Friday, March 28, 2014

Very First Blog Post! New Hook Knife

For a long time I have been using the standard Mora hook knife and have become quite accustomed to it. After watching people use the big twca cam knives, I was inspired to make my own.

What you see here is a small hand crank forge, made in PA, that we found in an antique mall displayed as a garden decoration! After some restoration and an added heat shield, this little forge has turned out absolutely great. Behind it is a 180lb Hay-Budden farrier anvil which was found at a flea market. 

Our source of steel was a leaf spring from a truck, not exactly sure of its composition but the results have been very impressive. 
After initial forging, the piece was heated once more and allowed to air cool.

During the rough grinding stage, care was taken not to make the bevel too thin (to avoid burning it in the forge). This is the single external bevel. Single and flat bevels seem to work the best for wood carving in terms of control and ease of sharpening. The back side, that will become the internal face, was slightly hollow ground to compensate for the bending stage when the inner material will compress and become convex.

At this stage the knife was heated again in the forge and bent around the horn of the anvil. I do believe that next time I will use a two inch piece of pipe to bend the knife around because the horn of the anvil does not have a circular shape. The bend turned out alright, there is a slightly flat spot in the middle, but I think it should work. Next, the knife was heated to a cherry red and quenched in some motor oil. It seemed to work as a file would skate over the surface. To temper the blade I first gave it a thorough clean and put it in the oven at 350 degrees F for 1 hour (again, not sure what is exactly in the steel but I have heard a lot of success stories using this method). 
When out of the oven the steel was a light golden hue, so I believe that the temperature was OK. I spent a little more time at the grinding wheel to thin the bevel, ensuring to keep the blade cool by dipping it in water so not as to ruin the temper. Afterwards I spent some good time on the water stones cleaning up the free-hand ground bevel. The single flat bevel was very easy to run along the stones.

Here I have put a handle on it and wedged in in firmly. I am extremely impressed at how well this little hook knife works (already a blood stain near the bottom, this thing is sharp!) I wanted to make the large twca cam style, but the piece of steel I used was not quite large enough. Nevertheless, the extra handle length can give you some good torque to hollow out a spoon blank in no time! So far I have hollowed a few spoons and the knife can still shave the hair on my arm, I believe hardening and tempering was a success! 
I hope you enjoyed seeing the birth of my new hook knife. I plan to make another soon, this time a larger twca cam style with a big handle.