How to remove a really stubborn burr?

[Ratbag]

Here's a query which, in my case, relates to sharpening an Enzo D2 blade and also my Fallkniven F1 and H1:

I use a DC3 and/or a Hoodoo hone to sharpen the blades, then a belt or Starkie sharp with the blue honing paste to strop. This way I can get the blade to shaving-sharp. At this stage, one of my tests is to run the edge of my fingernail gently down the blade to detect any roughness. Usually I'm happy when the blade is sharp and smooth-feeling.

However, I've noticed though that as soon as I use the blade for wood, it immediately feels rough to the finger-nail test and I can see flat spots on the edge. I can often strop it back into shape just using the palm of my hand.

My conclusion is that these blades in particular are developing a really stubborn burr which feels sharp but then just rolls as soon as it is put to work. Other than stropping for longer, (how much longer!?) does anyone have any suggestions as to how to remove the burr?

Thanks for any comments

Rat

 

[robin wood]

My suspicion is that you edge angle is too shallow for woodcarving and you are experiencing "edge roll". This is where a section of the blade edge buckles to one side or the other when put under pressure, you can see it easily if you get a light reflecting off the edge. It is not a question of not having removed the burr.

Typically this would happen on blades sharpened around 20 degrees or so for woodcarving you need 25 degrees. Try measuring the angle of the edge using a pair of scissors resting against the bevel, transfer this to a piece of paper, draw along the scissor edge then measure the angle with a protractor.

I am not familiar with the blades you mention of the DC3 so you may get better advice from folk who know them.

Many blades are supplied with a 20 degree primary grind and a small secondary at 25-30, many people remove this secondary and then experience edge roll. Solutions would be either put a 25-30 secondary back on or if you want a zero ground blade you need to regrind the primary bevel to 25 which is a big and skilled job.

 

[Shinken]

Hi,

have you reground the H1? if not the edge is plenty thick enough not to experience edge roll, so it maybe a burr forming.

Do you move your DC3 sharpening stone towards the spine of the blade or away? and have you tried polishing paste on your strop?

 

[Ratbag]

Robin, Shinken

Thanks for your comments.

The H1 and F1 are renowned for being thick, sturdy grinds (and I have not reground them), and the Enzo has a convexed secondary bevel. I could be wrong, but I don't think any of them are ground too thin. I think it is the burr, rather than the edge proper, which is rolling.

I sharpen with the stone or Hoodoo hone in a spine-to-edge movement (otherwise it cuts the Hoodoo hone up!) and I am using blue stropping paste. Sounds like I just need to strop more?

Rat

 

[Shinken]

The spine to edge motion pushes the steel towards the edge forming a burr, polish on the hoodoo hone the other way just use really light pressure then strop

 

[Warrigal]

Your edge is to fine for wood work. Try lifting the back of the blade higher when stropping.
it will take longer to work the burrs off, and won't "feel" as sharp. But what do yer wanna do?
Fine edge for slicing, thicker edge for heavier work. Itis pretty basic really.
Carl

 

[Ratbag]

The spine to edge motion pushes the steel towards the edge forming a burr, polish on the hoodoo hone the other way just use really light pressure then strop

Shinken

I'll give this a try, thanks for the tip.

Rat

 

[Shinken]

Let us know how you get on!

If the edge is as falkniven standard then its definitely thick enough.

 

[Hoodoo]

A couple things. I would draw that wire edge out to really thin by using ultra fine sandpaper, maybe up to 2000 grit. Then instead of stropping it on a flat strop, try a mousepad backed strop. This will put more pressure on the burr without completely bending it over, so you can lever it off. Raising the edge angle on the flat strop will do the same thing but if you have not drawn the edge out thin enough with fine paper or stones, it can be tenacious. Also, a very light pass on fine crocksticks set at a greater bevel will help peel the burr off. I would still strop it after that.

 

[Nelis]

Hi,

Fallkniven knives are originally sharpened in a convex grind, to restore this, use sandingpaper (as fine as you can get, i.e. grid 1200). Place this on a soft type mousepad, and scharpen the knive with a dragging rolling spine to edge motion. This way you will sharpen the knive convex, if don correctly there is no need to strop the knive, just make sure to roll the edge far enough.

DO NOT Drag the knive along it's edge, but from the spine to the edge, increasing the angle between the edge and the paper simultaniously.

Your knive should become razor sharp.