hi I'm James Hamilton from stumpy nubs
woodworking journal and today we'll
answer some of the most common questions
people ask about diamond sharpening
stones
I know our craft is full of strange and
diverse personalities but there's some
lunatics out there who actually enjoy
sharpening their tools they save all
their blunt chisels and playing irons
until the end of the day then they hone
them in some giant moment of Zen I
believe we should keep people like that
away from sharp objects to me there are
a few tasks in the workshop as
mind-numbingly tedious as sharpening
luckily we live in the modern era where
we can find any number of products
designed to make the task easier today I
want to talk about diamond sharpening
plates or stones perhaps they are in a
big mystery to you but for a lot of
people they're confusing as heck here
are some of the questions they may come
up in your hunt for the right diamond
stone I think it's a matter of opinion
but for me it comes down to two things
they're easy to maintain and they work
quickly unlike traditional stones a
diamond plate doesn't become dished out
as you use it that means you don't have
to reflect it between uses
and since diamonds are the hardest
material on earth they cut steel fast
they can even be used to sharpen carbide
router bits and cutters nope
all the stones I have ever used are
covered with man-made micro diamonds
there are a couple of different
processes that may be used to create
them but it generally involves chemicals
gases carbon and heat diamonds are
literally grown on a substrate in a
special chamber then they're sifted to
separate them by grit size and then
they're attached to a plate for your
sharpening convenience yep some Diamond
stones use what are called poly
crystalline diamonds while others use
mono crystalline diamonds the surface of
polycrystalline diamonds are very rough
they're covered with all these tiny
points and sharp edges these edges
fracture away during use which expose
new edges this is great for fine
polishing pastes but not so much with
diamond sharpening stones because the
diamonds get smaller as they break up
so you're 300 grit stone will quickly
become something that's entirely
different over time that's why the
better quality diamond stones are made
with monocrystalline diamonds
these are more expensive to produce but
they maintain their size and shape
during use for a very long
absolutely it does cheaper brands merely
sprinkle the diamonds onto a layer of
adhesive problem with this method is
that the overall stone is only as good
as the quality of the adhesive so they
usually have a very short lifespan those
of these diamond stones that you get
alike Harbor Freight in places like that
good diamond stones are electroplated a
metal plate is dipped into a solution of
heated nickel and diamonds then an
electrical current is passed through the
solution which causes it to bond with
the plate this process actually embeds
about two-thirds of the diamond in the
nickel layer making it very difficult to
remove they're kind of like little
icebergs with just the points sticking
out electroplated diamond stones have a
far longer lifespan than those made with
adhesives the least expensive diamond
stones feature diamonds embedded or
glued to a thin metal plate which is
then in turn attached to a plastic block
these are moulded usually not machined
flat others attach their thin metal
plate to a thicker metal base but
frankly it still defeats the whole
purpose a good diamond plate should be a
single plate of Steel it should be
precisely flat less than a thousandth of
an inch from end to end because the
process of embossing the Diamonds will
slightly decrease the level of flatness
the plate itself should be machined to
about five ten thousandths of an inch if
you hope to achieve a thousandth of an
inch in the end product only then can
you be sure that it will be flat and
only by creating the stone from a single
piece of steel can you be sure adhesives
and moisture and corrosion won't affect
that flatness over time some companies
say you can use their stones dry while
this won't harm the diamonds it's rarely
a good idea in my opinion as material is
removed from your blade it has to go
somewhere a lubricant will carry it away
so that it won't build up between the
diamonds which would quickly cause them
to stop cutting you can if you have a
cheap plastic one but we've already
talked about why those stones aren't
worth your time some companies recommend
water I really think that's a bad idea
and I'm not alone in that theory it's
never a good idea to introduce water
into metal unless you're absolutely sure
you can get it
lately dry every time that's easy with a
chisel or a planer
iron because you can just wipe it dry
but it's not so easy with diamond stones
water's likely to remain deep inside the
grit or even seep into any tiny cracks
and the nickel used to embed the
diamonds getting between that steel
substrate and the diamonds themself can
lead to corrosion where you definitely
don't want that problem is compounded if
your stone has layers instead of being
just one plate because guess where that
moisture is going to go over time
between the layers which is going to
compromise this flatness that depends
fine stones like a thousand grit feature
diamonds that are about fifteen microns
in size but about two-thirds of that
diamond is embedded in the stone that
means that the valley is between your
diamonds are only about five microns
deep now according to the material
safety data sheet for wd-40 it leaves a
film of 17 microns needless to say
that's thicker than the valleys are deep
so while light oils like wd-40 or even
kerosene may be fine for very coarse
stones they're too thick for fine stones
your iron is just going to skid across
the top and it's not going to sharpen
effectively I used the trend lapping
fluid it was developed by the
engineering industry decades ago
specifically for Diamond abrasives it's
a petroleum product so there's no risk
of rust yet it's also water soluble so
it's easy to clean up and it's just the
right consistency if I had one complaint
is that the fluid is a little bit pricey
but a very small bottle is gonna last
you a long time I know some people like
to poopoo this whole thing and they say
just use the wd-40 or the kerosene or
the water but all I know is for a couple
of cents per use I know my diamond is
going to be cutting at peak performance
with the lapping fluid I use a three
hundred grit stone to create a new bevel
and then I follow up with thousand grit
and then as a final step I use a leather
strop to polish the edge why three
hundred one thousand because those
happen to be the two grits on my
double-sided stone frankly it doesn't
matter as much as you think three
hundred grit is nice because it works
faster than say 600
but it's not so coarse that you'll have
to spend all day on the thousand grit
side to remove all those 300 grit
scratches a thousand grit is sharp
enough especially if you follow it up
with the strop I know some people really
like to fuss over their grits and water
stones can go up into the tens of
thousands but what is an abrasive
material and after a couple of strokes
your twenty thousand grit edge is going
to be worn down to that thousand grit
anyway if a thousand grit followed by a
light strapping is enough to shave hair
off your arms it's sharp enough to shave
wood fibers yep these things aren't
cheap so why buy more than you need of
course there are some great diamond
accessories on the market for special
applications and I use them as needed in
fact we've made a couple of videos
recently about how to sharpen router
bits and Forstner bits things like that
you can find those videos over at stubby
nubs calm but generally straight edge
tools and a lot of other things can be
sharpened with just one double-sided
stone and a leather strop the bottom
line is if you sharpen your tools by
hand you may want to check into Diamond
stones they require almost no
maintenance and they cut faster if you
do decide to buy Diamond stones insist
that they're made with monocrystalline
diamonds that are electroplated to the
surface of a single piece of machined
steel no glue no layers also avoid using
your stones dry stay away from water and
if you're fine grits are cutting slowly
it's probably the type of lubricant that
you're using finally you can get by with
just one stone
three hundred grit and grit or something
similar and a leather strop for just
about every woodworking tool thanks for
watching I hope you learned something be
sure to check out the latest issue of
stumpy nubs woodworking journal which is
full of great tips tricks and tutorials
designed to make you a better woodworker
you can read and subscribe for free at
stumpy tubs calm happy honing