Intro and Trouble Shooting

[Matty S]

Greetings from Wisconsin. I'm hoping I can get some help with a dilemma I'm facing. I've made a couple of knives and enjoy the process, but now friends and family want knives. I'm wondering if there is a way to lay out a knife if you are not going to be grinding with a jig that can help determine the angle?? I do a bit of carving and wood working and prefer a scandi grind ( it's an easy grind for me to understand coming from the world of bench chisels and plane blades). I grind my blades free hand on a belt sander because that's all I have at the moment.? If I want to do a scandi grind free hand how do I know what my angles are? It's not a big deal when I am making a knife for myself (if I don't like how things turn out I can change it down the road after I've carved with it a while) but if I am making a knife for someone else it has to be right the first time.



Any help would be appreciated. Thanks
Matty

 

[Boogaloo]

Trigonometry is your friend. If you know your stock thickness subtract your edge thickness (if doing secondary micro bevel) divide this by 2 to get the short side of your right triangle.
The length of the grind gives you the hypotenuse.
Inverse sine of the short side/hypotenuse gives you your bevel angle (per side of course).

 

[i4Marc]

You need a sine table. Here is one from Travis Wuertz's Facebook page:




And here's one from another poster a while back:

 

[Stacy E. Apelt - Bladesmith]

I say it often, but I'll say it again :
You don't need to know or try to achieve any specific angle on a scandi when doing the bevel. You just make it and it is what it is. A scandi has a pretty acute edge angle anyway.

Setting a jig at a specific angle when grinding/sharpening a chisel or planer blade is all done on one geometric plane. The angle never varies from one corner to the other and the edge is a perfect straight line. However, knife blades have tapers and curved edges.Trying to keep to an exact angle at the edge will make the grind not follow the profile the way you want on a scandi. Grinding the bevel so it rises to a pre-determined line will get you a proper looking Scandi . The actual angle will diminish as it goes toward the tip.


If you just have to know the general angle so you can sleep at night, a chart or a simple trigonometric calculator will tell you. Here are the normal general angles of Scandi blades.
If the blade is 1" wide and made from 1/8" stock, and the grind goes half way up the side ... the edge is a 14° angle.
Take the grind 3/4 the way up and it is a 10° angle.
Go FFG and it becomes a super sharp 7°.
Those are the actual (included) edge angles.

Personal rant: I never understood why knife people give specifications in the "per side" format, as that only would apply to setting a jig or grinding machine. Once finished, the edge is only one angle, not two separate sides. You don't buy beer in a can filled with two six ounces, do you.

The point I'm making is you really don't care what the angle is. Since there is no secondary edge angle, it is going to be whatever it is. If you want a more robust hunting scandi, make a shorter bevel. For a soft wood whittler, go higher up the side. For a scary sharp slicer, go FFG.

Personally, I put a tiny micro-bevel secondary on my Scandi grinds. It isn't a true Scandi anymore, but it will last longer and be far easier to resharpen.