you aquire new chisels, be they brand new or vintage, sharpen them up and test them out before you spend time on correcting faults that may be immaterial..... Treating wood like a high precision grade of toolsteel suitable for gauge-making really is pointless.


Definitely!


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## woodbrains (26 Aug 2013)

Hello,

Wow, Corneel 2 1/2 hours on the back of a chisel. I'm sorry if I encouraged you to do this, but I have never in my life spent even close to that sort of time. I can only conclude that it must have been a dog of a tool. Maybe it was misused and bent, perhaps, to need so much work. If it was as far out as this amount of time would suggest, then it couldn't have been much use, so take some gratification that yo have produced a workable tool from a relative junker.

I once had a 5 jack plane that had 10 thou needing removing from the entire sole, but even that did not take 2 1/2 hours. Hats off to you for perseverence! =D> 

Mike.


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## Paul Chapman (26 Aug 2013)

Jacob":1m580gql said:


> Is it possible to do a scrub plane blade in a jig anyway, bearing in mind it has to be turned through quite an angle to get the camber?



As I said before, I can't understand why you feel it necessary to hone the whole of the camber on a scrub plane. Just checked mine and I hone a central portion which amounts to about half the camber. I can't imagine that you ever have anywhere near the whole of the camber projecting when using the plane.

Must be quite entertaining watching you freehand hone the camber at the same time as maintaining a rounded bevel - all at the speed of light, of course  

Cheers :wink: 

Paul


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## Corneel (26 Aug 2013)

woodbrains":32juek85 said:


> Hello,
> 
> Wow, Corneel 2 1/2 hours on the back of a chisel. I'm sorry if I encouraged you to do this, but I have never in my life spent even close to that sort of time. I can only conclude that it must have been a dog of a tool. Maybe it was misused and bent, perhaps, to need so much work. If it was as far out as this amount of time would suggest, then it couldn't have been much use, so take some gratification that yo have produced a workable tool from a relative junker.
> 
> ...



Well, in that case I'd like to see some tips! Maybe it's the sandpaper, I use 3M sandblaster, whatever that is, they don't tell on the package. I feel it really wears out too soon on metal. Like I said, I need to find something aimed at the metalworker. Another point, it always takes me a long time to go from the sandpaper to the stones. If it looks perfect after the sandpaper, I usually only get around half of the surface on my 400 stone. So that takes considerable time. As soon as it is fine on the 400 stone, it doesn't take too long anymore on the rest of the stones.

The chisel had a convexity about 0.2mm. Meassured with a piece of paper. One paper easilly slipped under the chisel, 2 didn't, and the paper was 0.15mm thick. So it wasn't terible, just obviously convex and I have used it a lot. This chiselset was my only set for quite some time. There are more with various amounts of convexity.

When buying new chisels it's easy. They should look like the picture from Jacob. But I like to buy old ones, and many old chisels are convex like this. Jt makes you wonder, didn't they care at all, back in the day?

And don't worry about this little experiment. It was fun, in a perverse kind of way.


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## Corneel (26 Aug 2013)

David C":1uqqachi said:


> Ah but Corneel, In the beginning I was advised not to buy bellied chisels, and I paid good attention to this councel. I have sent many many chisels back to the manufacturer or retailer. A correctly ground English chisel has the slight concavity in length which is so beneficial for preparation and sharpening.
> 
> By the way, the reason your scrub blade is not working in your guide, is that it is in the chisel slot. My L-N blade fits in the plane blade department.
> 
> David Charlesworth



Ah yes, the new chisels. But I like vintage stuff.

And indeed, the scrub plane blade was too narrow. Which kind of proves my little theory that not every tool fits in a jig. I'm sure you can find something in your shop too.

Moulding planes don't fit in a jig either.





http://pegsandtails.wordpress.com/2009/11/10/sharpening-a-moulding-plane/


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## G S Haydon (26 Aug 2013)




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## David C (26 Aug 2013)

Jacob,

Please do not be more obtuse than you have to.

Preparation means removing manufacturers scratches and getting a nice fine finish adjacent to the edge.

It probably means grinding and honing the bevel as well.

The fact that a certain curved blade can be done with a cheap jig is a matter of interest to some.

Here are some of your helpful observations on honing guides.

100s of quids for a honing guide.
Plus the usual paraphernalia.
They are jealous because they can't do it.
Maybe they actually don't do a lot?
Fiddling with crazy sharpening techniques.
Wouldn't do a camber either, completely pointless.

I would say singularly missleading.

David


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## woodbrains (27 Aug 2013)

Corneel":170cw2lp said:


> Well, in that case I'd like to see some tips! Maybe it's the sandpaper, I use 3M sandblaster, whatever that is, they don't tell on the package. I feel it really wears out too soon on metal. Like I said, I need to find something aimed at the metalworker. Another point, it always takes me a long time to go from the sandpaper to the stones. If it looks perfect after the sandpaper, I usually only get around half of the surface on my 400 stone. So that takes considerable time. As soon as it is fine on the 400 stone, it doesn't take too long anymore on the rest of the stones.
> 
> The chisel had a convexity about 0.2mm. Meassured with a piece of paper. One paper easilly slipped under the chisel, 2 didn't, and the paper was 0.15mm thick. So it wasn't terible, just obviously convex and I have used it a lot. This chiselset was my only set for quite some time. There are more with various amounts of convexity.
> 
> ...



Hello,

This may be inaccurate, but I'm fairly sure 3M sandblasted is aluminium oxide abrasive. Not the best for metal, and if I recall is for decorators sanding between coats of paint. Whatever, you need silicon carbide abrasive, it holds its aggressiveness much longer. Ali oxide is friable when sanding wood, so must break down very quickly on steel. Also, what stones are you using? Japanese, American and European abrasives are graded differently, so you may be making a too big a leap in abrasive grits when you move from the paper to the stones. This is why I always use microns when I compare abrasives, ( much to Jacob's dismay! But there is a good reason) so there is some weans of parity.

Even if the 3M sandblasted is Si C, it is open coated to help with waste material for sanding paint, there is a lo less abrasive available so will not perform as well, and open coated paper is not needed for the task you require.

Mike.


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## Corneel (27 Aug 2013)

That would explain why it doesn't last very long on metal. I'll search a little further for the right stuff. 

I use Japanese stones. The 400 is from Bester, very agressive stone. But I don't know the grit size.


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## Corneel (27 Aug 2013)

Was sitting in the train so had plenty of time to think a bit more. There is more to grit size then just the number from the comparison charts. Grit breaks down. I'm sure when you keep at it long enpough, you could polish with just a piece of 80 grit. My sandpaper wasn't 80 grit anymore by the time I went to the stone. The 400 stone doesn't have a lot of trouble to remove the scratches from the sandpaper. But there is something else going on. The sandpaper seems to create a different surface in the metal then the stone. Probably because of the way the paper and the glue moves under the pressure.

I also have a Sigma 120 stone, but that is a weird stone. Hard to get it working to my liking. It leaves really deep scratches, it wants to load and clog easilly while it is hard to get clean again.

Anyway, I still do need better sandpaper.


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## Jacob (27 Aug 2013)

It's called "emery" or "wet and dry" paper. As used by metal workers and mechanics, available in motor spares , tool, cycle and DIY shops.
Grit sizes is misleading as there are different materials and different ways of putting them together which makes a big difference to how they perform. I stick to coarsest to finest arranged roughly in apparent order. Unless it is specified you may never know the grit size anyway.


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## Corneel (27 Aug 2013)

Thanks Jacob. I'll find something ussable overhere. Tradenames aren't allways easy to translate in Dutch, which makes it difficult to get the stuff recommended on an English forum. But I'll look around in the kind of places you mention.

There sure is a lot more to grit then the micron size. The shape of the grit, how it is embedded in the carrier and how deep. And how it wears. In man made stuff it is easier to compare, but natural stones behave quite a bit different.


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## Jacob (27 Aug 2013)

David C":9gs0qj1y said:


> Jacob,
> 
> Please do not be more obtuse than you have to.
> 
> ...


Obtuse, moi? Clear as day I thought. :lol: 
These things shouldn't take more than a minute and there is no functional reason for removing manufacturers scratches (within reason, see my link photo above).


> ....
> Here are some of your helpful observations on honing guides.
> 
> 100s of quids for a honing guide.
> ...


Good to see you are getting the idea Dave. It's never too late! What is it ypu find misleading? (only one L BTW).


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## bugbear (27 Aug 2013)

Corneel":34efjtl7 said:


> Thanks Jacob. I'll find something ussable overhere. Tradenames aren't allways easy to translate in Dutch, which makes it difficult to get the stuff recommended on an English forum. But I'll look around in the kind of places you mention.
> 
> There sure is a lot more to grit then the micron size. The shape of the grit, how it is embedded in the carrier and how deep. And how it wears. In man made stuff it is easier to compare, but natural stones behave quite a bit different.



Quite right in all regard; although grit size is probably the most important factor, the other factors play a part.

For hacking away tool steel, I recommend the zirconium belts which the metalwork industry uses.

Norton term it "Zirconia", but I've also seen "Zirconium" and "Zirconium Oxide". Great stuff.

BugBear


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## Corneel (27 Aug 2013)

I'll keep an eye out for Zirconia too.

Anyone experience with diamondplates for this purpose? Something like this iWood plate isn't too expensive:
http://www.toolsfromjapan.com/store...roduct_info&cPath=335_462_463&products_id=852


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## Jacob (27 Aug 2013)

Also most common as Silicon Carbide http://en.wikipedia.org/wiki/Sandpaper

Best for flattening (plane soles in my experience but chisels too if you must) is coarse wet n dry paper flooded with white spirit on a machine table. If the paper is paper backed and flat, the white spirit keeps it down and also helps with the abrasion. For a bigger area you can put pieces edge to edge.
60 grit is all you need really, but it helps to take off the snatchiness with a quick pass over your finest, say 400 grit. This leaves the scratches in place but reduces friction by taking the edge off the scratches. Further polishing is just cosmetic and not necessary.


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## woodbrains (27 Aug 2013)

Corneel":82l2yf54 said:


> That would explain why it doesn't last very long on metal. I'll search a little further for the right stuff.
> 
> I use Japanese stones. The 400 is from Bester, very agressive stone. But I don't know the grit size.



Hello,

Japanese 400 stone is slightly finer than P400 sandpaper in European standard. ( 32 micron compared to 35 ). I don't know what grit paper you were using before you moved to your stone, but I would say that you should not be expecting to remove much metal on a stone like that, just removing scratches from the coarser grit. If you still have some metal to remove, you should still be on coarser grits.

You describe the paper as turning into a finer grit as you progress. This is classic firiability of Ali oxide paper, so I suspect this is what you ar e using. Si C does not break down like Ali Oxide and is harder. It will wear out, but takes longer to do so, and the particles do not reduce in size. So 80 grit remains 80 grit, it just gets less effective as time goes on. As a point of interest, the grains of abrasive are rounder as produce 'U' shaped scratches whereas Ali Oxide is pointy and due to its friability, continues to break down into smaller pointy particles, so the scratch pattern is sharper, and continually getting finer as you progress. It doesn't make much practcal difference, but this is what happens. Ali Oxide is less useful for metal.

Mike.


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## Corneel (27 Aug 2013)

You are right of course. But that still leaves me with the problem of mismatch between the surface grinded on the sandpaper and the surface the stone wants to grind. Nobody else have this problem? I like restoring old tools, grinding out pitted backs is a common occurence for me. Yet I haven't found yet a system that makes it a quick and easy job.


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## woodbrains (27 Aug 2013)

Hello,

Go on to finer grits on the sandpaper before the stone. I f you used P 320 as a final paper then 400 stone so the leap in grits is small.

Mike.


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## bugbear (28 Aug 2013)

woodbrains":36u5td0f said:


> Hello,
> 
> Go on to finer grits on the sandpaper before the stone. I f you used P 320 as a final paper then 400 stone so the leap in grits is small.
> 
> Mike.



These list are VERY helpful:

http://sharpeningmadeeasy.com/grits.htm
http://www.metalclayuk.co.uk/asp/MicronsGrits.asp
http://www.fine-tools.com/G10019.htm
http://www.evenfallstudios.com/metrolog ... isons.html

Especially if you mix your abrasives (diamond, waterstones, SiC paper etc)

As discussed elsewhere, grit size is not the only factor, but it's the dominant factor.

BugBear


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## Corneel (28 Aug 2013)

Bugbear, At the end of your first link, there is another link to a very interesting chart. 
http://sharpeningmadeeasy.com/speed.htm
I suppose this graph is about stones? SiC is A carborundum stone probably, AlOx an India stone? Even a 1000 grit waterstone seems to be faster then any carborunmdum stone.


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## Jacob (28 Aug 2013)

I'd be fairly sceptical of graphs like this one. Knife sharpeners are even madder than woodwork tool sharpeners and even more awash with pseudo science.


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## bugbear (28 Aug 2013)

Corneel":3cqmw6ia said:


> Bugbear, At the end of your first link, there is another link to a very interesting chart.
> http://sharpeningmadeeasy.com/speed.htm
> I suppose this graph is about stones? SiC is A carborundum stone probably, AlOx an India stone? Even a 1000 grit waterstone seems to be faster then any carborunmdum stone.



Yes - "Crystolon" from Norton is SiC whilst "India" is AlOx.

BugBear


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## Corneel (28 Aug 2013)

Jacob":790n3im7 said:


> I'd be fairly sceptical of graphs like this one. Knife sharpeners are even madder than woodwork tool sharpeners and even more awash with pseudo science.



I'm not so sure. Maybe not the exact numbers, but my 400 Bester waterstone is definitely way faster then the Carborundum stone or the coarse India I have. So the trend this graph indicates isn't totally hogwash. Keeping the stones clean helps, but still...

You pay for this speed, but as long as I'm not on the dole, I don't really care.


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## woodbrains (28 Aug 2013)

Jacob":2dhb4qj5 said:


> I'd be fairly sceptical of graphs like this one. Knife sharpeners are even madder than woodwork tool sharpeners and even more awash with pseudo science.



Hello,

This graph looks pretty much spot on to me, having used most of the media shown, I would pretty much agree with everything. It is pretty much universally recognised that artificial Japanese waterstones have the greatest speed of cutting and the finest finish, when used in the right combination.

Mike.


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## custard (28 Aug 2013)

I sometimes think we play at being scientific and objective when it comes to sharpening, but we can't actually break away from an almost superstitious "shiny equals sharp" mindset. 

In an effort to get away from the need to constantly flatten water stones I tried using DMT diamond stones. I used a Red (600 mesh/25 micron) and a Tan (8000 mesh/3 micron). 

The problem was the 3 micron stone didn't produce a polished bevel, I tried it with a variety of plane blades and in all honesty found it very difficult to tell if it was less sharp in actual usage than a polished water stone edge, but for the life of me I could never bring myself to lay the backs of my chisels onto the 3 micron diamond stones, knowing it would eradicate the mirror polish. So I went back to water stones! 

Logic tells me that the vast majority of the sharpening fetish is just hocus pocus, and that in practise any amazing edge breaks down in just a few strokes of the tool and you then settle down to 90% of the usage life until the next sharpening being at the "acceptably dull" level rather than the initial "scalpel sharp" level. But logic flies straight out of the window when I'm trying to deliver a flawlessly dovetailed drawer, I become as superstitious as a fisherman and want the comfort blanket of the mirror edge. 

On a related point I strongly suspect that stropping actually dubs over an edge and is a retrograde step, but stropping will always have supporters when "shiny equals sharp" is actually the real litmus test that we're all secretly applying.


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## woodbrains (28 Aug 2013)

Hello,

Dear Custard, what grade of waterstone were you using? Diamond plates when new are pretty aggressive, but settle down to less aggressive and 'softer' edged, so probably would do more like you were expecting after some use. However, 8000 Japanese waterstones are finer, so might account for the different level of polish expected, too. As I said earlier American and Japanese systems are not directly comparable.

Stropping really only has a benefit for oilstone users, as the finest stones are coarser than the finest Waterstones. I don't think the edge is dubbed exactly, but the effective angle is increased and by the nature of the soft strop, the very tip is slightly convex, which makes it look like it is dubbed. Polish is still an abrading excersise, just that the scratches ar finer and not as easy to see, reflecting more direct light, rather than scattering it.

Edges sharpened with finer grits do last longer as the grains of the steel are less fractured to start with and therefore do not crumble so quickly. 

Mike.


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## Jacob (28 Aug 2013)

custard":vnwdgbnv said:


> ....."shiny equals sharp" i.....


More importantly, shiny means less friction - where it counts and there is a lot of pressure on the steel from either side of the cut close to the edge.



woodbrane":vnwdgbnv said:


> ....Stropping really only has a benefit for oilstone users, as the finest stones are coarser than the finest Waterstones.....


There is no particular limit on the fineness of stones you can put oil on.
Stropping is for polish (see above) with the advantage that the flexibility of the leather reaches more of the blade. Without stropping - if the shape of a blade doesn't exactly match a stone then you won't get a thorough polish - hence the obsession with flatness. No different from polishing a brass letter plate - if you did it with Brasso on a piece of wood it wouldn't reach into the dips


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## custard (28 Aug 2013)

woodbrains":2djfk905 said:


> what grade of waterstone were you using?
> 
> Mike.



I generally use Shapton stones, I have them in 1000, 4000, 8000, 15000, and 30000 grits. Which raises an interesting point that I think supports my "shiny equals sharp" sceptics view.

Edges begin to look polished to our eyes at about 8,000 grit. And guess what, by common consent this is regarded as the optimum level of sharpness. However it's possible to go much finer, either with Shapton stones, other brands of water stones, or diamond pastes. But our eyes can't readily perceive any enhancement after about 8,000 so very few people bother sharpening beyond this. 

It strikes me as an altogether improbable co-incidence that optimum sharpness just happens to be the point where our eyes first begin to perceive a polished surface! 

The wood couldn't care less about polish, neither does the tool, it either cuts cleanly or it doesn't. But the magpie in us is attracted to, and satisfied by, a shiny edge. So we've generally settled on 8,000 grit when for all I know 4,000 grit or 15,000 grit may actually make better empirical sense. 

This is the point I'm trying to make, I suspect 8,000 grit is significant more for the psychological reason that it's the "moment of first polish", than for any scientific rationale.


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## Kalimna (28 Aug 2013)

Custard - I am interested to know your thoughts on th 15/30k shapton stones. Do you perceive a finer edge (in use) when sharpened to the higher grits? The finest I have is a 12k King stone (I think it is King, may not be), and I think that is where funds stop. I am not sure I could persuade the inner magpie to go for the 30k stone, however much of an improvement it is.

Cheers,
Adam


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## custard (28 Aug 2013)

Kalimna":27x0jswe said:


> Custard - I am interested to know your thoughts on th 15/30k shapton stones. Do you perceive a finer edge (in use) when sharpened to the higher grits?



Hello Kalimna, as far as plane blades are concerned no is the simple answer, neither in quality of the cut nor in longevity of the edge! But I'm not sure I actually perceive much of an improvement beyond 4000 grit, which is below the "polish threshold". 

Here's the thing though; a well executed, needle point, half lap dovetail is just, but only just, within my abilities. On a good day I'm happy with them, on a bad day they look terrible. So like a fisherman venturing beyond the sight of land in the days of sail, I'm easy prey for superstitious nonsense! Consequently before attempting an important drawer I'll sharpen my chisels all the way to 30,000 grit, in earlier times I might have thrown salt over my shoulder or checked for black cats in the workshop!


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## woodbrains (29 Aug 2013)

Jacob":2imcdb1c said:


> custard":2imcdb1c said:
> 
> 
> > ....."shiny equals sharp" i.....
> ...



Hello,

Of course you could put oil on a fine waterstone and ruin it. But in the realms of stones meant for sharpening with oil, they are generally not as fine as those meant for water.

Abrading metal with brasso is still sharpening, but you have to get to the point where the brasso will remove the scratches left by the previous grit. Brass is not sharpened in the strict sense in that it is not a hardened edge tool, but brasso will not polish it, either, until the brass was abraded with a sufficiently fine abrasive before hand. There is no difference between sharp or polished, but a semantic one. If an edge tool is abraded with a finer grit it will be sharper and have a higher polish. Whether the grit is fine beyond the point of making a reasonable difference to tool performance does not dictate as to where sharpening stops and polishing takes over; they are one and the same. We have to decide ourselves the practical limits when we work. 

This nonsense about reducing friction has already been de bunked by the carvers who tell us they strop to acheive the ultimate sharp edge. A very sharp tool will have the least friction anyway. A roughly honed tool that is stropped wil still be a roughly honed tool, and cut the wood no better, it will just have slightly shinier but similarly rough scratches. it would be better to go to a finer stone and miss out the strop, if the number of sharpening stages were a consideration. Stropping a tool that has not been sufficiently finely honed is a waste of time. Stropping a dull tool is a waste of time. This was all said only a few days ago, but memories are very short, apparently.

Mike.


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## Kalimna (29 Aug 2013)

Thanks for the reply - I think it answered my question  
Regarding the 'hone to 30k prior to important job' remark - I wonder if psychology realy does play an important role here. If you happen to find sharpening slightly therapeutic anyway, perhaps the action of the extra steps puts your mind in a more relaxed place, and therefore one that is les likely to slip up when concentrating?
Not sure I want to start a 'state of mind as a method of improving sharpness' discussion tho........

Cheers,
Adam


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## Jacob (29 Aug 2013)

woodbrains":3kqg2d0i said:


> ......Whether the grit is fine beyond the point of making a reasonable difference to tool performance does not dictate as to where sharpening stops and polishing takes over; they are one and the same. ..........


No they aren't. Sharpening is what you apply to the edge, stropping applies to an area of bevel and the face extending beyond the edge, though obviously it will "sharpen" in the process.
Stropping/polishing is very effective in improving performance. On a plane frinstance applied to the face and front edge of the cap iron, on a spoon gouge applied to the bevel - which comes into very close contact with the surface of the work. The difference can be very noticeable. Yes you no doubt get the same effect with ever finer stones but it's much easier with a strop.
It's not dissimilar from the candle wax on a plane sole effect - dramatic improvement in apparent sharpness without even touching the edge.


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