Chisel sharpening

[Jacob]

....
Secondly, and perhaps most importantly, Wend specifically said "an old 1/2" chisel" and we can clearly see both corners are dinged or worn. So any supposed golden rule for prep time for new chisels isn't relevant anyway!

May be old but isn't worn out - it still shows that slight convexity you get with new chisels (in my experience). Needs grinding and sharpening yes, but doesn't appear to need any attention to the face. Well it didn't but it does now! :lol:

 

[nabs]

I do think it depends entirely on the state of the chisel/iron in the first place. Of course if you have a new one and it is already flat (or hollow) you don't need to do anything, and minor deviations in flatness can be ignored if you are stropping as leather has enough give in it to compensate.

But if you have a used one and the front part of the face is not flat - e.g it has one or more dubbed corners (as appears to be the case with this one) - then I think it makes for easier sharpening in the long run to flatten it first.

Based on my old chisels this kind of issue is not unusual (no doubt because they have gradually taken on the shape of whatever stone they were sharpened on) and is not difficult to fix.

Wend it is easy to put right - don't be deterred!

 

[D_W]

If you can't get to the wire edge on the back of the chisel, you have a problem. some old ones are in such bad shape that you can get to it on part of the edge, but the rest is relieved. You're left working that wire edge off with compound or something in order to get rid of it (leaving it on and calling it good enough is a "fail" effort unless you're working on rustic pine barn doors and butchering them on purpose).

I can't tell from the OP's first picture if he could get to the wire edge, but if he could, I'd have started working with that and let time and edge refreshing work the back to its final flatness.

Unlike Jacob, I flatten everything first to make sure I can get to the wire edge. I don't spend gobs of time working up to a bright polish then, the first bit of use will leave scratches up the back side of the chisel (cosmetic in nature) and are you going to then waste your time every time you sharpen trying to get superficial stuff like that out? I hope not. You can if you use a medium stone like a washita, it'll take those right out, but if you use a slow 1 micron synthetic stone, you're peeing into the breeze.

Once I get basic flatness, I stop preparing a chisel, though - it'll take a few sharpening cycles to polish the back, but it's a whole lot more fun doing that than it is rubbing chisels on abrasive for an hour.
https://www.youtube.com/watch?v=Z7iYFusg0Tc&t=953s

At the point where a washita can reach the wire edge, the surface planed will be bright even if it's not perfectly clear of any plane marks at all (that only matters if you finish plane). The chisels above easily shave arm hair - anything does if the wire edge has been completely removed - even an india stone will do that, but the earlier you stop, the more you have to do to remove the wire edge.

A run of PSA sandpaper roll stuck to glass is by far the best way to conquer anything that's not ready to go right off of a medium stone. The same about effort is true - get it basically flat so that you can get to the wire edge, and then you will gradually polish the back over time just in use, but you can get functionally sharp right away without doing more than a minute or two of work to knock the smartness out of the coarsely sanded edge that a long lap leaves.

FWIW, I prepared a set of 10 neglected japanese chisels two weeks ago in about half an hour, and that included a significant amount of CBN grinding and some very heavy back removal to take the belly out of the chisels. I'd have never gotten them done if i'd have used stones instead to do all of the back side work. A belt sander is out of the question (something always gets rounded because the belt can't stay completely tight).

 

[Wend]

Thanks everyone for the input.

I'm not interested in making it shiny purely for the sake of it being shiny, so if I shouldn't expect that then I'll stop worrying about it. My aim is to get it to be sharp, and as my previous attempt didn't get it to the point where it will cut paper cleanly (as I've seen in videos on youtube) I've been trying to improve my technique.

I'll see if I can sort that corner out, then try working on the bevel side again, and see if I have better luck this time.

Thanks all!

 

[Jacob]

...
But if you have a used one and the front part of the face is not flat - e.g it has one or more dubbed corners (as appears to be the case with this one) - then I think it makes for easier sharpening in the long run to flatten it first. It has dubbed corners but looks perfectly flat to me (in the first photo, but not after the attempt at flattening!).

The trad way of getting rid of nicks, dubbed corners etc is to grind the bevel, not too grind the face. It's quicker, easier, removes less metal.
I doubt anybody ever bothered to flatten faces i the old days - the didn't have the means easily to hand, hence many used old chisels tend to slightly convex (or "bellied" as it has come to be known latterly. :lol: )

Wend it is easy to put right - don't be deterred!

But don't do it again! If you'd left it alone it would have been fine.

 

[Jacob]

....

Once I get basic flatness, I stop preparing a chisel, though - .......

I've never prepared a chisel. Sharpened a few though.
PS If I bought a chisel which need preparing I'd send it back and ask for a finished one.

 

[D_W]

Thanks everyone for the input.

I'm not interested in making it shiny purely for the sake of it being shiny, so if I shouldn't expect that then I'll stop worrying about it. My aim is to get it to be sharp, and as my previous attempt didn't get it to the point where it will cut paper cleanly (as I've seen in videos on youtube) I've been trying to improve my technique.

I'll see if I can sort that corner out, then try working on the bevel side again, and see if I have better luck this time.

Thanks all!

It's hard to cut paper with a chisel - at least it's a pain and it requires you to have paper around. Just see if you can take a waxy-finish shaving off of a piece of reasonable quality wood. No need for the marshammlowiest pine or anything, just any piece of decent walnut or oak endgrain. If you can do that, it's sharp enough. If you can't get the chisel into the wood or the cut is rough, then there's a bit further that you'll need to go.

 

[Phil Pascoe]

Modern plane irons are always dead flat already.

:shock:

 

[nabs]

The trad way of getting rid of nicks, dubbed corners etc is to grind the bevel, not too grind the face. It's quicker, easier, removes less metal.
I doubt anybody ever bothered to flatten faces i the old days - the didn't have the means easily to hand, hence many used old chisels tend to slightly convex (or "bellied" as it has come to be known latterly. :lol: )

that is a good tip for nicks (if you have a grinder - can you do it on a stone?). Either way I wouldn't want to do it on a big out-of-flat corner like the above - in these cases flattening the back on a stone etc is a simple and reliable way of getting to a point where you can easily remove the bur.

Re. cause and effect - I have to confess that my early attempts at using sandpaper for this type of thing occasionally resulted in me dubbing the odd corner and making things worse (the paper rides up if you aren't careful) but I'm not sure how you'd manage to do the same on a flat and unbending diamond stone!

My theory about the oldie tools is that the problems occur when you inherit a chisel etc that was honed on a stone that is differently flat than the one you have (or was 'improved' by errant sandpaper users!). No doubt if you persevere with normal sharpening it will sort itself out, but I think you will have many unsatisfactory sharpenings in the meantime as it will be hard to remove the burr.

 

[Jacob]

....- in these cases flattening the back on a stone etc is a simple and reliable way of getting to a point where you can easily remove the burr. ....

So why is the OP (and a few dozen similar in earlier threads) finding it a problem? More often than not they are ruining perfectly OK chisels. Somebody a bit back started "flattening" a brand new set of blue spruce chisels. Or is it called "prepping"? Either way he made a pigs ear of them.
It's not simple, it's not reliable, it's easier to do it the trad way, it's not necessary.

...you will have many unsatisfactory sharpenings in the meantime as it will be hard to remove the burr...

If the burr is hard to remove you either grind the bevel a bit more, or lift the chisel a bit to make a less than flat bevel on the face. This is against the tooly rules I know, but if you are just doing woodwork it doesn't matter at all, and that's how a lot of older chisels can be seen to have been done.

 

[nabs]

you have made several points Jacob, not all of which are wrong

1. not all chisels need work on the other side to the bevel - No disagreement from me on this point ( or in this thread I think). As was said above, a good way to find out is to simply sharpen the bevel and see if you can easily remove the burr by rubbing the other side on your sharpening stone/strop. If you can then there is nothing to do.
2. some people are doing it unnecessarily due to the amount of publicity 'flattening' received on t'internet and in the press - yes I expect that is true too.
3. If you have bought a used chisel that is wonky to the extent you can't remove the whole burr, you have to do something to correct it. This can include lifting the chisel slightly, grinding away to the good bit. Agreed also.

The only thing I'd add - and where I think we are disagreeing - is that problems with old chisels (convex backs so the corners don't touch the stone, pitting near the edge, for example) can be easily resolved by flattening the last inch or so of the face, and sometimes they are so bad it is the the best thing to do. I happen to think it is easy to do (but boring), but just in case I have been lucky till now, will read the 'blue spruce' thread (18 pages!) to find out more.

The last point is whether flattening was needed in the OPs case - the only way to really find out what work - if any - is needed on the back of an old chisel is to have a good look at the tool, which unfortunately we can't do in this case as the original photo is too blurry!

 

[knockknock]

The trad way of getting rid of nicks, dubbed corners etc is to grind the bevel, not too grind the face. It's quicker, easier, removes less metal...

that is a good tip for nicks (if you have a grinder - can you do it on a stone?)...

It can be done on a stone, as well as cambering a plane blade. I use an 80 grit stone along with a sharpening jig (which I don't use for normal sharpening). But I would recommend getting a grinder. I live in an apartment, so I prefer not to sling metal and stone dust all over the place.

 

[ED65]

My aim is to get it to be sharp, and as my previous attempt didn't get it to the point where it will cut paper cleanly (as I've seen in videos on youtube) I've been trying to improve my technique.

Paper cutting is a poor test of woodworking edge performance. Papers vary a surprising amount in how cleanly they cut and some have grain so they cut more easily in one direction than another, so some 'catch' a lot and others (cheap ones) part much more readily. Plus, we need push-cutting performance from a chisel edge, not draw-through performance which is what will most readily slice paper.

So there are better ways to test sharpness on woodworking tools.

For plane irons whether the edge will easily and painless shave arm hair isn't the worst test, but it's not the best either because arm hair is so highly variable one person's good results won't match another's. Eventually you'll just get to know what'll get the job done. And irons don't have to be as sharp as you need chisels to be so it's easier to get there.

For chisels the simplest thing it just to go straight to wood and see how it pares as already mentioned. Eventually as you progress, or if you're aiming high now, you will want to test against pine/spruce end grain, but this is an acid test of sharpness and an edge has to be really very good indeed to perform well. Many many chisels that won't pass this test will work perfectly well most common hardwoods including oak and beech.

I'll see if I can sort that corner out, then try working on the bevel side again, and see if I have better luck this time.

Not sure how much metal has been removed since the first pics you posted but if both corners are still missing you need to remove some material from the edge, which will naturally reduce the size of the low spot on the flat if that's still an issue.

This might sound scary but the best way to get that edge straight right the way across is to abrade the edge back flat. If you don't have a grinder this means holding the chisel vertically and stroking back and forth over it. Yes this will create a little flat on the edge that has to be honed away but it's usually much easier to go from there back to a bevel than it is to wear away a bevel until corner damage is gone.

 

[Phil Pascoe]

And it helps avoid burning the edge if you are using a grinder.

 

[Tasky]

For plane irons whether the edge will easily and painless shave arm hair isn't the worst test, but it's not the best either because arm hair is so highly variable one person's good results won't match another's.

I'd have thought so more because you'll rapidly run out of arm (and other body parts) to test-shave, and I'm told the regrowth itches like a son-of-a-beech!!

 

[D_W]

It comes back quite quickly. More dangerous is narrow chisels with corners that make you look like you've been wrestling with cats.

The hair test is quite a good one if you know what to do with it. A sharp edge that has the entire foil removed will shave hair regardless of which way it's oriented on the skin (bevel up, or bevel down). I think most beginners probably don't achieve that, but it's probably easier to sharpen that well than it is to do a "half job". It involves biasing the final step so that you polish only the edge.

Wood is highly variable, too. Even the direction that you're working a piece of end grain.

Another good functional test is to use smooth leather for stropping, oiled leather that is otherwise clean, and if the edge has an unfinished area, it will scuff the leather. If the path behind the iron or chisel is smooth and dark and only scuffed at the corners where they dig in, then the edge is either finished or completely incomplete but smooth. A little experience will eliminate the former. that is my favorite check, it requires no arm hair and no screwing around to find paper or test wood. plus, the bare strop with decent quality clean leather improves every edge no matter what the medium is. There is even improvement if the edge is done on graded chromium oxide pigment, ( which itself is absurd for woodworking in the first place. )

 

[custard]

My aim is to get it to be sharp, and as my previous attempt didn't get it to the point where it will cut paper cleanly (as I've seen in videos on youtube)

If you're taking up origami then maybe this is relevant, if you want to make furniture then it's not. If you ever find yourself in a proper cabinet making workshop, then please don't perform any silly "test the edge" paper cutting routines, otherwise you'll find your fellow craftsmen making up and down gestures with a semi-closed fist. Trust me on this one, furniture makers today will happily tolerate honing guides and branded aprons, but paper slashing is proof of buffoonery!

The place you need to get to is where you simply sharpen your tool and then get back to work, without any "testing" of the finished result. If you sharpen correctly you'll automatically produce an adequate result for even the highest levels of woodworking. If there's any testing to be done it's during the sharpening process, not afterwards. Have you produced a detectable burr along the full length of the edge? When you hone have you produced a polished band along the full length of the edge? If the answer to those questions is "yes" then you're good to go, if the answer's "no" then do it again. It's pretty much that simple.

Good luck!

 

[custard]

Do you need the back of the chisel to be perfectly flat?

Well, it'll help if at least a couple of your chisels are in that shape. The reason is that you'll often reference from the back of a chisel, and that's true even in simple DIY jobs. Take for example if you've used some iron-on edging on a piece of laminated chip board, or if you've got a protruding dowel or peg that you want to cut down flush. Neither of these tasks are exactly Guild Mark level cabinetry, but you'll perform them both better with a flat backed chisel.

Beyond that it depends what your ambitions are. For basic pieces of country furniture you'd be surprised what you can get away with, the truth is you don't need exquisitely finished tools to make quite a lot of furniture. But it's also true that you'll certainly need quality tools fettled to a very high degree if you want to reliably execute precision joinery like this,

It's just a matter of horses for courses. The best thing is to get stuck in making stuff and learn along the way what tools are adequate, and what tools need some more work.

 

[Jacob]

Do you need the back of the chisel to be perfectly flat?

Well, it'll help if at least a couple of your chisels are in that shape. The reason is that you'll often reference from the back of a chisel, and that's true even in simple DIY jobs. Take for example if you've used some iron-on edging on a piece of laminated chip board, or if you've got a protruding dowel or peg that you want to cut down flush. Neither of these tasks are exactly Guild Mark level cabinetry, but you'll perform them both better with a flat backed chisel....

It'd have to be a very strange chisel for the shape to cause a problem trimming a dowel, and no 'normal' chisel (like the OP's) would need specially flattening!
Severely concave could be a prob but you could probably get away with it the other way up, even with a rounded bevel. Anything from flat to convex would be fine, as long as sharp.

 

[Phil Pascoe]

So why are Japanese chisels deliberately very concave?