This one:

http://www.amazon.com/Narex-NAR81341.../dp/B0049MXKZM

I will be making through mortises in oak, or possibly some other
hardwood. Some of the stock will be 1.5" thick. I was worried that
squaring the corners of the routed mortises was going to be a
debilitating chore, but I am encouraged by my first couple of tests with
this chisel.

At its "just-from-the-package" sharpness, it makes a nice clean corner.
Any imprecision will thus be attributable to my lack of skill rather
than the tool. I intend to practice up some.

Next, it's not terribly difficult to plow through the oak. OK, I'm only
gouging out a 1/4 x 1/4 corner in a 1/2" mortise, but it sure is easier
with this purpose-built tool. My test runs have been on 3/4" scraps, so
half the thickness I'll need, but it is very quick. My attempts with
standard bevel-edge chisels were much more cumbersome. I think that the
bevel on this chisel may be at a steeper angle, besides the corner
configuration.

Now I need to learn how to keep it sharp. People recommended diamond
hones, but I see at least 5 "colors" (grits). Any tips as to which
one(s) I need?

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Greg Guarino wrote:
This one:

http://www.amazon.com/Narex-NAR81341.../dp/B0049MXKZM

I will be making through mortises in oak, or possibly some other
hardwood. Some of the stock will be 1.5" thick. I was worried that
squaring the corners of the routed mortises was going to be a
debilitating chore, but I am encouraged by my first couple of tests
with this chisel.

At its "just-from-the-package" sharpness, it makes a nice clean
corner. Any imprecision will thus be attributable to my lack of skill
rather than the tool. I intend to practice up some.

Next, it's not terribly difficult to plow through the oak. OK, I'm
only gouging out a 1/4 x 1/4 corner in a 1/2" mortise, but it sure is
easier with this purpose-built tool. My test runs have been on 3/4"
scraps, so half the thickness I'll need, but it is very quick. My
attempts with standard bevel-edge chisels were much more cumbersome.
I think that the bevel on this chisel may be at a steeper angle,
besides the corner configuration.

Now I need to learn how to keep it sharp. People recommended diamond
hones, but I see at least 5 "colors" (grits). Any tips as to which
one(s) I need?

It rather depends on what needs doing, wot? I use silicon carbide but the
same ideas apply...

180/220/280 if I need to take out nicks, 400 & 600 to finish, rarely up to
1000. Don't forget the backs.

I would think silicon carbide on a block would work well for that, sharpen
both edges evenly & simultaneously.

On Saturday, May 16, 2015 at 10:06:16 AM UTC-7, dadiOH wrote:
Greg Guarino wrote:

[about sharpening a corner chisel]

Now I need to learn how to keep it sharp. People recommended diamond
hones...

.. I use silicon carbide but the
same ideas apply...

180/220/280 if I need to take out nicks, 400 & 600 to finish, rarely up to
1000. Don't forget the backs.

I would think silicon carbide on a block would work well for that, sharpen
both edges evenly & simultaneously.

Needs a special block or the geometry is wrong. If the corner chisel is 90 degrees
and the edges are straight across, then the bevels on the inside are NOT
at 90 degrees to each other.

For a 20 degree bevel at the edge, the corner chisel block would have to be
96.77 degrees

For other bevel, the formula is

cos(block_bevel) = sin(chisel_bevel) **2)

and you can't use the 'acos' function, because the branch is wrong...

whit3rd wrote:
On Saturday, May 16, 2015 at 10:06:16 AM UTC-7, dadiOH wrote:
Greg Guarino wrote:
[about sharpening a corner chisel]

Now I need to learn how to keep it sharp. People recommended diamond
hones...
.. I use silicon carbide but the
same ideas apply...

180/220/280 if I need to take out nicks, 400 & 600 to finish, rarely up to
1000. Don't forget the backs.

I would think silicon carbide on a block would work well for that, sharpen
both edges evenly & simultaneously.
Needs a special block or the geometry is wrong. If the corner chisel is 90 degrees
and the edges are straight across, then the bevels on the inside are NOT
at 90 degrees to each other.

For a 20 degree bevel at the edge, the corner chisel block would have to be
96.77 degrees
If the back faces make a 90-degree angle, then so will the ends of the
inside bevels. I'm not sure how the "corner" can cut a perfect corner--I
suspect that,without some deviation from what I have described,that it
can't cut a perfect corner. In this case, I think if the corners of the
tenons could were shaved just the slightest amount, that theywould have
a perfect fit in a mortise cut with this tool. Or perhaps, one could
finish with a regular chisel to create the "perfect corner" if desired.
All of this just a guess--Bill.


For other bevel, the formula is

cos(block_bevel) = sin(chisel_bevel) **2)

and you can't use the 'acos' function, because the branch is wrong...

On 5/17/2015 12:47 AM, Bill wrote:
If the back faces make a 90-degree angle, then so will the ends of the
inside bevels. I'm not sure how the "corner" can cut a perfect corner--I
suspect that,without some deviation from what I have described,that it
can't cut a perfect corner.

At my level of expertise it's unwise to be too certain about things, but
I don't understand why you think that the cut won't match the shape of
the chisel. Do you perhaps mean that the outside corner of the chisel
must actually have some tiny radius to it?

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Greg Guarino wrote:
On 5/17/2015 12:47 AM, Bill wrote:
If the back faces make a 90-degree angle, then so will the ends of the
inside bevels. I'm not sure how the "corner" can cut a perfect corner--I
suspect that,without some deviation from what I have described,that it
can't cut a perfect corner.

At my level of expertise it's unwise to be too certain about things,
but I don't understand why you think that the cut won't match the
shape of the chisel. Do you perhaps mean that the outside corner of
the chisel must actually have some tiny radius to it?

Either that, or there is a slice in the corner. Think about what the
corner must look like if it is at the intersection of 2 bevels. It seems
like to cut a real corner that the bevels would need to be separated.


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"dadiOH" wrote in :

Greg Guarino wrote:

Now I need to learn how to keep it sharp. People recommended diamond
hones, but I see at least 5 "colors" (grits). Any tips as to which
one(s) I need?

It rather depends on what needs doing, wot? I use silicon carbide but
the same ideas apply...

Exactly - the corner chisel is just like any other chisel, so
you'd use the same grits as you would for the same task on a
regular chisel. Something pretty fine if you just need a light
honeing, otherwise work up thru the grits. Diamond hones are
good because you can get them in small sizes (with safe edges)
that easily fit the bevel. As dadiOH says, you can glue silicon
carbide sandpaper to popsicle sticks for the same result.

180/220/280 if I need to take out nicks, 400 & 600 to finish, rarely
up to 1000. Don't forget the backs.

I think this is one of those tools where you don't want to
touch the backs. Granted, the shape isn't as critical as
something like a Forstner bit, but I think I'd just work the
bevel, unless there was an obvious problem with the backs.

I would think silicon carbide on a block would work well for that,
sharpen both edges evenly & simultaneously.

It would be a weird shaped block. I'd do both sides seperately.

John

On 5/16/2015 11:45 AM, Greg Guarino wrote:

Now I need to learn how to keep it sharp. People recommended diamond
hones, but I see at least 5 "colors" (grits). Any tips as to which
one(s) I need?

I use the edge of an Arkansas stone to keep them honed.

Doing so religiously after every use, ten years have gone by with no
real need to expend any extra "sharpening" effort.

--
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Wood Shop: www.e-WoodShop.net
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KarlCaillouet@ (the obvious)

On 5/16/2015 12:45 PM, Greg Guarino wrote:


Now I need to learn how to keep it sharp. People recommended diamond
hones, but I see at least 5 "colors" (grits). Any tips as to which
one(s) I need?

Simple really. Just go down to the Town Hall and hone it on the corner
stone.
Glad I could help.