Mortise chisel sharpening considerations

[jppierson]

I have three mortise chisels that need a little TLC.  Is there anything special I need to do or consider besides flattening the back and setting the primary correctly?  UTube only had one (do ya believe it?) video on the subject.  The presenter stated that you should hone the sides also.  He says that the front edges of the mortise chisel is what makes for clean sides so these leading edges need to be sharp also. Seems to me that it would change the width of the chisel over time, and would be akin to sharpening the outside of brace bits.  Does a mortise chisel get a micro bevel?  I would imagine that the ruler trick would be a no go.  What say you all?

[Strokes77]

I have three mortise chisels that need a little TLC.  Is there anything special I need to do or consider besides flattening the back and setting the primary correctly?  UTube only had one (do ya believe it?) video on the subject.  The presenter stated that you should hone the sides also.  He says that the front edges of the mortise chisel is what makes for clean sides so these leading edges need to be sharp also. Seems to me that it would change the width of the chisel over time, and would be akin to sharpening the outside of brace bits.  Does a mortise chisel get a micro bevel?  I would imagine that the ruler trick would be a no go.  What say you all?

No way I would touch the sides.  I set the microbevel at around 35degrees, but I dont think I really measure it on my Ray Iles chisels.  My mortise chisels are D2 steel.  I give a quick flip over and polish on the back to knock burr off... but no way I'm spending the time to flatten that thing back there... I mean, it's flat.. but it's not "flat"...

I may be crazy, but I don't get these as "sharp" as my bench chisels... Even if I do take it to that level of sharpness, I feel it's gone after the first few chops, and then it's back to just regular ol sharp... but, I can cut several mortises with that same edge no problem; so I just hit it and go.  I'll occasionally strop between mortises, but I can't say that makes a difference, just gives me a break from chopping.

[Peter Tremblay]

I have three mortise chisels that need a little TLC.  Is there anything special I need to do or consider besides flattening the back and setting the primary correctly?  UTube only had one (do ya believe it?) video on the subject.  The presenter stated that you should hone the sides also.  He says that the front edges of the mortise chisel is what makes for clean sides so these leading edges need to be sharp also. Seems to me that it would change the width of the chisel over time, and would be akin to sharpening the outside of brace bits.  Does a mortise chisel get a micro bevel?  I would imagine that the ruler trick would be a no go.  What say you all?

I'd say a shallow primary bevel, maybe 15 or 20 degrees

Then a substantial secondary bevel of 35 degrees.  

I'm not sure a flat back is that important.  Just something close enough to chop straight.  It would have to be really wonky not to chop straight.

I wouldn't touch the sides.

[jppierson]

Strokes and Padre,
Thanks! You saved me a boatload of work.

[AHill]

While a mortising chisel is more of a brute force instrument, any edge tool will benefit from being sharp.  I would flatten the back the same way you flatten a bench chisel's back - preferably to 8000 grit.  You only have to do this once.  The recommendations above for bevel angle are good advice.

[Timberwolf]

I have three mortise chisels that need a little TLC.  Is there anything special I need to do or consider besides flattening the back and setting the primary correctly?  UTube only had one (do ya believe it?) video on the subject.  The presenter stated that you should hone the sides also.  He says that the front edges of the mortise chisel is what makes for clean sides so these leading edges need to be sharp also. Seems to me that it would change the width of the chisel over time, and would be akin to sharpening the outside of brace bits.  Does a mortise chisel get a micro bevel?  I would imagine that the ruler trick would be a no go.  What say you all?

............
Here's my take on it...The manufacturer knows { or is supposed to know } the best bevel angle for his edge tools...He wants them as sharp as they can be yet still able to retain that edge after a fairly long period of use.That is the " compromise " .. Too hard it will "chip"..too soft it will dull quickly......The edge "may" not be as sharp as I want it to be { a sharp edge takes less of my energy },  so I lower that basic angle a few degrees and if the edge holds up a sufficient amount of time { to my satisfaction }, I leave it at that angle..If that edge dulls too quickly or chips/rolls, I then have to micro-bevel it a couple of degrees...It's easier { and faster } to restore a micro bevel than the full beveled face of the tool, and I want to spend the time working wood...not sharpening...so IMO a micro-bevel is a trade-off to be used if the original angle wont hold up or has been compromised.

As a world famous British plane maker once said something like....."a good steel doesn't need a micro-bevel..why would you blunt a finely sharpened edge"....
Karl Holtey

[Derek Cohen]

I have three mortise chisels that need a little TLC.  Is there anything special I need to do or consider besides flattening the back and setting the primary correctly?  UTube only had one (do ya believe it?) video on the subject.  The presenter stated that you should hone the sides also.  He says that the front edges of the mortise chisel is what makes for clean sides so these leading edges need to be sharp also. Seems to me that it would change the width of the chisel over time, and would be akin to sharpening the outside of brace bits.  Does a mortise chisel get a micro bevel?  I would imagine that the ruler trick would be a no go.  What say you all?

Here are two chisels, the top a (then) new Ray Iles, and the bottom a good condition vintage Ward ..



If the Ward had been pitted along the sides, as a number of old and dilapidated versions are, I would have (and have done) lightly lapped the  sides until the lands were sharp. The lands will cut the sides of the mortice and keep it clean. This process may remove a small amount of width, but they does not matter - often the chisels are over-wide, and anyway one just cuts the tenon to fit the mortice.

All these chisels have a 20 degree primary bevel and a 35 degree secondary bevel. The secondary is added as a rounded bevel (ala Paul Sellers - the only time I hone a blade like this), since blades are freehanded and not held in a guide. Below is my jig to aid in maintaining the correct bevel angle ..



Close up of bevel ..



Regards from Perth

Derek

[BillMcD]

I agree with the above and would only add a point about the sides.  One of my mortise chisels has parallel sides.  The others are tapered, with the top face rounded over (as seen in Derek's close up of the bevel).  I mention the sides because the sharp corners do help shear off material and cleanup the side walls of the mortise when I am levering the chisels in the mortise.  Having the back face corners sharp and the front rounded and tapered means that shearing only happens in one direction.  On the square chisel, that shearing takes place back and forth.  Those edges can be sharpened adequately without removing anything from the sidewalls beyond the burr.  It's just another thing to consider.  Personally, I prefer the tapered/rounded configuration because I tend to slice my fingers on the sharp/squared front edges.  I chose to intentionally blunt the front corners of the square chisel.  Chop, Chop.

[Strokes77]

This forum is fantastic for learning. Hundreds of years of combined experience, and people willing to share.

[Peter Tremblay]

This forum is fantastic for learning. Hundreds of years of combined experience, and people willing to share.

Friends, family, and aquaintances are amazed when I tell them that I'm a "self taught" woodworker.

But, in truth, I just read and asked questions on this forum for years.

I've also met some of my best friends on this forum.

Good people here!