This video actually starts six years ago,
way back in 2014. I've been wanting to make a kitchen knife for as long as I can remember...
But in order to do it justice I figured I had to really learn how to use a kitchen knife first!
So I made my first prototype and then I took it with me to cooking school!
Here I got to learn knife skills from professional chefs, learn basic butchery,
practice using my knife a bunch and also get feedback on the knife from a number of
professional chefs, who I lent it to for periods of a couple of weeks at a time.
All of this testing and practice was hugely informative and really invaluable, I found
a bunch of things that I wanted to change with the knife including the thickness of the blade,
the shape of the heel, and also the shape of the handle a little bit.
But unfortunately I never found time to work on it until the middle of 2019,
almost five years later. I guess at least no one can accuse me of rushing into things!
So here we are in the middle of 2019 and I'm finally ready to have another crack at
this knife. The first thing that I do is take the template for the original knife,
trace it out on a piece of paper and then start making the modifications that I wanted to try.
With the template redrawn I scanned it, printed it out so i could have as many copies as I wanted,
and then got ready to copy it onto a piece of
steel. To do this I cut out the outline with a pair of scissors,
and then simply used a permanent marker to trace the outline onto the steel. I then center punched
the middle of the handle pin holes and now we're finally ready to start making a knife!
First I cut the piece of steel stock to length on the bandsaw.
Then I used the bandsaw again, to rough cut the outline of the knife. Now that I've roughed out
the shape on the bandsaw I'm ready to take it over to the grinder to refine the outline.
This 36 grit ceramic grinding belt makes quick work of refining the shape!
The only part that I couldn't fully get to on the grinder was just in behind the heel,
so I finished shaping this area with a file. All the burrs around the edges of
the profile were removed by lapping the blank on some sandpaper mounted to a surface plate.
With the blank now fully rough shaped I could move on to drilling the pin holes using a drill press.
Looking back I'm not sure why I'm not using a clamp here, don't be me,
make sure you use a clamp on the drill press!
Because kitchen knives are so long and thin, they tend to warp if you heat treat them after grinding
in the bevels. To avoid this I heat treated the blade while it was still completely flat,
and then I'll grind the bevels in after it's been heat treated.
First I wrap the blade in an envelope made from stainless steel foil,
this is to protect it from oxygen during the heat treatment process, then I carefully put
it into the preheated kiln. Once the blade is heated up to 1775 degrees fahrenheit,
it's kept there for 35 minutes. After this it's ready to be removed and quenched in still air.
Because the A2 tool steel that I'm using has about 5 percent chromium in it,
it doesn't require a fast oil quench in order to harden.
Letting it cool in still air is more than enough to fully harden it.
After it's cooled to room temperature I can cut open the stainless steel envelope
and have a look at the blade for the first time! You can see these
really cool oxide colours that have formed on the outside of the blade.
Now it's time for the first temper cycle, this reduces the hardness of the blade a little bit,
but in return I get a lot more toughness. In this case I'm tempering it at 400 degrees fahrenheit
for two hours. After the first temper it's time for the sub-zero treatment in liquid nitrogen.
This takes any remaining retained austenite in the steel and converts
it to a harder and more useful structure called martensite. The subzero treatment
generally raises the hardness again by at least one to two rockwell points
After the blade has warmed back up to room temperature it's time for the second and
final temper cycle! After all those ups and downs I clean the oxide layer off the blade
with sandpaper, then I can test the hardness. The tester shows 62 Rockwell 'C' which is perfect.
Now it's time to start grinding in the bevels! To give myself a guide to work to I cover the edge
of the knife in permanent marker, and then score a line down the middle of the blade using my height
gauge. For this knife I want to do a flat grind that extends all the way to the rear of the tang,
this means that I don't have a place to put any bolts or screws so to hold the
blade onto the grinding fixture so I actually use a couple of drops of superglue instead.
It's been a while since I fully hand ground a blade bevel, so to begin with I just took it slow.
The first side actually took me about an hour and a half, just because I was being so careful.
First I rough ground the blade with a 60 grit ceramic belt,
and then I semi-finished it using a 120 grit aluminum oxide belt. I broke the super glue
bond with a quick smack from a hammer, and then you can see the first bevel is finished!
The second side went much more quickly because I was feeling a lot more confident
and I was happy to lean in on the blade a bit more.
To keep the heat low, and make sure that I don't ruin the heat treatment of the blade, I regularly
dipped the blade and the entire grinding jig into my bucket of water to keep it cool!
It's already looking pretty good, but now it's time to make it even better and move
on to hand finishing! To make hand sanding this hardened steel much easier, I use special stones
called 'mold polishing stones'. These are like tiny sharpening stones that are designed to
wear away as you use them, constantly exposing fresh abrasive so they cut quickly! Using these
stones requires different techniques than using sandpaper, but now that I've gotten used to them
they allow me to hand finish a knife in about half the time it would take using sandpaper.
Hand finishing a blade this size to a satin finish is still a job that requires care and patience
though! Here you can see I'm using a red permanent marker to highlight the scratches that I find
during inspection, to make sure that I get every single little one during the sanding process.
Now that I've hand sanded the blade to a relatively parallel 600 grit finish
I decided to try a new technique, which is to use an abrasive loaded cork belt
to put on the final satin finish. If I end up making a lot of these knives then
completely hand sanding all of them is going to destroy my hands, and wrists, and elbows
so I have to try and find better, smarter, ways to do things if I can.
The final finish from the cork belt is okay, it's not as good as what I
would do completely by hand, but I think with some practice I'll get better at it.
With the blade finished now I can move on to working on the handle scales!
Luckily I already have some G10 glued up ready for use in my Resolute knives,
so I can just cut a chunk of this in half and then get straight to work!
I lap the inside of the handle scales on sandpaper to make sure they're perfectly flat,
then I join them together temporarily with a couple of dots of superglue. This allows me to
work on the two halves simultaneously without ever worrying about them becoming misaligned.
With the outline of the tang drawn onto the G10 I'm able to head over to the drill press
to drill the pin holes. Those of you with keen eyes will see that I'm actually showing these
operations out of order, this is just because it makes more sense to show it this way.
With the pinholes drilled, and the outline of the tang marked onto the G10, I'm ready
to start grinding it to shape! I realized pretty quickly that black permanent marker
was not a good choice for marking the outline, so I went back and re-did it with a wax pencil.
A good respirator is essential when using the belt grinder,
you do not want to be breathing in this dust...
With the rough shaping done I can now work on the front of the scales.
This part will be inaccessible once I've glued them to the knife, so I have to do all of the
shaping before they're glued on. Normally I use a little jig to put the angle on these,
but I decided to try free-handing it and see how it would go. It actually went pretty well!
A little finish sanding by hand with some 220 grit sandpaper and they're ready to go!
To get the handle scales apart I use a razor blade as a wedge, just hammer it in between them,
and then I lap all the super glue residue off.
I'm left with two perfectly identical handle scales.
After counter-boring the pin holes to accept the heads of the Corby bolts I'm ready to join
everything together with the blade! I start by precisely mixing up some marine grade epoxy,
then carefully degreasing the blade and handle scales using acetone.
All the parts are coated in a thin layer of epoxy, the corby bolts are fitted,
and then everything is tightened up so the epoxy can cure overnight.
I have to be very careful to make sure that I get all of the wet epoxy off the blade,
once it's cured it's going to be very difficult to remove!
The next day the epoxy is fully cured and I can finish shaping the handle and tang.
Once the outline of the handle scales is ground flush with the tang
I can start actually shaping the handle scales. To do this I'm using a 120 grit aluminum oxide belt.
I have to be really careful not to scratch the blade while I'm working on the handle scales!
The original idea was to have quite a rounded handle shape, with just a couple of flat facets.
But once I'd done this I found that it looked really quite boring. So I ended up
spending more time on the grinder and just trying to get a shape that I really liked.
I ended up spending about an hour and a half just slowly working on the handle,
making it more and more angular. The more angular it got, the more I liked it! Working
on hand scales like this is really different from working on them in CAD. You're able to feel the
handle shape as you progress and work on it, and because of that you can be a lot more adventurous.
This hands-on development and refinement process is one of the primary reasons why
I do all of my prototypes by hand rather than using CNC for them.
With the majority of the handle shaping done on the grinder I then
go in and tune things up by hand, just to get everything exactly as I want it.
Things are looking pretty good now, though it's a bit hard to see the final shape of
the handle scales in this state. Once everything is clean you'll be able to see it a lot better!
The final step that really makes this blade into a knife is sharpening!
To sharpen it I use my custom made variable speed sharpening system.
I designed and made this system a few years ago, and I've used it just about every day since!
I rough in the edge using a 600 grit electroplated CBN wheel,
and then finish it by stropping on an MDF wheel loaded with 1200 grit CBN paste.
As you can see here, the final edge is terrifyingly sharp!
No kitchen knife video would be complete without a demonstration on some poor tomato!
I've been using this knife every day in my kitchen for about a year now, and overall I'm very happy
with it! The edge retention has been fantastic, and the handle is really comfortable. There are a
few changes that I would like to make though... I think the edge could be thinned out a little bit,
and the handle could be a little fatter. I also think that food release could be better,
so I'm going to be experimenting with adding some texture onto the side of the blade.
I'm currently in the middle of designing the CNC processes to make more of this knife, so if you'd
like to be notified when it's finished make sure to sign up for the mailing list on my website!
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Thanks for watching!