Sharp maker/Secondary bevel question

[cchu518]

I usually go for a single bevel 20 dps, whether it's the sharp maker or turnbox.

Question for the purposes of cutting cardboard boxes anyone know if there is an advantage or disadvantages to putting a secondary bevel on knives and does blade steel matter when it comes to secondary bevels?

 

[Fred.Rowe]

Blade steel always matters in that its hardness and toughness affect how it cuts. More important is edge geometry and that means micro bevels as well.
Think of it this way: if you have an edge thats taken to zero at a given angle, in your case 20 dps or 40 inclusive. If it has been taken to zero at this angle and then you change that angle by a degree or two, the sum in your situation being 42 degrees [a micro bevel is always larger] The blade will cut less well, its more blunt, the last angle applied to the edge is more obtuse, making the cross section more blunt, meaning less cutting ability. IMHO, what happens when a micro bevel is applied, assuming the original edge was taken to zero, is a less functional [edge geometry] but a better cutting knife blade, because the truth is, it wasn't really sharp using the original edge grind. Changing the angle just allowed the apex to be singularly addressed making the knife cut better.

Regards, Fred

 

[bucketstove]

there is definitely an advantage to thinning out your blade

20 dps is huge angle full sized felling axes are only 15-18 dps

so if you were to change your edge bevel angle to 15dps with 20dps microbevel, you would see increased performance easily
as you would if you were to change it to 10dps edge bevel with some kind of microbevel
as you would if you were to change it to 5dps edge bevel with some kind of microbevel

if you thin out your edge by 5dps (drop 5dps),
the difference is easy to feel/see when slicing cardboard,
much less muscle is required, much less wedging occurs,
I've done this with dollar store paring knives
... and I read on the internet that edge lasts longer

the difference between 15dps and 20 dps microbevel is harder to feel

1307624-Question-about-thinning-a-knife
that regrind thread by razor-edge-knives

 

[Fred.Rowe]

there is definitely an advantage to thinning out your blade

20 dps is huge angle full sized felling axes are only 15-18 dps

so if you were to change your edge bevel angle to 15dps with 20dps microbevel, you would see increased performance easily
as you would if you were to change it to 10dps edge bevel with some kind of microbevel
as you would if you were to change it to 5dps edge bevel with some kind of microbevel

if you thin out your edge by 5dps (drop 5dps),
the difference is easy to feel/see when slicing cardboard,
much less muscle is required, much less wedging occurs,
I've done this with dollar store paring knives
... and I read on the internet that edge lasts longer

the difference between 15dps and 20 dps microbevel is harder to feel

1307624-Question-about-thinning-a-knife
that regrind thread by razor-edge-knives

I may be wrong but I don't believe that was the OP's question, he wants to know if adding a micro bevel to an established edge will improve the knifes cutting performance. Your points are valid.

 

[cchu518]

Blade steel always matters in that its hardness and toughness affect how it cuts. More important is edge geometry and that means micro bevels as well.
Think of it this way: if you have an edge thats taken to zero at a given angle, in your case 20 dps or 40 inclusive. If it has been taken to zero at this angle and then you change that angle by a degree or two, the sum in your situation being 42 degrees [a micro bevel is always larger] The blade will cut less well, its more blunt, the last angle applied to the edge is more obtuse, making the cross section more blunt, meaning less cutting ability. IMHO, what happens when a micro bevel is applied, assuming the original edge was taken to zero, is a less functional [edge geometry] but a better cutting knife blade, because the truth is, it wasn't really sharp using the original edge grind. Changing the angle just allowed the apex to be singularly addressed making the knife cut better.

Regards, Fred

That makes at of sense thanks for the illumination, I had been wondering if that "other side" of the turnbox and sharpener would be of any personal use to me. I might pick a knife and give it a go.