Wednesday, June 4, 2014

KN7 - 8" CHEF'S KNIFE INITIAL SHAPING

With the positive feedback and suggestions received on the KN5 I 'd like to make another kitchen knife. Fortunately, I have had two requests to make chef's knives. Both would like a slightly larger blade and a handle more suited to larger hands, so I took the KN5 pattern and modified it a bit.

The new knife ends up being 12-1/2" overall with an 8" blade. The blade is 1-7/8" deep. I can allow a little more belly on the blade as I have some 2" stock to start with.





 
The two knives will come from a single 24"x 2" piece of AEB-L 0.130".






Here you can see the overlap. I oriented one blade upside down with respect to the other so I could gain the extra 1/2" per knife and still get them on a 24" piece.







Getting the profile done on the belt grinder with a Norton Blaze 60 grit and some leather work gloves.
Here are the two blanks waiting to have the primary bevels ground and holes drilled for handle pieces.







Here I am marking where the plunge line is going to be. I used a square against the spine of the blade.







Here are the twins with the primary bevels done. I used first a 60 and then a 120 grit belt.












Tuesday, June 3, 2014

KN7 - CHEF'S KNIFE PRE-HEAT TREAMENT WORK

To get from a roughly ground blank into something that is ready for heat treating takes some elbow grease.


With the blade shaped out and primary bevels roughed, it's time to start working on the blade with the block and paper. Here I used some 100 grit paper and window cleaner as lubricant.






After some time, (well I'll be honest it was a few hours) and four full sheets of sand paper, I was happy with the results.






I marked and punched the holes "free style" as there are some small variations between the two in the bolster shapes.





 
My little cobalt bit set makes quick work of the holes. Just remember to go as slow as possible. Speed=heat: which kills bits. After drilling, I deburr the holes by lightly pressing and rotating an oversized bit. This will aid in getting the pins in later. 





Here they are ready for heat treatment.
















CHANGE ALERT!


On the advice of Ray Rogers, I made some alterations to the full length bolster. The reason is after sharpening a few dozen times the blade will become shallower. The bolster will remain the same height and prevent the blade from contacting the cutting board fully.

 
















The new shape looks like the this. Now the bolster will come about 3/4 of the way down and the blade can be sharpened for years before the bolster becomes an issue. Thanks Ray!
shallow bolster on chef's knife pair

Monday, June 2, 2014

KN7 CHEF'S KNIVES - BOLSTER WORK


For the bolsters I am using 304 stainless steel that is 1/4" thick and 1-1/2" wide. I marked off  four 1-3/4" sections with a square and sharpie, then cut on the band saw.
Once I trued two matching faces, I carefully lined up the piece with the plunge line, allowing about 1/32" overhang so I could shape it back to the plunge line. Then clamped with vise-grips.
I drilled the pin holes from the tang side through the bolster piece. Add a little oil or cutting fluid here. For 304 SS, I would recommend cobalt bits. #30 bit is ideal for this.
You can see how stringy the 304 is. A super sharp bit will do this.
Once drilled, I pinned the first side with some 1/8" steel rod as temporary pins. I marked the material to be removed under the handle belly.

I then fitted the second  (un-drilled) bolster piece and clamped so that it lines up with the drilled one. Then removed the first piece.
Drilling the second bolster piece and mark the for material removal.
Now I have the two halves. I work the pieces individually on the belt grinder.
It's fairly quick, but hot work with a ceramic belt. I was wearing leather gloves and kept going back to the water pot frequently.
These are the two pieces side-by-side.

A quick test fitting on the knife.
Again pinned together, I go ahead and mark for the angled joint to scales. More shaping on the belt grinder and some special focus on the bolster fronts.
I will work up in belts on the fronts of the bolster pieces together. The rest of the shaping will come with the bolster pinned to the knife where I can match them to the handle shape.






After some work on the Norax belt.














This is the bolster re-pinned for shaping the belly. I've protected the blade in case it get dropped or hit with a belt.

Sunday, June 1, 2014

KN7 - CHEF'S KNIFE HEAT TREATMENT

I was down for a while as I replaced the elements in my oven. The results were amazing and I was able to heat treat three knives in just over two hours.

 For the wrap I use the 318 stainless foil and add a tiny piece of tissue paper.
 I crimp the edges in the carpenter's vise. Two folds are crimped.
Once the oven is up to temp I pop the first knife in spine down and tip first into the chamber.
After a 15 minute soak, I pull it out and press the knife and foil between two copper plates. With the air compressor, I blow air over the whole thing until it's cool enough to handle. 







Now into the tempering oven at 180°C (356°F) which should produce a Rockwell C hardness of 58.

Two hours then cool. Then repeat for another two hour cycle.