Micro-bevel question

[bladeprince]

What is the purpose of a micro-bevel? Also, is a micro-bevel always a wider angle than the sharpened main angle? For example, if my main sharpened angle is 30 degrees, would the micro-bevel be 40 degrees? I have 4 knives I have taken the time to change to a 30 degree angle. I have found that it is a lot of work doing this to an S30V blade on a Sharpmaker. It seems most, if not all, knives come from the factory with a 40 degree angle.

Also, if my main sharpened angle is 40 degrees would I even bother with a micro-bevel or would I put on a 30 degree micro-bevel (a lesser angle)? If a micro-bevel is always a wider angle, it doesn't seem to make sense to put on a 50 or 60 degree micro-bevel. I could even do it with the sharpener I have.

I'm confused about this, it's purpose and if it really even does anything to add to the blades sharpness or the help keep is sharp longer.

And one non-micro-bevel question. Does it make sense to take a knife that I have reprofiled to 30 degrees, and then take a few draws on the 40 degree angle to "grind" off some of the "shoulder"?

Regards and thank you to the experts,
Gary

 

[gud4u]

What most would like in blade performance is the best combination of:
- Slicing performance.
- Edge strength.

We can always improve slicing efficiency by simply honing the edge bevels to something like 10 degrees per side (20 degrees included angle) - but the thinner edge may result in insufficient edge strength when cutting harder material - the edge chips or bends when cutting harder materials.

Edge strength is just what it sounds like - strength at the edge. We can strengthen the edge by adding two very small bevels right at the edge. We now have 'compound bevels', consisting of:
- Two main bevels of 10 degrees each.
- Two added bevels of 15 to 20 degrees each, whatever is needed to strengthen the edge for cutting harder materials.

Micro-bevels:
- Require very little steel removal.
- Are much easier to maintain than full bevels.
- Strengthen the edge.
- Have very little effect on apparent sharpness.

Bevel-width of a micro-bevel is typically 1/64" to 1/32". Most would re-hone the main bevels if the width of the micro-bevel grew to 1/16".

To improve edge strength by applying micro-bevels, edge strength is improved by more-obtuse micro-bevel angles - not by increasing bevel width.

Just as an example, most of my folders are 'tuned' for slicing materials up to hardwoods with:
- Main bevels of 10 degrees each.
- Micro-bevels of 15 degrees each.

Hope this helps!

 

[STR]

It strengthens the edge actually. On some steels in particular it is the best way to keep from chipping the edge on it particularly when it is 15 degrees or so. I do a micro bevel on all my wood carving knives of the Japanese blue and white steels to help keep chipping from occurring with those super hard 64 Rockwell blades.

STR

 

[Cliff Stamp]

Very nice post.

We can always improve slicing efficiency by simply honing the edge bevels to something like 10 degrees per side (20 degrees included angle) - but the thinner edge may result in insufficient edge strength when cutting harder material - the edge chips or bends when cutting harder materials.

In general, due to the way that forces load an edge and how the forces decrease back from the edge, the very edge angle will always have to be much more obtuse in angle than the steel right behind it. Thus even if the blade was stable at ten degrees without a micro-bevel, it would suggest that it would stable with a 5 degree primary and a ten degree micro.

-Cliff

 

[duck!]

Edge strength is just what it sounds like - strength at the edge. We can strengthen the edge by adding two very small bevels right at the edge. We now have 'compound bevels', consisting of:
- Two main bevels of 10 degrees each.
- Two added bevels of 15 to 20 degrees each, whatever is needed to strengthen the edge for cutting harder materials.

Sharpmaker instructions say you should use a 40 degree back-bevel and then sharpen at 30 degrees. Are you saying that you would add a 40 degree "micro bevel" after that or are you disagreeing with the advice from Spyderco. I guess I'm confused about the definitions of "back bevel" vs "micro bevel".

 

[cbwx34]

You may want to double check your Sharpmaker instructions, you have it backwards. Page 6 of the booklet I have shows the back-bevel is 30 deg. then sharpen at 40.

cbw

 

[duck!]

You may want to double check your Sharpmaker instructions, you have it backwards. Page 6 of the booklet I have shows the back-bevel is 30 deg. then sharpen at 40.
cbw

You are right, thanks. I've actually been sharpening my knives correctly.... just transposed the numbers.

 

[bladeprince]

It also says to only use the back-bevel technique if the desired results are not met by performing the previous steps (simple sharpening). Do others agree with this? It looks to me that if one did a back-bevel anyway, that the knife would be a better slicer since some of the shoulder material is taken off. Yes, no?

And......if one re-profiles to 30 degrees, I don't think I can do a back-bevel with a Sharpmaker, unless I'm missing something. I guess I could place the rods horizontally (like on page 16 or 17) but it would be tricky to hold the blade at the correct angle. Even placing a protractor at the back for reference, it wouldn't be as accurate as I would like.

Thanks much

 

[Cliff Stamp]

It looks to me that if one did a back-bevel anyway, that the knife would be a better slicer since some of the shoulder material is taken off. Yes, no?

Yes, the concern with manufacturers is preventing damage and if the knives are used roughly you will see more damage at 15 degrees.

And......if one re-profiles to 30 degrees, I don't think I can do a back-bevel with a Sharpmaker, unless I'm missing something.

Yes, you can tilt the Sharpmaker, but for relief grinds you can just do it by eye, it doesn't need to be exactly 10 degrees or whatever.

-Cliff

 

[bladeprince]

Yes, the concern with manufacturers is preventing damage and if the knives are used roughly you will see more damage at 15 degrees.



Yes, you can tilt the Sharpmaker, but for relief grinds you can just do it by eye, it doesn't need to be exactly 10 degrees or whatever.

-Cliff

I don't know you Cliff, but your knowledge of knives and steel is always due a large thank you...so, thank you....to everyone.