Author Topic: sharpening chisels  (Read 12138 times)

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Offline Tom Bainbridge

  • Posts: 1009
  • Limey Carpenter
sharpening chisels
« on: June 14, 2008, 06:03 PM »
i asked this in a uk forum but decided i might get a more open view from the (probably) larger FOG membership

BUT like large democracys, it can also mean a much wider range of views  ::)



ive not got japanese chisels. i sharpen my (western) chisels at 25 degrees then hone at 30 degrees, a double bevel

i am told that japanese chisels are sharpened and honed at the same angle



my three questions are

is this correct about japanese chisels

if it is correct, why do they do this (the japanese dont do anything by halves or for no reason)

is there any benefit in sharpening and honing my western chisels at one angle (in my case 30 degrees and a tormek makes it easy for me to do it)



im of course aware that it will mean a period of minor adjustment to my chiseling technique
Bromley, Kent. UK

aka dirtydeeds

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Offline tvgordon

  • Posts: 501
  • Springfield, Ohio
Re: sharpening chisels
« Reply #1 on: June 14, 2008, 06:37 PM »
I always thought the advantage of different angles was it made it easier to hone.  You only have to remove a very small section of metal with a super fine stone rather than the whole face.  The stouter angle should be a little more durable also.

I've sharpened my Japanese chisels the same as the others so I would also like to know if they are suppost to be sharpened differently.

Tom.

Offline TahoeTwoBears

  • Posts: 194
  • Sugar Bear - South Lake Tahoe, California, USA
Re: sharpening chisels
« Reply #2 on: June 14, 2008, 07:52 PM »
You might check this link. It's not all inclusive, but will give you an idea. You might want to call these folks as well. They're nice.

http://www.japanwoodworker.com/newswire.asp?content_id=11519

Mike

Offline Besttool

  • Posts: 34
Re: sharpening chisels
« Reply #3 on: June 14, 2008, 08:13 PM »

Offline Tom Bainbridge

  • Posts: 1009
  • Limey Carpenter
Re: sharpening chisels
« Reply #4 on: June 15, 2008, 06:02 AM »
thanks for the suggestions, ive contacted the japanese web site


underused

your reference to chipping tells me much about the extreme hardness of japanese chisel steel

my chisels do chip when i hit nails, but more often the edge is "mashed" at the point of nail strike

the "usual" argument about a short 30 degree secondary bevel being quicker as it requires less steel to be removed to restore the edge is more about traditional hand sharpening on oil stones


my question about sharpening and honing at the same angle has arrisen because i use a tormek grinder, so the argument about less steel to be removed isnt an issue because the tormek is so quick anyway

 
« Last Edit: June 15, 2008, 11:22 AM by dirtydeeds »
Bromley, Kent. UK

aka dirtydeeds

Offline Frank-Jan

  • Posts: 991
  • Dutch Canadian living in Belgium
Re: sharpening chisels
« Reply #5 on: June 21, 2008, 09:49 AM »
This is what the tormek manual says about secondary bevels:

Quote from:  Tormek manual
Secondary bevel?
Some people recommend that you should put a secondary bevel (or microbevel) on your plane irons and wood chisels. The reason is that the honing work after the grinding is quicker since you do not neet to hone the entire surface of the bevel, just the smaller new bevel at the tip.
For wood chisels there  is a drawback with a secondary bevel since you do not have the support of the large original bevel to control the cutting in the wood.
For plane irons, a secondary bevel increases the risk that the heel of the secondary bevel will touch the wood and cause chattering.

Since the grinding and honing of the entire bevel with the tormek method is an easy and fast operation, there is no need for a secondary bevel. With a single bevel, you can set exactly the angle that you want and easily maintain it at every grinding and honing.

I don't have a tormek, but I have the similar Jet sharpener ( link I sharpen most of my chisels to a 28? bevel and hone on the leather wheel with the compound, but for the back of the chisel I use a stone. They do end up with secondary bevels, if I have to freshen up the edge on site, but every once in a while I regrind them all on the wet sharpener.

BTW, when I was looking for the download link for the tormek manual (25 MB pdf, which isn't available anymore from their website, unless you register and give a tormek serial number) I saw they have a new straight edge guide which clamps the chisel from underneath the guide, so you don't have to fiddle with the thumbscrews anymore to get them exactly parallel, I hope that jig works with the jet aswell (most of them do, but for some reason the truing jig with the thumbscrews doesn't (so I read, haven't tried it myself, I have the Jet version))
Link to new squaring jig
« Last Edit: June 21, 2008, 09:54 AM by Frank-Jan »

Offline Steveo48

  • Posts: 305
Re: sharpening chisels
« Reply #6 on: August 16, 2008, 11:31 PM »
When I was younger I got all caught up in my underware making sure I got those angles just right.  Somewhere along the line I discovered it really wasn't (for me) a critically important item.

Then I discovered I didn't need my expensive Arkansas stones.  I just needed fine sand paper, light oil and a metal table top (or scrap of melamine) to make sharpening a lot easier and faster.

Steve

Offline Les Spencer

  • Posts: 487
Re: sharpening chisels
« Reply #7 on: August 17, 2008, 07:46 PM »
According to the Tormeck manual,

Secondary bevel ?
Some people recommend that you should put a secondary bevel ( or microbevel ) on your plane
irons and wood chisels. The reason is that the honing work after the grinding is quicker since
you do not need to hone the entire surface of the bevel, just the smaller new bevel at the tip.
For wood chisels there is a drawback with a secondary bevel since you do not have the support
of the large original bevel to control the cutting in the wood.
Since the grinding and honing of the entire bevel with the Tormek method is an easy and fast
operation, there is no need for a secondary bevel. With a single bevel, you can set exactly the
angle that you want and easily maintain it at every grinding and honing.
Reduced support length
with a secondary bevel
on a wood chisel.
Support length
with a monobevel.
Hone the back free hand. Hold
the tool so that it is at a tangent
to the wheel.
Do not hold the tool at a steeper
angle than the tangent! The tip
will be rounded off.
Edge angle
Plane irons, wood chisels and spoke shave blades are
usually ground with a 25? edge angle ( a ).
If you need to work delicate details with a wood chisel in
soft wood, you can decrease the edge angle down to 20?.
If you work in hard wood and when using a mallet, you
must increase the edge angle to 30?.

Looks like your assumtion was correct. No secondary required when using a Tormeck.

If you want to register so you can see the manual, you can do so by clicking older model, then put anything in model name and I put in 1986 as purchase date and used as dealer name.
Les (near Indy) XL

Offline Tom Bainbridge

  • Posts: 1009
  • Limey Carpenter
Re: sharpening chisels
« Reply #8 on: August 19, 2008, 03:04 PM »
i have changed the way i sharpen my chisels with the tormec

i now use a single bevel, because its much quicker



HOWEVER

it does alter the position of the chisel against your marked (scribed) line VERY VERY slightly as opposed to a dual bevel

beginers always postition the chisel on the line, then strike


wrong wrong and thrice wrong

you ALWAYS set the chisel SHY of the line because it works as a single bevel wedge (although extremely sharp)

setting the chisel shy of the line, then striking it (the bevel) forces it TO the line


doing it the beginers way (setting the chisel ON the line) forces the chisel beyond the line

and a hinge will fall out of its pocket because it is too ong OR a mortice will be too long




done correctly (chisel set shy of the line) prior to strike

and a hinge will sit tight in its pocket without screws and a mortice will be tight


its only a case of a 64th (at both ends)

making a total length difference of a 32nd

this is nearly a milimeter, and the hinge will fall out



"so what", you might say on paint grade work


but on stain grade (or even more difficut on varnish grade) work

it looks like cowboys did the job
Bromley, Kent. UK

aka dirtydeeds

Offline BIP

  • Posts: 34
Re: sharpening chisels
« Reply #9 on: August 19, 2008, 11:43 PM »
My bench and paring chisles are hollow ground via a Delta vertical wet wheel and honed on 3M diamond plates.  I grind my mortising and timber framing chisels on a Makita horizontal wet wheel because I like the extra metal behind the cutting edge when using heavier mallets.

It may have been already covered, but Japanese chisels can be had in blue or white steel.  The blue can be honed to a finer edge than white steel, but it is also more brittle than white steel. 

Offline ktcruickshank

  • Posts: 4
Re: sharpening chisels
« Reply #10 on: August 20, 2008, 07:25 PM »
Yes Tom: What I'm hearing from guys like master artisan Craig Vandall Stevens is that the sharpening angle for Western or Japanese chisels is determined in the same way. In fact, Craig, like others here at FOG say that the numeric angle is less important than the result you are trying to achieve. The lower the angle ("sharper") the easier to cut, but the more fragile the edge. So for harder woods a steeper angle might be more durable. Finding the balance for your situation is a matter or trial and error and of course experience. Craig explains his approach here in this video: http://woodtreks.com/an-introduction-to-japanese-chisels/74/ (this video is focused on Japanese chisels, but the sharpening angle discussion does indeed applies to western blades too.) Maybe this will help. Keith (www.woodtreks.com)