Brisa Nessmuk edge problem, help/advice please

[moley1508]

hi all,

I have made a Brisa Nessmuk kit the steel is 80 CrV2 (HRC 58-59)

I have re-profiledthe edge to a true Scandi and therefore removed the secondary bevel.

I cam home tonight to find that my Mrs kindly placed the knife in a plastic bag with some wet sharpening stones unbeknown to me. you can imagine what happened. rust.

so now I have a fully stripped version and have re done the edge.or so I thought.

so the edge felt very sharp to the touch but I could feel a burr so some stropping was in order.

this straightened out said burr and it went through printer paper just fine. for about 3 cuts and then the blade started catching and the burr re-appeared. stropping sorted it again but the same issue occurred after.

how can I get rid of the burr, I don't like secondary bevels. is the steel at fault? (I ask as this is the second Nessmuk from Brisa I have had, the first had QC issues but Brisa were brilliant and sent a replacement)

love the knife but am concerned the heat treat may be an issue.

I would very much welcome some advice form anyone who is more knowledgable than I on this topic.

thanks in advance,

Money.

 

[Bionic]

How did you move the blade over the stones? Did you mimic a slicing action across the stone or draw the blade backwards over it? I’m guessing probably the latter, in my experience this can cause a very thin flaky burr that you can push out of line with mild finger pressure (very sharp but soon breaks off and hence becomes blunt) which stropping doesn’t shift. If I use that technique (which is rare for the above reason) I’ve found slicing gently in to a soft wood before stropping seems to help. To be honest I get much better results pushing the blade forwards over the stone until stropping.

 

[Janne]

Wine bottle corks are excellent in removing the semi loose burr.

Does this happen in exsctly the same place?

 

[moley1508]

Blade was pushed forwards only

Seems to be same area

 

[Janne]

I know you willingly removed the secondary bevel, but what if you create one again just to test if a larger angle of the edge solves this problem?

 

[Robson Valley]

>Ramming the fresh edge into the abrasive won't help. Pull strokes only.
>Paint the bevel with black felt marker and examine with a 10X magnifier under a very bright light.
That way, you can follow exactly what you do.
>Bevel angle: Can you hold one over many sharpenings? Machine jig or freehand?
I'd suggest a total included bevel angle of 25 degrees , not as much as 30.
>Abrasives: How fine do you go before honing on a strop? 1,500 grit is plenty.

 

[moley1508]

thanks guys.

my freehand sharpening 'skills' haven't let me down recently with my moras or when putting convex edges on my beckers or sharpening an A1.

Robson, what do you mean by 'ramming' please as I am not sure and do you mean I should sharpen only by pulling the edge along a stone as you would when stropping?

I run up to 3000 but the stones seem very soft to me and more like 1500-2000

thanks for the advice so far

 

[C_Claycomb]

I think that RobsonValley is disparaging the method of sharpening where one "takes slices off the stone", moving the blade towards the edge, rather than away from the edge, as one does when sharpening with abrasive paper or when stropping.

When trying to control the burr, moving the blade towards the edge does help. One just needs to think through what is happening at the edge and it is obvious. It doesn't matter whether you are filing, grinding or honing, burrs form much more readily and often on the trailing edge.

What are you stropping on and how are you stropping? It sounds like you are not removing the burr completely, maybe the angle means that you are not hitting that part of the edge with the strop?

RobsonValley's suggestions of black marker pen and magnification are excellent.

Going to 1000g at the main angle then doing one or two swipes at a slightly steeper angle (main bevel 13-14deg and then last two at 15deg) so small a micro bevel that you can barely see it might help.

 

[moley1508]

Thanks. I will work on it when home later.

 

[brancho]

Youre real problem is removing the secondary bevel it is designed to have one for the strength of the edge

 

[Janne]

I always put a secondary bevel so the edge has a higher angle, on all my knives that come without one. I find the thin edge breaks to easily. The higher angle edge does not feel as sharp, but it lasts for longer and I do not need a hyper sharp edge.
This on my knives I use outside the house.

Sharpness in overhyped imo.

 

[moley1508]

so, sharpened back to 1000 and put a small secondary bevel. not as sharp but no rolling in sight.

thanks for the help and advice, much appreciated

 

[Janne]

Carve some wood and see if the problem happens again in the same place. If the steel is OK nothing will happen.

 

[Janne]

Remember, the only time you need a knife to be sharpened and honed so perfectly that you can cut a thin paper into lots of narrow strips is if cutting a thin paper into lots of narrow strips is your hobby.

 

[Joe tahkahikew]

I was wondering just like Janne, what do you use this knife for? Most time knifes and axes get bit of rust when wet, and knives & cutting tools get chipped when working. Thats what happens when you use tools. But they still work just as good without worrying too much.

 

[Lore]

Remember, the only time you need a knife to be sharpened and honed so perfectly that you can cut a thin paper into lots of narrow strips is if cutting a thin paper into lots of narrow strips is your hobby.

Agree with this. (Janne do you mind if I use this quote elsewhere ? it says a lot.)

 

[Janne]

Use away!

I suspect most blade manufacturers and makers design the edge ( thickness and angles) with the intended use, steel type, and hardness in mind.

To increase the angle ( = thicker ) will improve the longevity and strength and can be done. To do the opposite is maybe not a goid idea.

We learn as long as we live!

 

[brancho]

We learn as long as we live!

Thats what we should do but not enough do. If you make big enough mistakes it is not always possible for you to learn from them.

 

[robevs73]

I'd resharpen it completely.