Tuesday, August 11, 2020

Ulu

 


The Ulu is the traditional knife used by the people(s) in the Arctic. The cutting blade was originally slate rather than steel. Since slate is not all that strong in tension, the design stressed the slate in compression by putting the handle directly above the cutting edge.
 
That has some significant ergonomic advantages and the broadly curved cutting edge is the cat's meow for skinning.

I decided I was going to make my own Ulu.



Anything worth doing is worth doing to excess.
 
The saw blade cost about $10 new and there is enough material in it to make five ulus with a 6" cutting edge.

The red slots are how I intend to attach the tang and then the handle. I can grind a slot in hardened steel. I don't have the equipment to drill a hole.

Material
With a little bit of experience it is possible to estimate the amount of carbon in steel based on the sparks.

Low carbon steel throws sparks that don't explode. Medium-low carbon steel throws a spark that has a very modest "poof" at the end. Medium carbon steel has a more vigorous "POOF". The plume of sparks for high carbon steel looks like a fox tail, it is so broad and bushy.

I was surprised that the sparks from this saw blade looked like my mental picture of medium-low carbon steel. I suspect this steel gets most of its mechanical properties from 0.20%-to-0.30% carbon and the cold-rolling and not from heat treating. Well, they gotta make it cheap if they are going to sell it cheap. It should be OK as long as I don't overheat the edge while grinding.

To be continued...

Bonus picture
The grapes are starting to color up.

We ate a honeydew melon yesterday.

We have been eating sweet corn from the garden although it is not really ripe, yet.

We are getting buried in tomatoes. I expect to be canning them tomorrow.

4 comments:

  1. I wonder if there is some metallurgical alchemy going on that makes the teeth hard, but the rest of the blade is softer and less prone to breaking?

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    Replies
    1. I readily see that on the blades for bow-saws. The teeth are darker where they are flame or induction hardened. The darkness is caused by an oxide film.

      If you know any carpenters you can probably get all the saw blades you want, although most of them will be 7-1/4" diameter. If you are getting them for free then there is no reason to try to squeeze as many knife blades per saw blade.

      I opted to buy a "plywood blade". It has small teeth which minimizes waste and the amount of grinding needed and $10 is within the ERJ blog budget.

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    2. Good thinking on optimizing what you get from the blade, and I did spend a little internet time trying to find out what blades would be good candidates for knife making.
      As always the answers weren't in agreement. More research is needed.

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  2. Gave my MIL an ulu from when we lived in Alaska. She loved it.

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