Laziness and learning...

bolster welding

Bill Tindall, E.Tn.

Of no importance to me. It just needs to wedge in its stopping place. If it works up the tang during handle installation it is a trivial task to bash it back into its place with a deep socket wrench.

Re: Laziness and learning...

John in NM

"(nobody yet has said "could you make a socket chisel like LN? - it's only a matter of time)"

Heheh - I know where you can use a drop hammer Jump right past LN!

Unfortunately its on this side of the country....

Bowing and pounding

Bill Tindall, E.Tn.

For a multi tasker chisel I what it straight. If the small width chisels I use were long and bowed they would flex when struck. When we made chisels the heat treatment company asked what the material was being used for. They replied that they would "straighten" the pieces after heat treat. Indeed they came back straight.

chisels and chainsaw bars...

David Weaver

..I think the default is probably straight now whereas older chisels sometimes have the positive bow that I added (less drastic) as a bias.

Why the bias is there, I don't know, but I'd speculate it may be for control, or it may be for ease in honing (usually results in the last inch or two of the back of a chisel being in contact with a coarse abrasive and maybe a little bit less with the stone.

I make the narrow chisels flat for the reason you mention - they need to go in a straight line (at least I feel like they do) unless they're going to be a tall cross section chisel. I've got a vintage socket mortise chisel that's about 1/10th inch wide and probably more than 1/4th inch tall, and it has the same gradual bow over its length.

None are as bowed as the brown handled chisel that I sent you, though - I've only seen that now that I think about it, on japanese chisels (a radius similar to that).

The other thing (Just looked at three socket chisels that are long and probably intended for framing type work), some of the chisels have a mild bow in the last 3 inches or so and then after about 5 inches, the rest of the chisel isn't that careful (in two, the grind is actually hollow after that and if you put the entire chisel back on a surface, the edge wouldn't touch the surface - The hollow part is noticeable (think a mild S for the whole thing, but mild meaning like a 32nd of an inch each way or less). I think they're intended to have some relief , but the maker never intends the top part of the chisels to actually be deep in a cut - which leads to a question as to why they're so long then - but that's for another day.

Most of my chisels are flat, though.

All of the heat treat services that I've seen offer to flatten items - even if the item is unusual like a chainsaw bar, it'll be either hammered flat or flattened in some kind of high pressure machine that flattens and reduces local tension in the metal (I have no idea how those machines work).

I'd guess that most modern users are uninterested in subtle biases - I doubt any chisels other than some japanese chisels are made with the convex length across the back.

(I can level the backs of the chisels on a flat belt platen and they'll be almost dead flat after heat treat - and any remaining out of flatness can be corrected with a few hammer strikes on an anvil after temper). It's possible that I'm the only person who sends tools into diving cuts and has that canceled out by the gradual bow at the end - it's certainly not compatible for people who use paring blocks fixtured ahead of their work.

Cannon

David Weaver

I don't have any cannon or expensive japanese bars, but watched cannon's factory video yesterday and I guess I never thought about chainsaw bars, but they fully harden the bars from end to end and then do something with the hardness at the groove to extend life of the bars - they showed a factory worker with a very heavy hand also hammer correcting the bars.

They also had one of the machines that I mentioned in the other post - it looks like a wide belt sander, sort of, and it apparently removes twist and flatness errors from a bar. Why they have both (The hammer guy and the machine), I don't know.

Chisels have an easier life than chainsaw bars, though - I noticed several times that they were concerned about end to end stress relief to prevent any bars from getting cracked in use.