How to decide what bevel angle to use

B

Bayouforge

Joined
Nov 15, 2016
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9
Im new to knife making... ive been practicing on scrap metal and barstock for months... i have the filing technique down... and heat treating... balancing... and although ive never put a handle on one... i use to make wooden pipes so i dont for see any major issues there... but ive been beveling by eye... and now really focusing on proper angles etc... so thats where i am... my question is... im making a 16.5" (total length) bowie for a friend... what angle bevel should i use? The knife is 1/4" 5160... i was thinking a compound bevel woild probably be ideal for a heavy chopper like this... but i have no idea what angle to use or how to messure and mark it on the steel before i start... and i cant seem to find anything except vague description online... a little help would be great... i want it to have a good sharp edge capable of cutting but able to hold up to chopping a 4" tree limb...HELP
 
You may find this useful in determining the grind angle that will work for your project. Using a Bubble Jig a Bowie of that size would be right around 2 1/2 degrees for a full flat grind.
At 16.5 inches and 1/4 inch thick, this is going to be a heavy knife. Grinding distal taper into it will help lessen the weight and put the balance point closer to the front of the hand.
Good luck, Fred

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Fred.Rowe said:
You may find this useful in determining the grind angle that will work for your project. Using a Bubble Jig a Bowie of that size would be right around 2 1/2 degrees for a full flat grind.
At 16.5 inches and 1/4 inch thick, this is going to be a heavy knife. Grinding distal taper into it will help lessen the weight and put the balance point closer to the front of the hand.
Good luck, Fred

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Click to expand...

Fred your a genius!
 
valknut said:
Fred your a genius!
Click to expand...

He must be.... or im just a dumbars... that chart is greek and most of what he said was ancient hebrew haha.... pretend yoyre talking to someone who roofed houses for 20 years... and has good common sense and very little formal education... because you are haha
 
I'll be honest. I mostly choose my angle based on how I want the knife to look. So the height and the edge thickness determine the bevel angle for me.
 
From my limited understanding on this subject (and i may be off base) is im looking for a 30° bevel and a 40° sharpened edge... IF i were doing a single bevel
 
But... from what ive read... a straight bevel is more for a lighter weight knofe intended to be a cutter... thats why im trying to figure out the compound... if no one can explain it to me in layman's terms i gues ill just guess at it... i do know how to calculate a right angle so i can probably get fairly close to correct on the double bevel... :/
 
But... from what ive read... a straight bevel is more for a lighter weight knofe intended to be a cutter... thats why im trying to figure out the compound... if no one can explain it to me in layman's terms i gues ill just guess at it... i do know how to calculate a right angle so i can probably get fairly close to correct on the double bevel... :/
 
Just pick you blade thickness and the geometry shape and make it. The angle will be what it will be. The only angle that is critical is the edge angle. For a heavy chopper 30-35° inclusiove is about right.

Bayouforge:
A blade with a 30° bevel and a 40° edge would be a splitting maul.
 
Bayou, Are you needing the angle to set the jig (Bubble or mechanical)? The thickness of the blade (1/4" in your case) and how high you wish the bevel to be will determine the angle. "IF" you're building a Bowie you might not wish a full flat grind, but have the bevel up about 1/2 to 3/4 of the way to spine? How wide is the blade - 2"? 2-1/4"? Those factors will determine the angle. Say it's a 2" wide blade you wish the bevel to come about 3/4 of the way to spine which would be 1-1/2" high bevel. That would require about 4.35º on each side with leaving .020" for the edge.

I hope this helps,

Ken H>
 
I do like Karaki and figure out where I want the grind to stop by looks. I use an app on my iphone to set my platen angle based off of the thickness and height of the grind I want.

The app is called Right Angle.



I enter my known dimensions into the fields. For the base, it will be half the thickness of my steel.



Once they are in put done and it gives me the angle after clicking done.



Once it gives me the angles, I delete out the slope, and rise as they will be changing, and subtract .010" from the base so I have half the thickness I want for heat treat. Leaving in the angle and click done. Now I know what my grind height line will be for prior to heat treat. when i'm grinding I can watch this line and the edge scribed lines and I know I will have the look I want when I layed the blade out.



The new height is what I will grind to prior to heat treat. If I set my platten on the exact/close angle I meet both line at the same time.



I do all flat grinds and take my edge down very close to 0 so I'm very very very close to the exact lines of my drawing.
 
That's a neat app - I might look for that. I normally just use a calculator for

angle α = arctan (base/Height); { (arctan = tan -1) (on calculator is “shift tan)}

where: "base" equal 1/2 of blade thickness minus the amount desired for edge. i.e. if blade is .100", and you wish a .010" edge, then "base" = .100" - .010" =.045"

where: "Height" equal grind height of bevel

example. .25" blade desiring a 1.5" grind height with a .020" edge left for post HT work

(.25-.02)/2=.115; α = arctan(.115/1.5) = 4.38 degrees.

I think I covered everything - if I missed anything, somebody bring it up.

Ken H>
 
Ken H> said:
That's a neat app - I might look for that. I normally just use a calculator for

angle α = arctan (base/Height); { (arctan = tan -1) (on calculator is “shift tan)}

where: "base" equal 1/2 of blade thickness minus the amount desired for edge. i.e. if blade is .100", and you wish a .010" edge, then "base" = .100" - .010" =.045"

where: "Height" equal grind height of bevel

example. .25" blade desiring a 1.5" grind height with a .020" edge left for post HT work

(.25-.02)/2=.115; α = arctan(.115/1.5) = 4.38 degrees.

I think I covered everything - if I missed anything, somebody bring it up.

Ken H>
Click to expand...

I could have probably done that years ago. Ever since they came out with the construction master calculators that looks like cryptic code.. :D
 
Nothing to do with my question... but im sotting here looking at all of the math... this must be what metally challenged people feel like looking at physics equations... sadly i was EXTREMELY good at math in highschool... i think i did WAAAAAAAAAAYYYYY too many drugs in my partying days... haha... thanks for trying to help... atleast i know the cutting edge should be around 30° the rest i think ill just eyeball and hope for the best... for the amount of time ill have in this knife v.s. what im charging... its just not worth studying trig for a month... if they dont like the knife ill take it back and resell it
 
I should take another iq test... haha in 3rd grade i was failing all of my subjects... (refused to do the work it was boring) they gave me a placement test because the school wanted to move me back a grade or 2... it showed i was on a college reading and comprehension level and highschool graduates math level... they then made me go to a psychologist and take an iq test... i scored a 168... after all of the drugs in my young days... and how difficult im finding this to be... i have to wonder just how much i lost to drugs in my 20s... but on the bright side... i could be the new spokesman for not doing drugs.... talking about this is your brain... this is your brain on drugs bahahahahahaha
 
Fred.Rowe said:
You may find this useful in determining the grind angle that will work for your project. Using a Bubble Jig a Bowie of that size would be right around 2 1/2 degrees for a full flat grind.
At 16.5 inches and 1/4 inch thick, this is going to be a heavy knife. Grinding distal taper into it will help lessen the weight and put the balance point closer to the front of the hand.
Good luck, Fred

Top.jpg
Click to expand...

valknut said:
Fred your a genius!
Click to expand...

Fred

If you link to the original, it's readable when it's printed.

http://www.bladeforums.com/forums/attachment.php?attachmentid=100151&d=1213490448
 
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