How sharp can it be?

[richard j]

I think this whole thread was started by the OP as a thinly veiled marketing thread for his Bubble Jig which (if I recall correctly) allows you to set up precise angles relative to gravitational vertical so you can easily reproduce bevel angles. When I was making stock removal knives in the typical style that most factory (and a lot of handmades) are done with a flat area near the spine and a bevel that is a uniform height and angle coming up from the edge to meet that flat, a device like the Bubble Jig would have been really handy for making uniform height and geometry bevels, thankfully I have taken my style into a more fluid direction, so I no longer make knives to look machine made, and my geometry is based more on the form of the blade when I am done with the hammer than any rote geometry, and the edge is a matter of how aggressively sharp can I make this with the steel and heat treat I am using and have this edge stand up to my customer's use. I try to keep as many variables under control in my metallurgical process so I can be as free as possible with the rest of it

-Page

i'm talking to fred right now and it has nothing to do with his "bubble jig". not once did he mention his "bubble jig". we talked about basic angles and guided sharpening systems and how some fail to give you the promised sharpening angle on every blade.

 

[J. Oeser]

I don't want to pick a fight, but I do think your assertions are out of place. I strive for hand-made quality, not machined perfection. I have never used or needed a special sharpening system to take the error out of sharpening, and you seem to imply that I am remiss in that regard.

If the precise edge angles on your knives are a marketing point, then by all means use that with my blessing to sell your knives. But please don't drop it in my lap like a challenge, or use it to publicly point out the errors of others (as you percieve it). The right way/wrong way mentality detracts from the diversity and beauty of our craft.

This was what went through my mind as well when I read the OP. I try to do certain things on my knives to let people know that this was made by hand, by a person that is imperfect. I suppose I could make everything look machined but that's not my style. And while I know approximately the angles on my grinds and bevels most of what I do is done by feel and based on real use performance not a digital read out.

 

[Fred.Rowe]

I don't want to pick a fight, but I do think your assertions are out of place. I strive for hand-made quality, not machined perfection. I have never used or needed a special sharpening system to take the error out of sharpening, and you seem to imply that I am remiss in that regard.

If the precise edge angles on your knives are a marketing point, then by all means use that with my blessing to sell your knives. But please don't drop it in my lap like a challenge, or use it to publicly point out the errors of others (as you percieve it). The right way/wrong way mentality detracts from the diversity and beauty of our craft.

Good morning Sir!

This is all about conversing, exchanging ideas, give and take. Anytime I post a thread that ask a question I hope other people will express their opinion. I believe that is what happened.
If I state my opinion I am doing so with the understanding that it is just that, an opinion and not a truism. Any conversation amongst people of differing opinions is best approached with each person not believing their opinion is the correct and only real truth.
My apologies if you took my statements as an assault on your knife making skills or approach. Nothing could be farther from the truth.

I am interested in what you have to say, Fred

 

[Fred.Rowe]

I think this whole thread was started by the OP as a thinly veiled marketing thread for his Bubble Jig which (if I recall correctly) allows you to set up precise angles relative to gravitational vertical so you can easily reproduce bevel angles. When I was making stock removal knives in the typical style that most factory (and a lot of handmades) are done with a flat area near the spine and a bevel that is a uniform height and angle coming up from the edge to meet that flat, a device like the Bubble Jig would have been really handy for making uniform height and geometry bevels, thankfully I have taken my style into a more fluid direction, so I no longer make knives to look machine made, and my geometry is based more on the form of the blade when I am done with the hammer than any rote geometry, and the edge is a matter of how aggressively sharp can I make this with the steel and heat treat I am using and have this edge stand up to my customer's use. I try to keep as many variables under control in my metallurgical process so I can be as free as possible with the rest of it

-Page

Page,

I don't do thinly veiled anything. If I want to market my invention, I do so in a manner that is accepted by the forum I am posting on. You will find any marketing threads for my invention posted on the proper forum. I always check with the mods to make sure I am doing things in the accepted manner.

I apologize for making you feel like you had to criticize me and what I make in order to make your point and to quantify your own work. I've seen what you make and it stands on its own.

The term "machine made" refers to the fact that a Bridgeport mill can consistently perform work that a human hand can not. So when I say striving for machine like finish it refers to the desire that all makers have to produce blades without gaps and imperfections. You know perfection. That has nothing to do with style its about finishing a knife to perfection. I figure you are no different.

Regards, Fred

 

[sunshadow]

Page,

I don't do thinly veiled anything. If I want to market my invention, I do so in a manner that is accepted by the forum I am posting on. You will find any marketing threads for my invention posted on the proper forum. I always check with the mods to make sure I am doing things in the accepted manner.

I apologize for making you feel like you had to criticize me and what I make in order to make your point and to quantify your own work. I've seen what you make and it stands on its own.

The term "machine made" refers to the fact that a Bridgeport mill can consistently perform work that a human hand can not. So when I say striving for machine like finish it refers to the desire that all makers have to produce blades without gaps and imperfections. You know perfection. That has nothing to do with style its about finishing a knife to perfection. I figure you are no different.

Regards, Fred

No blood, no foul.

Actually your Bubble Jig is an ingenious approach to some common issues and problems, and a simplification of a device I made for setting up angles on my milling machine, and another device I made back when I was setting up alignment in optical paths in enlargers at RIT. I apologize for the cynical tone of my post

-Page

 

[Fred.Rowe]

In the illustration below are four blades with four different bevel grinds. From the left side the first blade was ground with a three degree bevel on each side. The second a six degree bevel. The third a nine degree bevel and the last one a twelve degree bevel, or as some would call it a scandi grind. The blades are highlighted in yellow. All four blades are ground to a zero edge.
Each of these blades was sharpened using a 12 degree angle per side or 24 degrees inclusive.

Even though all four knives have distinctly different bevel grinds and thicken at the spine as the degree of grind increases, all four of them will cut exactly the same along the edge of the blade. Each will cut the same with exactly the same pressure applied. The two main differences is how the blade looks in profile; The three degree bevel grind will show little indication of the sharpened edge where as the 9 degree ground blade will show the top portion of the sharpened edge going halfway up the bevel.
Secondly, of course a knife is not just an edge of sharpened steel there is the blade and its geometry to consider. How thick, how wide how long. How does the blade perform when cutting in the real world.

Back to my original premise; A knife can be sharpened without knowing what angles were used in grinding the bevels; or for that matter the angle used to sharpen it, a twelve degree edge is just that two intersecting planes with an inclusive angle of 24 degrees. But knowing the angles adds a lot to the users knowledge of the knife. Knowing the angles of the bevels allows the person to make the best sharpening choice for a specific blade and its use.

This thread and all threads I start are never posted, looking to condemn or marginalize anyone's technique or manner of making knives. They are posted with the hope of generating discussion and the sharing of knowledge. There is a huge amount of collective knowledge that makes up the knifemaking community, the small amount of knowledge I possess does not stand alone.

Fred

 

[me2]

Half the reason I started making my own knives and regrinding old ones was to set the angle and edge geometry the way I wanted. It would be a nice change if all the manufacturers would tell us what the edge angle is, and be right, and why they chose that angle. The same goes for individual makers, though the question receives an answer from the individual makers much more frequently.

 

[butcher_block]

yep we are back to trig angles can only ne messed with so much
but whil you say that they all cut the same on the edge i say that as soon as you are past the edge (who reallys only uses the edge ) the bevel grind can maka worls of difference

if you wantto do the math i make 3/32 spine full flat ground 2.5 inch tall kitchen knives that have a pre sharpened "blunt"edge of .007 or less and ten put 10-15 degree edge on them depending on buyer and use

btw fred your first post as i read it and saw it edited (no clue as to why) made me think that you were hand slapped about marketing your jig. thats jsut how i took it at my first read so i can see how others might have thought that
just saying that cause of the edit it seemed liek maybe you posted and the mods said now now make it less salesy

i do thank you for makeing more look at what angles they are grinding there blades both bevels ad edges

 

[Fred.Rowe]

yep we are back to trig angles can only ne messed with so much
but whil you say that they all cut the same on the edge i say that as soon as you are past the edge (who reallys only uses the edge ) the bevel grind can maka worls of difference

if you wantto do the math i make 3/32 spine full flat ground 2.5 inch tall kitchen knives that have a pre sharpened "blunt"edge of .007 or less and ten put 10-15 degree edge on them depending on buyer and use

btw fred your first post as i read it and saw it edited (no clue as to why) made me think that you were hand slapped about marketing your jig. thats jsut how i took it at my first read so i can see how others might have thought that
just saying that cause of the edit it seemed liek maybe you posted and the mods said now now make it less salesy

i do thank you for makeing more look at what angles they are grinding there blades both bevels ad edges

Morning Butch!

Without looking, I think that was my point; we don't just cut with the edge of a blade. Its whats going on behind the edge that really counts. That is what I was trying to show with my drawing. Sharpening angles are influenced by bevel grind angles.

I self police as much as possible; there was no visit from the mods and no edit to tone it down.
Making what I make and most people on the forum knowing this, its hard for me to mention the word angle without the assumption that I'm in sales mode.
Its more about; coming from an engineering background and now working with my invention for 5 years; I see angles in my sleep. No joke.
So when ideas like this come to me, awake or asleep, my first inclination is to share the thought the second is to ask for opinions and see how other people perceive it. [

To be completely honest, its exciting to me when I drop in on a thread and hear people talking about blades in terms of geometry, angles, longitudinal spirals and the like. I see blades as a collection of angles and lines. I know its a little weird but its the engineer in me.
I think its a positive that the conversation is changing. Not just changing but elevating. What I read now on the forums as compared to what was being talked about 6 or 8 years ago is astonishing. No more threads about edge packing a blade.
Some of the discussions on in depth steel analysis make my head hurt. Its great! I love it.

Like most of us hear my hope is that what I say and the ideas I share add something positive to knife making. Simple as that.

Thanks for posting, Butch. I am always interested in whats on your mind. :thumbup:

Fred

 

[butcher_block]

i keep all this in mind cause of the 2 main blades i make kitchen and razors
really not many more extreme uses of steel for an edge
more fun numbers
a 6/8 razor might be .200 thick at the spine but if it is a full hollow it wil be under .010 nearly half way up the blade

 

[Rick Marchand]

I spend much more time getting everything behind the edge working the way I want. I now bring the bevels down to .005-.007" prior to sharpening. The way I see it, a customer can reset the final edge to whatever he wants. Of course, there are limitations set by the spine to edge bevels. Full flat is... well, full flat. At that point, the customer should be looking at "spine thickness vs. blade width" with regard to finding a suitable knife geometry.