Mortise Chisel Sharpening

[stubtoe]

Hi,

Without re-opening (I've seen the previous posts!) the can of worms that is 'sharpening', do you sharpen/hone mortise chisels using the same method you would for bevel edged chisels i.e. at 25deg then 30deg for the micro bevel?

Cheers,

Jonny

P.S. If you're interested, I'm going down the hand sharpening/honing route for no other reason than I can't justify spending any more £££s on tools/jigs/rigs as I just want to get started on some projects so will mainly be buying wood!! (hammer)

 

[bugbear]

do you sharpen/hone mortise chisels using the same method you would for bevel edged chisels i.e. at 25deg then 30deg for the micro bevel?

Because of the vigorous work they do, you'll want steeper angles to make stronger edges. Try 30 primary, 35 secondary, and if the edge STILL fails, raise it some more.

The exact preferred angle will depend on the size of your hammer, the quality of the steel, and the hardness of your wood.

BugBear

 

[Racers]

Hi, Jonny

Buying wood!!! get looking in skips and local firms for off cuts etc.

Pete

 

[dunbarhamlin]

For a proper mortice chisel (oval bolstered "pigsticker" or other of similar blade thickness) the primary bezel is not just for your honing convenience, but improves penetration. Consequently, you want a shallow primary bevel (20° is more than obtuse enough) with a high secondary bevel (35° or more.)

Note that the secondary is not a microbezel - it needs to be substantial enough that the tip is sufficiently supported if levering (bearing in mind the acute primary)

I also soften the knee of the primary bevel by using a Grimsdale dip. This makes me less liable to damage the end of the socket when cleaning up the bottom.
For the same reason, I'd avoid chisels with rounded backs (the back is the side with the bezels - not the flat face)

 

[Evergreen]

If you have any traditional, oval bolstered mortise chisels, examine them closely because they may have laminated steel blades. If you find one of these, they're easier to sharpen because the back is quite soft and you can form the primary bevel with a file.

 

[LuptonM]

So does that make Japanese chisels easier to grind?

 

[stubtoe]

Hi, Jonny

Buying wood!!! get looking in skips and local firms for off cuts etc.

Pete

I did just that yesterday and came away with a fair few pieces!

If you have any traditional, oval bolstered mortise chisels, examine them closely because they may have laminated steel blades. If you find one of these, they're easier to sharpen because the back is quite soft and you can form the primary bevel with a file.

Not sure exactly what type they are. Picked them up from a car boot and they need a good clean up and a fair few new handles. Will try to post some pics once they're tidied up.

Thanks all.

 

[Jacob]

Mortice chisels are traditionally sharpened with a pronounced rounded bevel, which starts with a 30º edge (or steeper for strength; depends what you are doing).
There is a very good reason for this. It means you can get the edge into the corner of a blind mortice with the back (bevel side) towards the side of the hole, and then lever away from the corner to scrape it clean. The fulcrum (on the bevel) effectively moves up the bevel and the side of the hole as you lever away, which gives powerful leverage as you start, and avoids levering on the top/outside edge of the hole and deforming it.
The powerful starting leverage is the principle behind curved lock mortice chisels, claw hammers, prise bars etc.
A second very good reason is that it is easier to hone and maintain a rounded bevel, rather than following the modern fashion of prescribed specific angles. In fact you can do all your chisels and plane blades this way, if you wish, but it's deeply unfashionable. Don't let that put you off!

If you only do through mortices then the shape of the bevel isn't going to make much difference as long as the edge is good at 30º ish. Except, obviously, hollow ground would be bad. Rounded would still be easiest.

 

[Karl]

Hi Stubtoe - where are you in Winsford? I'm just off Rookery Rise.

 

[stubtoe]

Jacob - cheers for the detailed explanation. Is the rounded bevel you talk about the same as the grimsdale method I've come across when reading about sharpening?

Karl - I'm on Radcliffe Road (next to Woody Lodge school).

Sent from my Nexus S using Tapatalk

 

[Jacob]

Jacob - cheers for the detailed explanation. Is the rounded bevel you talk about the same as the grimsdale method I've come across when reading about sharpening?...

Yep. Grimsdale; c'est moi!
It's through contemplating a mortice chisel that I hit on the Grimsdale method. It's not really a "method" is just how everybody used to do it before crazy sharpening kicked in. It's how you'd do it naturally if there was nobody about to ask and you hadn't bought the video, the book, the course, the kit, the emery paper etc.

 

[Evergreen]

So does that make Japanese chisels easier to grind?

'Fraid I can't tell you because I don't have any Japanese chisels. But I do have a traditional oval bolstered mortise chisel with a laminated steel blade which only became apparent after I'd cleaned off the Crud of Ages Past. I tested a new file on the chisel back and found it was soft. Forming a bevel was then easy.