Fair Woodworking

February 29, 2012

Skew and Fishtail chisel modification

Filed under: chisel,Fair Woodworking & Hand Tool Blog,Hand tool,Picture issues,Sharpening — fairwoodworking @ 3:32 pm

EDITORS NOTE *** This post is experiencing 3rd party photo hosting “issues”, that will be addressed as time allows. ***

 

Last fall Lee Valley had an in store sale of some discontinued items and old stock.

One of the things they had for sale were French made MOB chisels for $4 each.

I bought 3 of them.

I’ve wanted to make some skew chisels or a fishtail for a while. Now was my chance to make both.

The first thing I had to do is get that pesky lacquer off the chisels.

And what’s a blog post without a little back lapping?

Some quick layout lines with a sharpie and we are ready to go.

The method of grinding here is the same you would use to grind out a chip in a blade. Many people seem to over think grinding, and in the process run into all kinds of trouble.  The benefit of grinders is that they can remove excess material quickly. The danger is that they can over heat your blade causing it to loose its temper.

On a side note, I was talking to some friends the other day that were discussing if quenching hot blades in water could damage them. In my opinion, if you are allowing them to get that hot, you probably are already doing something wrong. The most likely would be using your factory supplied grinding stone. All you need for grinding is a cheap bench grinder, but the supplied stone is really truly worthless and generate a ton of heat. I replaced my with a Norton Cool Grinding Wheel I understand the Blue Norton 3X are great as well. I also use a Wheel Dresser when I notice the stone is not cutting as quickly.

When doing heavy grinding like this or for chip removal. I don’t grind with the bevel. That would guarantee burning. Here I grind with the blade square to the stone so there is maximum metal behind the ground surface to work as a heat sink. Through this whole process the blade didn’t get past barely warm enough to notice.

This is totally free hand. My finger is between the blade and the tool rest, and I eye-ball as I grind square to the line I marked. You have to remember that this is just grinding. It’s not a precise action. Too many people get all worked up about how they don’t have the skill to do this. Relax, just don’t burn the blade!

With both the skews ground, it’s time to work the bevel.

You can see how one side is blunted wider? That’s the part to go after.

When done, it will look like this, but I better camp here for a bit. It looks like I’ve ground right to the cutting edge. This is important…. I didn’t. I ground until I was very close to the cutting edge. About the thickness of a pen line. Any closer and there is a good chance I’d burn the edge. This chisel is now ready to finish lapping and sharpening.

Ok, I’ve finished grinding both skews. The one shown on the bottom looks a bit funny because not all the old bevel had to be ground off.

Next I did the fish tail. I left this one to last because I thought it would be the most difficult. Let me put your mind to rest. It’s a no brainer.

Just grind to the line.

That’s it!

It’s so basic, I didn’t even bother taking a picture of it. Well, that isn’t really true. I forgot to take a picture of it…

Grinding to the first line is easy. The second line takes a little more care. You see the first line is ground with the chisel handle pointing away from the grinder. The second one would need you to point it into the center, and you can’t get the right angle with the grinder motor in the way.

Solution? Grind with the back facing down.

To do this you will need to mark the angle on the bevel side of the blade, but that’s no big deal. As you grind, stop to take a look at the line on the back to see when you want to stop.

Party on, dude!

 

If you are interested, I took all three chisels out for a test drive. You can read about it HERE.

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