Knife Blade Angle

[Pandabean]

Guys,

Got a quick question for you all.

I know there is a magic number for the angle of a blade and that being 22.5 degrees. Now my questions is, is this 22.5 degrees on each side of the blade or 22.5 overall?

Also what would be the easiest way to measure this?

 

[robin wood]

Guys,

Got a quick question for you all.

I know there is a magic number for the angle of a blade and that being 22.5 degrees. Now my questions is, is this 22.5 degrees on each side of the blade or 22.5 overall?

Also what would be the easiest way to measure this?

22.5 overall is a good angle for a general purpose balde, it is on the sharp side, I tend to use 25 on my woodcarving knives. A 20-22 degree primary grind with a small secondary microbevel at 25 is I think the perfect general purpose tool and is how most Scandinavian blades come when new (eg frosts mora and clipper)

The easiest way to measure it without specialist tools is with a pair of scissors, tighten the screw on the scissors so they don't flop open and closed easily. rest the bevel of your knife in the open angle of the scissors and hold them up to the window and adjust the angle until the blades of the scissors lie exactly on the two bevels of the knife. Now put the scissors on a piece of paper and draw along the two cutting edges. You can now measure the angle with a simple protractor.

 

[Pandabean]

Thank you Robin. We are nearly done with our knives and we wanted to be sure as on the Greenpete video he says he has his jig at 22.5 degrees which would give 22.5 on each side would it not? or have i misunderstood that?

Andy

 

[Hoodoo]

A cheap protractor with a swing arm will give you quick and easy measurements.

 

[robin wood]

Thank you Robin. We are nearly done with our knives and we wanted to be sure as on the Greenpete video he says he has his jig at 22.5 degrees which would give 22.5 on each side would it not? or have i misunderstood that?

Andy

Not necessarily, the jig on the Tormek grinder for instance if set at 22.5 gives you that total edge angle. The bottom line is 45 would be a very broad angle to put on a knife. As I said 25 total would be the norm, 30 if you want a very robust edge for serious rough chopping on a big blade any more just makes for more resistance as you try to cut something.

A cheap protractor with a swing arm will give you quick and easy measurements.

Nice little protractor, I want one of those.

 

[Pandabean]

Thanks all.

Has anyone got pictures of a jig so that we get an idea of how to put one together? That protractor looks quite nice.

We have something similar for measuring angles where you put the blade in between the metal and wood and then draw on the paper and measure. This came out about 30 degrees. However I also have an inclinometer from my geology course and that measures each side as abou 12-13 degrees. I would go by the inclinometer as I couldnt really get a good fit with the angle measurer.

Seems sharp enough to feather a stick & matchstick . Not managed to get a bald arm yet