 | |  | |  | |  | |  | |  | |  |
Preparing the bottom surface of the chisel.
Introduction.
Probably the most time consuming job when getting a chisel ready for fine cabinet making is working on the bottom surface. A
chisel, like timber is rarely flat when it arrives from the manufacturer, some are convex whilst other are concave, and I don’t mean
just a small amount.
The Lie-Nielson chisels arrived the in the best condition requiring a small amount of work, whilst the Japanese chisels were well out
of shape.
Utter basics. So what I am aiming for when working on the bottom surface.
a in the case of a Japanese chisel, some of the hollow is still present.
b completely flat across the chisels width.
c fractionally concave along the chisels length.
d I am also aiming to get rid of the manufacturers machine marks and eventually replace these with a mirror like finish on my
8000 grit Japanese water stone.
FtBtm01a
my reference 12mm complete chisel 020.jpg
Introduction.
Probably the most time consuming job when getting a chisel ready for fine cabinet making is working on the bottom surface. A
chisel, like timber is rarely flat when it arrives from the manufacturer, some are convex whilst other are concave, and I don’t mean
just a small amount.
The Lie-Nielson chisels arrived the in the best condition requiring a small amount of work, whilst the Japanese chisels were well out
of shape.
Utter basics. So what I am aiming for when working on the bottom surface.
a in the case of a Japanese chisel, some of the hollow is still present.
b completely flat across the chisels width.
c fractionally concave along the chisels length.
d I am also aiming to get rid of the manufacturers machine marks and eventually replace these with a mirror like finish on my
8000 grit Japanese water stone.
FtBtm01a
my reference 12mm complete chisel 020.jpg
How do I check for flatness
(fractionally concave) in the
chisels length?
I used one side of my 150mm
(6”) engineers try-square that I
have checked with my
engineers straight edge and
found to be perfectly flat. I
marked this with red marker
pen so there would be no
confusion as to which side of
the try-square I was using.
(fractionally concave) in the
chisels length?
I used one side of my 150mm
(6”) engineers try-square that I
have checked with my
engineers straight edge and
found to be perfectly flat. I
marked this with red marker
pen so there would be no
confusion as to which side of
the try-square I was using.
This surface is then regularly used during the ‘flattening’ process. I place the bottom of the chisel in contact with this surface with
a light source behind. My light source of preference is daylight, simply by looking out of my workshop window, or in the evening
having a fluorescent lamp at the back.
During the flattening process I am aiming to form a CONCAVE SURFACE so that I can see a glimmer of light around the
centre point, with the ‘heel’ and sharpened end of the chisel, in contact with the flat surface of the try-square.
I have highlighted the above paragraph simply because it is the key in the process of preparing the chisel bottom. It needs to be
fractionally concave in the chisels length, and the bottom surface will require regular checking especially when using the very course
glass paper in the initial process.
a light source behind. My light source of preference is daylight, simply by looking out of my workshop window, or in the evening
having a fluorescent lamp at the back.
During the flattening process I am aiming to form a CONCAVE SURFACE so that I can see a glimmer of light around the
centre point, with the ‘heel’ and sharpened end of the chisel, in contact with the flat surface of the try-square.
I have highlighted the above paragraph simply because it is the key in the process of preparing the chisel bottom. It needs to be
fractionally concave in the chisels length, and the bottom surface will require regular checking especially when using the very course
glass paper in the initial process.
FtBtm03a
Equipment required for forming the fractionally concave bottom surface.
To form the initial fractionally concave surface I use an off-cut 40mm (1. 9/16”) thick that was left over when fitting a new top to
some kitchen base units. This was checked with my engineers straight edge and found to be perfectly flat.
I then secure a strip of 80 grit glass paper with cramps. The width of the strip is around ½ the chisel’s length.
To form the initial fractionally concave surface I use an off-cut 40mm (1. 9/16”) thick that was left over when fitting a new top to
some kitchen base units. This was checked with my engineers straight edge and found to be perfectly flat.
I then secure a strip of 80 grit glass paper with cramps. The width of the strip is around ½ the chisel’s length.
FtBtm04a
because the images are not as clear when using this deep green surface, I have taken all the photographs using a piece of light
coloured plywood.
coloured plywood.
Forming a fractionally concave surface on the chisel bottom.
My method of approach will depend on the width of the chisel.
1 Removing the convex bottom surface on chisels that are 3mm(1/8") wide and up to 9mm(3/8”)wide.
I position the chisel so that is centred on the glass-paper, with pressure being exerted by a couple of fingers as shown. Keeping the
‘heel’ and tip off the chisel off the glass paper, the chisel is moved in the direction shown.
and slowly moved along the glass paper, checking ever dozen strokes or so on the side of the try-square, so that you form that
fractionally concave surface.
If I was working on a batch of chisel I would certainly add some protection to my finger because otherwise they would end up
rather tender. This 3mm(1/8") wide chisel took around 6 minutes to remove the convex surface and give me a fractionally concave
surface.
My method of approach will depend on the width of the chisel.
1 Removing the convex bottom surface on chisels that are 3mm(1/8") wide and up to 9mm(3/8”)wide.
I position the chisel so that is centred on the glass-paper, with pressure being exerted by a couple of fingers as shown. Keeping the
‘heel’ and tip off the chisel off the glass paper, the chisel is moved in the direction shown.
and slowly moved along the glass paper, checking ever dozen strokes or so on the side of the try-square, so that you form that
fractionally concave surface.
If I was working on a batch of chisel I would certainly add some protection to my finger because otherwise they would end up
rather tender. This 3mm(1/8") wide chisel took around 6 minutes to remove the convex surface and give me a fractionally concave
surface.
FtBtm 05a.JPG
FtBtm08 6aJPG
and use around
45mm of the glass
paper.
45mm of the glass
paper.
FtBtm03a
A key part of the
process is
checking after a
dozen or so
strokes until you
obtain that
fractionally
concave surface.
process is
checking after a
dozen or so
strokes until you
obtain that
fractionally
concave surface.
2 Removing the convex bottom surface on chisels that are wider than 9mm(3/8”)
Holding the handle very lightly, and pressing firmly with two fingers, I push the chisel in one direction only, keeping the 'front edge'
and heel of the blade off the glass paper.
As before regularly check on the engineers try-square how the operation is progressing. Unlike working with the narrow chisels,
this can be a time consuming process. The aim again is to get that fractionally concave surface in the blades length.
Holding the handle very lightly, and pressing firmly with two fingers, I push the chisel in one direction only, keeping the 'front edge'
and heel of the blade off the glass paper.
As before regularly check on the engineers try-square how the operation is progressing. Unlike working with the narrow chisels,
this can be a time consuming process. The aim again is to get that fractionally concave surface in the blades length.
FtBtm 7a.JPG
3 Japanese chisels.
If you own a Japanese chisel you will be aware that on purchase or regular grinding and sharpening, the flattened area of the chisel
near the front end will become unusable because if you kept grinding away you would end up in the hollowed out area.
The image below shows the bottom of one of my Japanese chisels. The pencil is resting on the flattened area
If you own a Japanese chisel you will be aware that on purchase or regular grinding and sharpening, the flattened area of the chisel
near the front end will become unusable because if you kept grinding away you would end up in the hollowed out area.
The image below shows the bottom of one of my Japanese chisels. The pencil is resting on the flattened area
FtBtm 8a
and the same chisel after it has been
worked on.
FtBtm9
worked on.
FtBtm9
and the same chisel
after I have exposed
more metal at the front
end.
Probably around
6mm(1/4")
after I have exposed
more metal at the front
end.
Probably around
6mm(1/4")
Increasing the useable area at the front end of a Japanese chisel.
Starting with Japanese chisels that are between 3mm(1/8") and 9mm(3/8”) wide.
The way to resolve this situation is to is ‘re-flatten’(fractionally concave) the bottom and expose more metal at the front end. For
my narrow chisels I will be aiming to remove most of the hollowed area so that I never have to repeat the process again.
With the wider chisels, because this process takes much longer, I am looking at an area of metal at the 'front edge' that is in the
region of 6mm(1/4”) long.
I secure a strip of 80 grit glass paper that is around 75mm(3”) wide to the flat surface. Notice that the width of the glass paper is
wider than used in the previous process.
And the chisel is moved in the direction of the arrow so that that ‘heel’ remains on the glass paper and finger pressure is at the
front end.
Starting with Japanese chisels that are between 3mm(1/8") and 9mm(3/8”) wide.
The way to resolve this situation is to is ‘re-flatten’(fractionally concave) the bottom and expose more metal at the front end. For
my narrow chisels I will be aiming to remove most of the hollowed area so that I never have to repeat the process again.
With the wider chisels, because this process takes much longer, I am looking at an area of metal at the 'front edge' that is in the
region of 6mm(1/4”) long.
I secure a strip of 80 grit glass paper that is around 75mm(3”) wide to the flat surface. Notice that the width of the glass paper is
wider than used in the previous process.
And the chisel is moved in the direction of the arrow so that that ‘heel’ remains on the glass paper and finger pressure is at the
front end.
FtBtm10
I also allow the chisel
to overlap the edge like
this.
to overlap the edge like
this.
FtBtm11
FtBtm03a
As a reminder a key
part of the process is
checking after a
dozen or so strokes
to check that the
bottom surface is
fractionally concave.
part of the process is
checking after a
dozen or so strokes
to check that the
bottom surface is
fractionally concave.
Now sometimes I find that the concave surface has been removed and therefore I return to using a strip of glass paper that is
around ½ the width of the chisel then resume the process.
around ½ the width of the chisel then resume the process.
And for chisels over 9mm wide.
Again finger pressure near the front end of
the chisel and pushed in the direction of the
arrow.
FtBtm12
Again finger pressure near the front end of
the chisel and pushed in the direction of the
arrow.
FtBtm12
And for chisels over
9mm wide.
Again finger pressure
near the front end of
the chisel and pushed
in the direction of the
arrow.
9mm wide.
Again finger pressure
near the front end of
the chisel and pushed
in the direction of the
arrow.
FtBtm13
I also allow the
chisel to have it
'front edge' off the
glass paper.
chisel to have it
'front edge' off the
glass paper.
Having obtained the desired length of metal
at the front end of the chisel, I want to
replace the deep scratches left by the 80
grit glass paper that were parallel to the
cutting edge, with ones that are running
parallel to the length of the blade by
moving it in the direction of the arrow.
FtBtm14
at the front end of the chisel, I want to
replace the deep scratches left by the 80
grit glass paper that were parallel to the
cutting edge, with ones that are running
parallel to the length of the blade by
moving it in the direction of the arrow.
FtBtm14
Having obtained the
desired length of
metal at the front end
of the chisel, I want
to replace the deep
scratches left by the
80 grit glass paper
that were parallel to
the cutting edge,
with ones that are
running parallel to
the length of the
blade by moving it in
the direction of the
arrow.
desired length of
metal at the front end
of the chisel, I want
to replace the deep
scratches left by the
80 grit glass paper
that were parallel to
the cutting edge,
with ones that are
running parallel to
the length of the
blade by moving it in
the direction of the
arrow.
Summary so far.
1
All the chisel will either have been bought with a fractionally concave bottom surface, or I have formed one using the methods
described.
2
The Japanese chisels have had the cutting edge increased at their front end
1
All the chisel will either have been bought with a fractionally concave bottom surface, or I have formed one using the methods
described.
2
The Japanese chisels have had the cutting edge increased at their front end
The next task is to remove
the deep 80 grit scratches
formed in the previous
operations, and to work on
the chisels that arrived
fractionally concave.
For this I used 70mm(2 ¾”)
wide 240 grit 'wet and dry'
paper and I only move the
chisels in one direction
irrespective of the width of
the chisel. As before firm
pressure is exerted at the
front end.
the deep 80 grit scratches
formed in the previous
operations, and to work on
the chisels that arrived
fractionally concave.
For this I used 70mm(2 ¾”)
wide 240 grit 'wet and dry'
paper and I only move the
chisels in one direction
irrespective of the width of
the chisel. As before firm
pressure is exerted at the
front end.
FtBtm15
and its not long even on the wider chisels that the deep 80 grit marks are replaced with 240 grit marks.
Having reached this stage with the glass paper and 240 grit 'wet and dry' paper I now revert to my Japanese water stones.
Having reached this stage with the glass paper and 240 grit 'wet and dry' paper I now revert to my Japanese water stones.
FtBtm17.JPG
Firstly the 800 grit stone
I secure my 800 grit water stone in my sharpening station, form a slurry with the 1200 grit stone, mark a pencil line around 15mm
(5/8”) from one edge, and position the chisel as shown
I secure my 800 grit water stone in my sharpening station, form a slurry with the 1200 grit stone, mark a pencil line around 15mm
(5/8”) from one edge, and position the chisel as shown
and the aim is to move the chisel in the direction shown below the complete length of the water stone with firm finger pressure on
the front end of the chisel.
the front end of the chisel.
FtBtm018.jpg
The whole process is then repeated on the 1200 and 8000 grit water stones.
with the finger or thumb pressure exerted as before at the front of the chisel like this
with the finger or thumb pressure exerted as before at the front of the chisel like this
It does not take long before the 240 grit marks are replaced with finer marks from the 800 grit stone. As a reminder once I have
travelled twice along one edge, that edge of the stone is not used again until flattened.
In this case the stone is rotated 180 degrees and the opposite edge used in a similar manner. The stone is then flattened as described
in the chapter Water stone maintenance
travelled twice along one edge, that edge of the stone is not used again until flattened.
In this case the stone is rotated 180 degrees and the opposite edge used in a similar manner. The stone is then flattened as described
in the chapter Water stone maintenance
FtBtm019.jpg
or this
ending up with a mirror like finish on the bottom surface that is fractionally concave.
FtBtm021.jpg
A few notes.
My first experience of using and owning a quality chisel was when I purchased some Japanese laminated chisels, both the ‘striking’
type and a couple of the paring chisels. They are superb but required a serious amount of work removing metal before they were fit
for dovetailing.
A few years down the line, Lie-Nielson brought to market a chisel in the European style. Instead of a blade length of around 60mm
for the Japanese chisels the Lie-Nielson’s were in the region of 90mm , and in a similar price range. I purchased two of these and
they match the quality of the Japanese chisels
They still however require the excess metal at the sides of the chisel removing before they are suitable for removal of the waste
between the 'tails' of a dovetail joint. All of this can be seen in the images on this web site.
In 2008 I purchased some bevel edge chisels manufactured by Blue Spruce Toolworks from USA. Unlike all other chisels that I am
personally aware of, they are designed for the removal of the waste between the tails. They are made from A2 steel and match the
quality of the two previous brands.
Having spend so much time over the years on the Japanese and Lie-Neilson chisels to get them suitable for dovetailing
I have no desire to do so with the introduction of the Blue Spruce bevel edge chisels. The are superb.
My first experience of using and owning a quality chisel was when I purchased some Japanese laminated chisels, both the ‘striking’
type and a couple of the paring chisels. They are superb but required a serious amount of work removing metal before they were fit
for dovetailing.
A few years down the line, Lie-Nielson brought to market a chisel in the European style. Instead of a blade length of around 60mm
for the Japanese chisels the Lie-Nielson’s were in the region of 90mm , and in a similar price range. I purchased two of these and
they match the quality of the Japanese chisels
They still however require the excess metal at the sides of the chisel removing before they are suitable for removal of the waste
between the 'tails' of a dovetail joint. All of this can be seen in the images on this web site.
In 2008 I purchased some bevel edge chisels manufactured by Blue Spruce Toolworks from USA. Unlike all other chisels that I am
personally aware of, they are designed for the removal of the waste between the tails. They are made from A2 steel and match the
quality of the two previous brands.
Having spend so much time over the years on the Japanese and Lie-Neilson chisels to get them suitable for dovetailing
I have no desire to do so with the introduction of the Blue Spruce bevel edge chisels. The are superb.
If you have benefited from this web page and would like to contribute to good causes listed below are charities of my
choice.
The Alzheimers Association. www.justgiving.com/hand-cut-dovetails
Water aid www.justgiving.com/hand-cut-dovetails1
Dreams come true www.justgiving.com/hand-cut-dovetails2
Help for heroes www.justgiving.com/hand-cut-dovetails3
The Wounded Warrior Project www.firstgiving.com/fundraiser/hand-cut-dovetails/alan
choice.
The Alzheimers Association. www.justgiving.com/hand-cut-dovetails
Water aid www.justgiving.com/hand-cut-dovetails1
Dreams come true www.justgiving.com/hand-cut-dovetails2
Help for heroes www.justgiving.com/hand-cut-dovetails3
The Wounded Warrior Project www.firstgiving.com/fundraiser/hand-cut-dovetails/alan