Chisels sizes, what for what work?

[bridger]

most of the chisels I buy are well used. if I can find 100 year old ones, more the better. some (most) of these need considerable work to get the flat side flat. not being one to spend unnecessary time rubbing chisels against rocks, I have found some fast and effective if unconventional methods of arriving at a working chisel. the usual problem is that the flat has been rendered convex by years of wiping off the wire edge, using the chisel as a scraper on concrete or such, and similar abuse. generally I will start at the bench grinder, shortening the chisel by just enough to remove the worst of the damage at the edge and establish a new rough bevel. then I will address the flat. if it is within range of flattening on a coarse stone, I'll proceed from there. if it needs more than that, I'll use a pneumatic angle grinder with an approximately 2" disk mounted to carefully hollow out a slight concavity in the center of the flat. from there I will take it to the coarse stone. not wanting to over aggressively remove metal from a nice chisel, I generally alternate a few strokes on the stone to show up the high spots with a few strokes with the disc to remove those high spots (avoiding the edges, of course). when the surface produced by the stone reaches the edge, I'm done with the grinder and can move on up through the grits. this often leaves a few hollow ground areas somewhere on the flat of the chisel, just not right at the edge. over time and honings those do diminish and even disappear. I do generally give the whole flat of a chisel a few strokes on the stone each time I sharpen it- it's just part of the routine.

none of this is specifically about prepping new chisels, of course.

 

[Jacob]

most of the chisels I buy are well used. if I can find 100 year old ones, more the better. some (most) of these need considerable work to get the flat side flat. ......

Why do you think they need flattening if most of them have been used (sometimes for 100 years!) in an un-flat condition? Do you think their previous owners all had no idea and only now have we discovered what to do with them? Seems very unlikely to me.
I think you are wasting your time flattening them, shortening their lives (removing a lot of metal) - and disseminating misleading information in the process!

 

[deema]

I'm with Jacob, a good number of my chisels are from my great grandfather, he along with my grandfather and father were all apprenticed cabinet makers. I'm not 'trained' and only profess to know which end is sharp! The chisels have been through, with me, 4 generations and not one of the Chisles has seen any action to flatten them. The work they have produced in the hands of my ancestors is in my humble opinion stunning.

 

[bridger]

most of the chisels I buy are well used. if I can find 100 year old ones, more the better. some (most) of these need considerable work to get the flat side flat. ......

Why do you think they need flattening if most of them have been used (sometimes for 100 years!) in an un-flat condition? Do you think their previous owners all had no idea and only now have we discovered what to do with them? Seems very unlikely to me.
I think you are wasting your time flattening them, shortening their lives (removing a lot of metal) - and disseminating misleading information in the process!

Generally it isnt the effects of use by generations of fine craftspersons that I need to correct for, it's the damage done since the last skilled owner exited and the subsequent bashing about with steel hammers, opening of paint cans, scraping paint off of sidewalks, use as prybars for automotive disassembly, etc....

 

[Benchwayze]

Have a look at the backs of Japanese chisels. They have just a small percentage of the back as flat. As you sharpen them, they are kept flat as time goes on. If you tend to the backs each time you sharpen, then it will take care of itself, as the blade shortens. Same with plane irons. I flatten the face maybe 3/4" back at most, by hanging the blade over the edge of the stone. It's quicker to remove the burr, quicker to flatten, and it moves back with repeat sharpening over time. Never found the need to have a bench chisel or iron face flat all over, nor a mirror finish. A satin surface will give me all the reflection I need for judging angles by reflection, and as long as the face is flat enough to cut decent housings, I am happy. I usually get at those with a hand router afterwards anyhow.

 

[Benchwayze]

Hello,

Obviously the bevel has to be honed as required, but the backs never again, save removing the wire edge on the finest stone, which will look after the backs forever more and not make any significant convexity for the life of the tool.

I think there are many inferences that the back does not need to be polished at all, or so rudimentarily as not to do what we know it needs, i.e. to the same level of fineness as the bevel will receive. Jacob's photo is OK in the respect that the edge that meets the tip is continuously flat. The level of coarseness evident however, means that tool will not be sharp enough, whether the bevel receives the same (coarse) finish or a finer one.

Mike.

If you really must polish, then okay. But the whole face? What do you do next time you hone? Do you always take off the burr, on the heel of your hand? Or do you then spend an hour on successive grades of abrasive, to make sure you don't mar the polish? I agree; the flatter the face, then the smaller the striations at the edge will be; in theory, the sharper will be the edge. But we are talking about minute serrations, which need a microscope to be seen. So my chisels don't have mirror faces. They would still open your hand to the bone, in a microsecond, if you weren't careful. Sharp enough for working wood I think.

 

[bridger]

There is definitely some satisfaction to a well prepared chisel back. Working the whole flat to a mirror polish is a lot farther than I'm willing to take it. If I can get to a decently fine grit for the first 1/8" all along the edge and that in plane with whatever are the high points further back, especially if this plane of high points makes up say at least 50% of the flat face of the chisel I'm happy. From there, normal sharpening practice will maintain the tool in working condition.

 

[bugbear]

There is definitely some satisfaction to a well prepared chisel back. Working the whole flat to a mirror polish is a lot farther than I'm willing to take it. If I can get to a decently fine grit for the first 1/8" all along the edge and that in plane with whatever are the high points further back, especially if this plane of high points makes up say at least 50% of the flat face of the chisel I'm happy. From there, normal sharpening practice will maintain the tool in working condition.

All agreed; and to clear up some confusion "up thread", one simply removes the burr using the finest abrasive, if it hasn't already detached itself.

As Kingshott said (quoting from memory) - once the back is polished (for the first time) it only ever sees your finest stone.

BugBear

 

[Jacob]

.........
As Kingshott said (quoting from memory) - once the back is polished (for the first time) it only ever sees your finest stone.

BugBear

Unless there is wear on the face, which is usual, in which case the flatteners would have to re-flatten. Normally the convexity takes care of a bit of wear (see ref to jap chisel above) until the convexity is gone, when taking off the burr may mean lifting the chisel a bit, resulting in a slightly convex face, which is seen on many well-used old chisels.
Kingshott is waffling!

 

[bugbear]

Normally the convexity takes care of a bit of wear (see ref to jap chisel above) until the convexity is gone, when taking off the burr may mean lifting the chisel a bit, resulting in a slightly convex face

Did you mean concavity (words in red)?

BugBear

 

[Jacob]

Normally the convexity takes care of a bit of wear (see ref to jap chisel above) until the convexity is gone, when taking off the burr may mean lifting the chisel a bit, resulting in a slightly convex face

Did you mean concavity (words in red)?

BugBear

oops yes I meant concavity!

 

[Benchwayze]

BB,

You mention confusion. Personally, I don't have any. I don't see the need for a highly polished, mirror face on a chisel. I want it flat, and reflective enough to read newsprint. (Albeit in mirror fashion!) You don't need a mirror finish to achieve that. Polished surfaces are rarely plane and if that seems contentious, then consider:

In the world of telescope making, achieving a flat surface by polishing is extremely difficult. Some consider it an art, rather than a skill. Flattening glass is somewhat different to flattening carbon steel, but only in the fact that the materials are different. They both respond to polishing in the same way though, and the principle is the same. Another unusual aspect to my sharpening, is the fact that my fine Japanese water stone has ruined more than one cutting edge, by producing 'turned edge'. The very same effect you get when polishing glass.

When I handled Jim Kingshott's chisels, they didn't seem particularly mirror-like to me. They were wicked sharp though, and they were flat on the face! But, Jim worked in an environment where (in long gone times.) it was forbidden to sit down to work, or even wear specs. Therefore, I can't see a shop foreman being pleased with a worker who 'wasted time', polishing the backs of his chisels. I can just assume that after retirement, Jim pleased himself.

If all that makes me sound like our Jacob, then so be it. I won't go on about it any further. 8)


Cheers BB.

John

 

[bugbear]

In the world of telescope making, achieving a flat surface by polishing is extremely difficult. Some consider it an art, rather than a skill.

Even I will freely concede that the surfaces of my sharp edges are up to neither the surface finish nor planar accuracy of telescope mirrors!

BugBear

 

[Benchwayze]

Ohhh I can't 'see' that BB! :lol:

 

[bridger]

taking off the burr may mean lifting the chisel a bit, resulting in a slightly convex face, which is seen on many well-used old chisels.

over time this can result in a significantly rounded chisel. for some operations this is not a problem- it can even be helpful in increased finger clearance and subtle control of depth of cut, but for many other operations it makes the cut unpredictable and complicates sharpening. for vintage chisels that I find my preference is to return the flat side to a non- convex state.