Thursday, September 17, 2015

KN18 KITCHEN UTILITY KNIFE - INITIAL LAYOUT

I am working this knife from some AEB-L 3/32" stock. I guess it's probably 2.4 mm or something like that as it's made in Sweden.  The length piece is 12" x 1.5" The pattern is a KN18 full tang.
Here I am rough grinding the primary bevel with a 60 grit ceramic belt (that's looking like it's seen better days!)
Some of the tapering I like to do on the 4 x 36".
This is the basic shape of the knife. It's quite appealing.
Now I mark and drill the holes for the pins in the tang. There are three holes for the scales to go in with and two forward holes for the bolster.
Finished drilling the tang holes.








After I drill the holes for pins I drill a bunch more random holes to take some steel and therefor weight out of the handle.


KN18 KITCHEN UTILITY KNIFE - HEAT TREATMENT

Once the grind is down to about 0.05", I brush some protection on and got the oven warming up. After soaking for about 15 minutes at 1060°F (1940°F)
This is what she looks like out of the oven. I goes from bright yellow to red pretty quickly. As this is air hardened steel, this is getting hard just looking at it.
I slip it between to copper plates for a rapid cool.
Here I am checking for warping. Looks good!
Almost immediately I have it in the tempering at 185°C (365°F). Two full cycles of two hours is good for tempering.
This is what it looks like out of the tempering oven. Some scrub with a pad will clean off the protective paint, but I have final grinding to do so not worrying about being so clean right now.

KN18 KITCHEN UTILITY KNIFE - GRIND

After tempering I am back at the grinder to bring the blade to final dimensions. I am trying a technique that I saw on a flat grinding video where the oldtimer always flat grinds from the same side of the grinder. I am using a 60 grit belt here.
The technique seems to work okay. I gauge the angle by how far the spine is away from the belt, say 1/8".
I've ground down to close to 20 thousandths. Enough to work the final cutting edge from there.
Some light scratch removal with a 120 grit.
And hand sanding up to 400. Once in 400, I draw the paper across the blade only in strokes one direction.

KN18 KITCHEN UTILITY KNIFE - S.S. BOLSTER

I want to add a stainless steel bolster to this knife. I have done some basic layout and added a small arc to the rear of the bolster. This should look pretty sweet.
I have some 304 stainless stock and I trace the shape for the left and rightside pieces.
Now to cut out on the band saw,
Once cut I clamp the two pieces together and shape them to the line as a single piece.
While clamping one piece I drill through from the tang.  Holes are for 1/8" stainless pin stock.
I put a temporary pin in and drill the second hole. This process of adding a temporary pin and drilling repeats until all four holes are drilled and the edges line up perfectly.
Removed from the tang, I force the pieces toegher and pin.
Now the bolster can be shaped as a single piece.
Here I am getting ready to press the pins in.
I clean everything very well with acetone and press the pins with some spacers and washers. This make the bolster pieces compress to the tang before the pins grab.
A shot on the grinder and the pins have disappeared.

KN18 KITCHEN UTILITY KNIFE - HANDLE

For the handle I have some lacewood scales. I the fleck patterns in the wood. I arced the fronts to match the arc in the bolster pieces.
For matching the curves I used the disc sander and then went carefully with some 220 grit sandpaper and a wooden block until the match was very close. A gap here would look bad, so taking the time really shows.
Once shaped, I clamped and drilled out the holes for the pins.
Repeat the drilling process for the left scale.
Here I have roughed out the shape on the band saw and dimpled the areas in the middles. This will increase surface area for the epoxy to hold on to. If you use this technique, be sure that your dimples are well inside the final edges or they will appears as gaps between the tang and scale.
Getting ready for the glue up. Trusty Acraglas is recommended for anything used on the kitchen. I mixed up 5 ml (1 tablespoon). Note the black vulcanized spacers that go between the scale and bolster pieces.
Here we've clamped up and made sure that enough epoxy squeezed out in all directions. This will fill any microscopic voids.
After a day of hardening this is the handle. Looks like crap right now I know, but a few minutes on the grinder and it will be looking like a real handle.
Faces are flatted.
Adding some roundness.
Working the curves a bit more. Here I am working with sections of sand paper and hand sanding. As the wood is softer than the metals, I am being careful not to hollow the transitions from the wood to the harder materials, pins and bolster.
Now a dip into the wood stain to bring out the lace effect.
Another dunk in the ebony stain to darken the wood.

KN18 KITCHEN UTILITY KNIFE - FINISHING UP

The handle is finished with several coats of tung oil. The effect of the stain really helps contrast the wood and steel.
Now I will apply my maker's mark by electroetching with a stencil.
After the etch I like to buff the area around the mark with a very fine non-scratching blue Scotch-Brite pad.

I also etched the type of steel used, AEB-L.







I cut the edge at 17° on the belt grinder and sharpened water stones. This is a slicer!