Recommendation? Can’t get blade tip sharp using Hapstone

[SanFranDiver]

Just got a Hapstone R2 sharpener. Love it. Half dozen blades are sharper than ever.

However: I’ve set my blade angle to 15-18 degrees (depending on the knife). On both an 8” chef’s knife and a 14” Bowie knife I’ve found that once I start rounding the turn at the tip the stone angle seems wrong and the tip remains unsharpened.

Can’t figure out what I’m doing wrong or how to [properly] fix this “problem”.

Help? Suggestions?

 

[c7m2p3]

Typically what is happening here, especially with longer blades such as these, is the further you are getting from the clamp point (where the jaws of the clamp are interacting with the blade face) the angle becomes more steep or acute. Unfortunately this is an inherit flaw in fixed angle clamp systems. They are fantastic for maintaining angles for sharpening and getting incredibly consistent results but they are usually best used with pocket knives or things under 5inches in blade length. Even some of my folders over 3.5 inches I will start to see this near the tip.

Some ways to try and mitigate this would be to sharpen about half the blade so the first 4 inches or so on the chef's knife, and then when you have done that (I would color the edge so you know where to stop) you would unclamp the blade and move the clamp back down to the unfinished section and sharpen the remaining 4 inches.

Another way to try and do this without unclamping the blade would be to sharpen the length of the blade for as long as it seems like it is working and then when you get near the tip, very slightly increase the angle. Again; you will be served to color the edge by the tip with some sharpie (i use a red one) and see when you are hitting the edge.

 

[SanFranDiver]

Hi C7...
Thanks for the info. Just curious, what is the alternative to “fixed angle clamp systems“ - Examples? BTW, I’m a sharpening newbie.

 

[c7m2p3]

Hi C7...
Thanks for the info. Just curious, what is the alternative to “fixed angle clamp systems“ - Examples? BTW, I’m a sharpening newbie.

Well of course there is hand sharpening though that is going to have a learning curve to get a feel for angle, pressure, etc. You could try and go to a powered system like the Ken Onion Worksharp with the Blade Grinding attachment. Then there is the tried and true "crock stick" systems like the Spyderco Sharpmaker or the lansky turnbox system. These are going to be good for maintaining edges not so much for resetting the bevel.

 

[Old Biker]

Hi C7...
Thanks for the info. Just curious, what is the alternative to “fixed angle clamp systems“ - Examples? BTW, I’m a sharpening newbie.

An edge pro style table system allows you to move the blade along the table. Keeping the blade in the range where the angle is consistent. For you the easy answer would be to buy either the Hapstone V8 module, or the M3 module. Either one will fit your R2, and both should work fine with chef's knives. The M3 is less expensive. The downside of the table system is, you have to hold the knife on the table. That means that when sharpening one side of your blade, you have to learn to run the guide rod with your off hand.

Here are examples of three positions I might use with my 10 inch chef's knife.

O.B.

 

[bucketstove]

Just got a Hapstone R2 sharpener. Love it. Half dozen blades are sharper than ever.

However: I’ve set my blade angle to 15-18 degrees (depending on the knife). On both an 8” chef’s knife and a 14” Bowie knife I’ve found that once I start rounding the turn at the tip the stone angle seems wrong and the tip remains unsharpened.

Can’t figure out what I’m doing wrong or how to [properly] fix this “problem”.

Help? Suggestions?

Hi,
I think the maker goofed the instructions ... hopefully this helps

post

post

 

[fvdk]

Typically what is happening here, especially with longer blades such as these, is the further you are getting from the clamp point (where the jaws of the clamp are interacting with the blade face) the angle becomes more steep or acute. Unfortunately this is an inherit flaw in fixed angle clamp systems. They are fantastic for maintaining angles for sharpening and getting incredibly consistent results but they are usually best used with pocket knives or things under 5inches in blade length. Even some of my folders over 3.5 inches I will start to see this near the tip.

There we go again.
This has long been proven not to be the case., see: https://www.bladeforums.com/threads/angles-on-clamp-style-devices.1339022/page-2#post-15412040

There are more elaborate posts on this topic but is short, as long as you're in the straight area of the blade, the angle won't change, no matter how far down you go.

 

[c7m2p3]

There we go again.
This has long been proven not to be the case., see: https://www.bladeforums.com/threads/angles-on-clamp-style-devices.1339022/page-2#post-15412040

There are more elaborate posts on this topic but is short, as long as you're in the straight area of the blade, the angle won't change, no matter how far down you go.

I realize this comes from the Lansky literature though after reading through that thread I am open that they are just totally off base when it comes to the planar bevel angle versus the angle created by the "arm" holding the stone. That seems to make sense.

However, the end result should be the same no? As you get towards the tip its not the angle that is changing per se, but rather the belly of the knife going up toward the tip that is changing the angle and resulting in a far wider bevel.

With this in mind would the proper place to clamp a knife with a fairly significant belly be far towards the tip and then move and reclamp it toward the flat area? Effectively sharpening even sub 4 inch blades in two sections so as not to have a radical shift in bevel size?

 

[fvdk]

Placing the tip of the knife at the same distance of the pivot point as the belly of the knife and thus in the arc of rotation of the rod arm, makes the bevel angle more predictable and consistent. That being said, if the knife is thicker at the tip than it is at the belly, you will have to choose between keeping the same angle but getting a wider bevel or changing the angle and keeping the bevel the same width.