How would you flat grind this blade?

Will Batayte

Will Batayte

Joined
Jan 8, 2007
Messages
640
Ok so here's the first real design that I've actually wanted to do and isn't just a simple practice blade. But when thinking about the grind I'm worried as I flat grind it I will soften out the transition between the two blade profiles. I don't want this at all. This is a legal carry kali/escrima technique inspired fighter and I want that hook nice and sharp. But I feel like if I keep the grind line nice and flat the added thickness in that area will cause the secondary tip to start to dissapear. I also desided to leave off the thumb ramp.


Aparently no matter what I do there's a problem between my photobucket app and my tapatalk app so my image keeps posting as a broken link. I will try to straighten it out asap. For the time being the blade type im describing is an extremely deep bellyed recurve bowie with a sharp transition between the hooked portion and the normal bowie upswept tip. The blade is 4" long and 2.5 inches thick at the tip of the recurve then hooks down to aproximately 1.5" at the start of the guard. Think of a more extreme version of a tracker knife but replace the the big clunky tip with a very sharp clipped bowie tip.
 
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Its odd whats going on. I usually use the photobucket app to upload my pics then I tend to post with tapatalk. But for some reason this time its not working. Not sure how else to get it directly in the post
 
I use plywood to prototype my designs and get the ergos right. I can make 10 generations of plywood protos in the time it'd take to cut one steel blank. As you can see in the proto there is a thumb ramp. I liked the look and feel of the blank without it so I decided to leave it off. But I will be making both versions. The thumb ramp becomes a useable aid in hooking and trapping the wrist of the opponent when the blade is held in reverse grip
 


There you go. I don't know anything about grinding a blade of this profile. It looks like it may end up tantoish.

It may would help to explain or draw where you want the cutting edges to be, and someone can help with grinding technique.
 
What are you using to grind? If you are using some kind of belt grinder , you might want to use a slack belt set up. Use high tension and a light touch on your passes to keep the bevel as flat as possible. Depending on how large the blade is you might need to use a 1" wide belt to grind the recurve portion of the blade.
 
I'm curious how thick will it be? I gotta say it's a unique design and I think it will be a tricky flat grind.

Corey "synthesist" Gimbel
 
Yikes! That'll be a tough one. I'd think you'd have to do it as two seperate edges. Do the main curved section first, then do the tip section. Pretty much like a tanto. That would be my thought. Maybe make a few extra wood blanks and try a few different methods with a 50 grit belt before you try on the metal.
 
Can't help with the knife part. In the last big PB update they removed the tags from the tap to copy links. Not sure if that's the problem you are having, but I got tired of all of the new bugs. Downloaded the Imgur app and haven't looked back. Works well with tapatalk. I'm not sure how my pics come across on a computer monitor, but Imgur is waaay faster to upload so I'm guessing there is a discrepancy between PB and Imgur, either pic size or resolution.

Check your PB forum link to see if it includes the necessary tags. If not, you can still use the PB link by using the tapatalk insert image tab, then pasting the link into the provided [IMG] tags.

Hope that helps.
 
I can't even tell what parts of that thing are supposed to be sharpened. Just exactly what is it to be used for?
 
Ok I've drawn up different grind profiles to explain what I want to do and what I don't want. I'm attaching a link to my drawings. Im using a variable speed kmg 8. I have a bubble jig, but I'm still very new to this. I know at this point I should be making simple drop point knives but I have had this design in my head for a long time. I'm a modern arnis practitioner and it's desgined to be used defensively with the tecniques from modern arnis and other filipino martial arts. Its basically combining the hook of a karambit with the belly, tip and clip of a bowie. Because I'm a beginner and my limited experience has been with flat grinding so if you look in my drawings I want to do early models with just a simple flat grind like the first drawing on the left. Then add in a fully sharpened clip on the bowie section. For use with backcuts. The two drawings show what looks like a tanto grind are what I know would work to solve the problem but I don't want to do because I'm just not a fan of the look of it.
http://s683.photobucket.com/user/coldblooded357/media/20140224_104934.jpg.html?sort=3&o=0
 
This photo will give you an idea of the size of the blade and you can see where the edge and point are in relation to the hand. And hopefully get a feel for how effective this design would be in a self defense situation. I also went extra wide on the blade because in most places 4" length is the limit. They don't limit the width. Wider knife wider wound, quicker stop to the attack. Is like a .45 instead of a .22. http://s683.photobucket.com/user/coldblooded357/media/20140220_150933.jpg.html?sort=3&o=2
 
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