Tips on tips

MBB

MBB

Joined
Apr 18, 2014
Messages
244
Any tips on not making the knife tip too fragile during grinding? It's one of those hurtles that plagues me at this stage of learning. I'm working on a kitchen utility knife and have bent the tip once and accidentally hand sanded it off twice. It's flat ground at 2.5 degrees 2" wide AEB-L at ~63 HRC.

Thanks!

Mike

https://imgur.com/gallery/2125yMz
 
In my experience free hand grinding, makers tend to lessen the bevel angle as they move towards the tip. This will in turn make the tip quite thin. If you are using a jig, that could help maintain the angle, but other factors still come into play. For example: does your chef knives have distal taper? If so, then that taper will require that you change the bevel angle as you move towards to the tip to keep the grind lines parallel to the edge. There are ways to be mindful of those issues and grind a stout tip. But that takes practice and playing around with grinding techniques.

The easier answer is to make your profile a bit longer than final shape. Put the bevels in and then grind back the tip to thicker cross sections. This is an easier work around... If I am doing a new design or trying new techniques, I will first profile the blade to be 1/2in longer than final shape and then go from there... If I don't have to grind back the tip, then the customer ends up with an extra 1/2in of blade, which never seems to be an issue.
 
I leave some meat behind the tip (it isn't a point yet) until it's about how I want it, then I finish the profile to remove that extra meat. This makes it grind slower and it reduces faceting.
 
when you are in final finishing and cutting in the sharpening bevels ( i do this by hand on stones) you can just leave exactly how much of a tip you need. If you lose the pointyness then just take the "belly" of the spine down until a new point is formed.
 
the closer you get to the tip, use less pressure against the belt. i also kinda try to avoid the very tip until i get to 120 grit.
 
I was using the approach of taking the spine down towards the bevel, but the closer I took it, the less "meat" I had to work with leading to fragility. I had left the tip thicker than the belly of the blade pre-heat treatment in order to avoid this problem, but then found myself having to aggressively work to even up the grind at the tip during final bevel grinding.

So should I increase my grind angle at the tip and then merge that bevel into the rest of the grind afterwards?
 
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