You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Mortise Chisels
- Thread starter dwsantos
- Start date
John Walkowiak
Member
Dan,
Mine have a gentle arc goint to the tip, which I hone at about 35 degrees. Some have a flat bevel an inch or so long, then the honing angle of about 35 degrees. You don't have to fret about using a jig to get the angle, just free hand it. Have fun with them, they are an amazing tool.
John
Mine have a gentle arc goint to the tip, which I hone at about 35 degrees. Some have a flat bevel an inch or so long, then the honing angle of about 35 degrees. You don't have to fret about using a jig to get the angle, just free hand it. Have fun with them, they are an amazing tool.
John
Derek Cohen
Member
Hi Dan
Primary bevel at 20 degrees and secondary bevel at 35 degrees.
<img src="http://i13.photobucket.com/albums/a262/Derek50/Chisels/Morticex2.jpg">
Regards from Perth
Derek
Primary bevel at 20 degrees and secondary bevel at 35 degrees.
<img src="http://i13.photobucket.com/albums/a262/Derek50/Chisels/Morticex2.jpg">
Regards from Perth
Derek
Hi Dan,
Ultimately, the angle at which you grind your older mortise chisels will probably be best determined by the hardness of the woods you will typically be using them in. However, as a starting point, I don't think you can go too far wrong by following Peter Nicholson's lead in his 1831 _The Mechanic's Companion_:
" ... The cavity is called a mortise ... and the chisel used for cutting out the cavity is therefore called a mortise chisel. As the thickness of this chisel from the face to the back is great, in order to withstand the percussive force of the mallet; and as the angle which the basil makes with the face is about twenty-five degrees, the slant dimension of the basil is very great. ... "
As far as I can determine, this is the only chisel type for which Nicholson gives a numerical value for the primary angle of the bevel. As to firmer and paring chisels, all he really says is the the paring chisel is "sharpened to a very fine edge" - meaning, I believe, to a more acute angle than the firmer chisel.
And speaking of sharpening, while Nicholson doesn't discuss this specifically regarding chisels, he does discuss it with regard to plane irons, and it seems safe to infer that he intends this to relate to chisels as well. In any event, he discusses grinding the basic bevel on a grindstone, resulting in a hollow grind congruent with the size of the wheel. The honing is then carried out, first on a rub-stone (coarse grit), then on a turkey stone (finer grit), by slightly tipping up the plane-iron/chisel. This results in a small secondary bevel, but Nicholson makes it clear that the primary purpose of this secondary bevel is to minimize the amount of material needing to be honed to arrive at a sharp edge. Indeed, he clearly indicates that the primary should be reground when the secondary bevel becomes large enough to make sharpening cumbersome. In fact, this honing bevel is so small that it doesn't even show up in his accompanying illustration of the mortise chisel.
So, following Nicholson, I would think that a primary bevel of about 25 degrees would work just fine, with a honing angle of about 30 degrees. And my own experience bears this out. I would only increase the honing angle if the edges don't hold up in the woods you are working with.
Don McConnell
Eureka Springs, AR
Ultimately, the angle at which you grind your older mortise chisels will probably be best determined by the hardness of the woods you will typically be using them in. However, as a starting point, I don't think you can go too far wrong by following Peter Nicholson's lead in his 1831 _The Mechanic's Companion_:
" ... The cavity is called a mortise ... and the chisel used for cutting out the cavity is therefore called a mortise chisel. As the thickness of this chisel from the face to the back is great, in order to withstand the percussive force of the mallet; and as the angle which the basil makes with the face is about twenty-five degrees, the slant dimension of the basil is very great. ... "
As far as I can determine, this is the only chisel type for which Nicholson gives a numerical value for the primary angle of the bevel. As to firmer and paring chisels, all he really says is the the paring chisel is "sharpened to a very fine edge" - meaning, I believe, to a more acute angle than the firmer chisel.
And speaking of sharpening, while Nicholson doesn't discuss this specifically regarding chisels, he does discuss it with regard to plane irons, and it seems safe to infer that he intends this to relate to chisels as well. In any event, he discusses grinding the basic bevel on a grindstone, resulting in a hollow grind congruent with the size of the wheel. The honing is then carried out, first on a rub-stone (coarse grit), then on a turkey stone (finer grit), by slightly tipping up the plane-iron/chisel. This results in a small secondary bevel, but Nicholson makes it clear that the primary purpose of this secondary bevel is to minimize the amount of material needing to be honed to arrive at a sharp edge. Indeed, he clearly indicates that the primary should be reground when the secondary bevel becomes large enough to make sharpening cumbersome. In fact, this honing bevel is so small that it doesn't even show up in his accompanying illustration of the mortise chisel.
So, following Nicholson, I would think that a primary bevel of about 25 degrees would work just fine, with a honing angle of about 30 degrees. And my own experience bears this out. I would only increase the honing angle if the edges don't hold up in the woods you are working with.
Don McConnell
Eureka Springs, AR
Share: