Corner chisel out of square. . .Fixes?

[Matt Evans]

Well, someone handed me a corner chisel. A great gift, particularly since it is a Butcher. But. . .

I went to sharpen it this evening, and realized something. It isn't even remotely square. If this were tool steel I would heat and bend, but I haven't worked with cast steel in such a fashion. I could always grind it square, but I would lose a lot of material, and I would rather not weaken it that much.

So, if you can see the pictures, any suggestions?

[harry strasil]

Check your square to be sure its square.

[harry strasil]

In about 1739 an English watchmaker, Benjamin Huntsman, discovered that under the right conditions blister steel could be melted in a crucible and stirred while liquid. This caused very uniform distribution of the carbon. Steel made this way was called “cast steel.” By the late 18th century "cast steel" was being used for cutlery and chisels. Contrary to popular belief a chisel marked "Cast Steel" was not cast! It was forged from a bar of steel that had been made through the crucible process. (In the early 19th century some rifle barrels were made of cast steel but most were wrought iron until after the Bessemer process made uniform, high-quality steel much cheaper in the mid-19th century.)

[Matt Evans]

Harry, I just refurbished that square. It is as accurate as they come. (ok, maybe not as accurate as a Starrett, but darn close) You were actually one of the first people that popped into my head when thinking about fixing it.

That being said, I couldn't get a picture to turn out, but it looks as though the chisel is square 1 1/2" toward the handle, and the ends "fishtail" out. I can't see shortening the chisel that much, so I am still looking for a fix.

[harry strasil]

Just grind the outsides till its square, the center part is the part that takes the most abuse from use. When I sharpen mine I always give them a little taper from the center out so it has more of a skewing action, makes it cut much easier.

[Matt Evans]

Darn it Harry, if you pique my interest any more I will have to take up a serious study of black smithing! And end up with a forge, crucibles, more tools, and even less time!

That is a bit of history I did not know. Interesting. I had actually thought, likely with every other Tom, Dick, but definitely not Harry, that "Cast Steel" was cast. Makes me wonder what other notions I have that are a bit off base.

It makes sense though, in hindsight. I always did wonder about the possibility of a badly cast chisel snapping under use, and wondered how they got the casting perfect, but couldn't do the same for plane bodies and other castings.

Harry, if you pique my interst any more

[harry strasil]

cast steel was actually wrought that had carbon added to make it blister steel and then remelted before forging it to shape to blend the carbon throughout the material, instead of just having the hardnable carbon on just the outside. You not going to hurt it by heating and reforming, just take it to critical 1460° before quenching and make sure there is no scale on it by wirebrushing before quenching. regrind to desired shape and put in wifey's oven at 375 to 400° for an hour to temper, then requench, it should have a light straw (yellowish) color to it after quenching after tempering.

[harry strasil]

for what its worth, most steels start to form scale, which is actually carbon on the outside at 1550°.
By critical I mean the transformation point. above 1460 the grain enlarges and strength is weakened.

[harry strasil]

You can easily tell the tranformation critical point as a good magnet suspended on a thin wire will not attract the iron at 1460°. that is the old way of telling, its called the nonmagnetic stage. and its very accurate.

[harry strasil]

When we reforged the cutting edges on old Cable Tool drilling rig tools, we did not work it below nonmagnetic or it would crack, peel and break while working.

[harry strasil]

if you have a harbor freight store near you, get a set of their V blocks and use them to work the ends square by laying the hot chisel in the V block and tapping the inside of the V with a piece of any iron that you have formed a 90° V end on.
Don't hit it hard just tap it , move it some and tap again. till its right. I made myself a set of swage blocks to do things like this, the one on the right end, next to it is the base they all fit into.

[harry strasil]

You can actually make yourself a corner chisel out of the modern mild steel, its has a higher carbon content than the old mild steel, because it comes from Mini Mills, where they use electricity to melt scrap iron of every kind in large crucibles and so it has more carbon content.

just forge one end down to a tapered square to make a tang for it, then heat it up and quench it. you will be surprised how hard it is, normally a hacksaw will not cut it. if you want it harder, there is a very caustic method the old timers used, by putting a can of lye into a gallon of water and quenching in that, most modern smiths use a product called super quench, that is not caustic to do this.

[dan sherman]

You can actually make yourself a corner chisel out of the modern mild steel, its has a higher carbon content than the old mild steel, because it comes from Mini Mills, where they use electricity to melt scrap iron of every kind in large crucibles and so it has more carbon content.


Over the last 30 years my dad has worked in various mills, and all of them have use electric arc furnace. I have toured a few of the mills, and the sound a furnace makes is deafening.

[harry strasil]

Over the last 30 years my dad has worked in various mills, and all of them have use electric arc furnace. I have toured a few of the mills, and the sound a furnace makes is deafening.

I toured a mini mill once and the guide told me that the private elect transmission line they had into the mill cost them $750K a month, but would not commment on the 36 inch natural gas line they had to heat the reheat line. and when a piece of alum or brass was encountered by the large electrode in the remelt pot, molten metal was scattered over about a 50 ft radius of the pot.

[george wilson]

After taking a longer look at that chisel,I wouldn't be too surprised if it wasn't a flat one that someone TRIED to convert to a corner chisel. The chisel IS ground with an inside bevel. The way the back side of the chisel looks,it could be a converted chisel someone got a blacksmith to do. It was done pretty competently. The guy just didn't get it square. It really isn't like other old corner chisels I've seen. Too small.

As suggested,grinding it on the outside would fix it IF you can do it accurately. It would best be done on a belt grinder.

Last,IF the chisel is a conversion,I wonder if he re hardened and tempered it correctly?

The chisel isn't very thick. You need to be careful that you don't get it any thinner than necessary. Take equal amounts off each side. the chisel could end up cracking on you in use. Another idea: Grind a bevel on the OUTSIDE,and just use it as a V carving tool.

[dan sherman]

I toured a mini mill once and the guide told me that the private elect transmission line they had into the mill cost them $750K a month, but would not commment on the 36 inch natural gas line they had to heat the reheat line.

My dad worked here (http://en.wikipedia.org/wiki/Northwestern_Steel_and_Wire) right before it closed, and I can remember him telling me the monthly power bill was was in the upper $2 million range. The more interesting part was that they had to give the power company 30mins notice if they planed to bring the furnace on/off line, as to avoid any damage to the local power grid.

[Matt Evans]

Good suggestions. I will take a harder look at it this evening when I get home and see what I can do.

The only problem with using it/converting it to a V-tool is that I already own carving chisels, but have wanted a few corner chisels for some time now.

[george wilson]

I don't know what metal working facilities you have. If I wanted to make the chisel more square,and didn't want to make it any thinner than it already is,I'd get a 90 degree V block,which I think Harry already suggested,and make up a piece of square cold rolled steel to lay inside it. The square piece of steel would have to be ground to a greater than 90 degree angle to fit the inside of the chisel,which has tapered inside sides,plus a few degrees more to make the chisel spread out and fit the V block. I'd heat the chisel good and red,and form it to fit the V block,then restore the heat treating.

As short as the chisel is,though,it won't be as easy to eyeball it to make sure it is at 90 degrees to the mortise you are working on.

[Larry Frank]

Just a minor clairifcation

The scale on the outside of steel or iron is some form of iron oxide. There may be some traces of other elements but it is primarily iron oxide. Any carbon that was near the surface comes of typically as carbon monoxide.

The carbon in the steel produced in a modern electric furnace is not coming from the carbon electrodes. The goal in such an operation is to keep the amount of electrode used per ton of steel to a minimum due to the high cost of the carbon electrodes. Typically, cheap carbon is blown into the furnaces along with oxygen to increase the rate of melting. The total energy for melting the steel and bringing it up to a tapping temperature of around 3000°F is provided by various combinations of natural gas, oxygen and carbon injection and electricity. The amount of each used is somewhat dependent on the type of scrap that is melted and the current costs for natural gas, oxygen, injection carbon and electricity.

Most electric furnace operations will use oxygen to blow the carbon down to under 0.10% and then at tapping of the furnace add the various alloys such as carbon, manganese, silicon and others to hit the required chemistry.

The operation that I worked in produced melts of about 125 liquid tons and melted the scrap and brought it up to temperature in about 75 minutes. The operation was very similar to many other modern electric furnace shops both domestic and foreign. Some shops have the ability to melt similar amounts of steel in less than an hour. As someone mentioned it is very loud and also very hot.