Why *not* a six inch serrated tomato knife?

[Cushing H.]

if you p.m me we could talk a

The system would not accept a pm to you...

 

[Pinoy Knife]

if you p.m me we could talk a

I'm afraid if I were to try to do that, it would just end up looking sloppy.

if you contact me via p.m we could talk and i could tell you how to do it .. or you can try to figure it all out for yourself.. your

 

[Cushing H.]

if you p.m me we could talk a

Pinoy ... i believe you need to have a membership above basic to allow for pm discussions...

 

[Pinoy Knife]

left ya a message

 

[Cushing H.]

left ya a message

I am not receiving anything from you…

 

[Hubert S.]

I maybe understand, but really not sure. Could you pls post a photo at your convenience?

Here is a picture that hopefully explains what I meant. The fixture plate would go between the blade and the 1-2-3 block so you can clamp the blade securely and support the overhanging parts of the blade. If you have a way to rotate your vise ninety degrees, it would be worth doing that, otherwise you might run out of room, depending on the length of the blade and how long the tang is.

 

[Cushing H.]

Here is a picture that hopefully explains what I meant. The fixture plate would go between the blade and the 1-2-3 block so you can clamp the blade securely and support the overhanging parts of the blade. If you have a way to rotate your vise ninety degrees, it would be worth doing that, otherwise you might run out of room, depending on the length of the blade and how long the tang is.

Ahh, I get it now. Thank you! Looks like I need to order some 123 blocks, and buy or make a fixture plate…

 

[Pinoy Knife]

take away the end mill and use a carbide tapered burr.. while you are at it don't use the 123 block..
if you put o rings on the contact wheel and use a flex belt will it not conform to the shape below??
Cushing i saw what i posted this morning !! you must be tech challenged like me (ha-ha_) on your profile page..

 

[Cushing H.]

take away the end mill and use a carbide tapered burr.. while you are at it don't use the 123 block..
if you put o rings on the contact wheel and use a flex belt will it not conform to the shape below??
Cushing i saw what i posted this morning !! you must be tech challenged like me (ha-ha_) on your profile page..

Pinoy - I dont know what to tell you. The system will not allow me to post a PM to you (though it does allow me to post a PM to other people). Also, neither do I have any unopened messages in my incoming PM list. I also believe that you have to have a membership level *above* a free standard level to participate in PM activities. Technically challenged??? well, I will let others judge that.

You may be right about the belts and o-rings approach, but I guess that its just that I happen to have this nice mini mill, and I just want to try doing the serrations with that approach. If it messes things up, I guess that is my risk...

 

[Richard338]

Pinoy - I dont know what to tell you. The system will not allow me to post a PM to you (though it does allow me to post a PM to other people). Also, neither do I have any unopened messages in my incoming PM list. I also believe that you have to have a membership level *above* a free standard level to participate in PM activities. Technically challenged??? well, I will let others judge that.

You may be right about the belts and o-rings approach, but I guess that its just that I happen to have this nice mini mill, and I just want to try doing the serrations with that approach. If it messes things up, I guess that is my risk...

Look at your profile on this site. He posted a message to you on it (not a PM).

 

[Cushing H.]

Look at your profile on this site. He posted a message to you on it (not a PM).

Thanks for the heads up. Profile posts ... and area that I never look at, and to which I receive no notification when someone posts to it, but which is not the same as a PM. go figure.

 

[Hubert S.]

take away the end mill and use a carbide tapered burr.. while you are at it don't use the 123 block..
if you put o rings on the contact wheel and use a flex belt will it not conform to the shape below??
Cushing i saw what i posted this morning !! you must be tech challenged like me (ha-ha_) on your profile page..

The tapered burr is a great idea, that way you can clamp the blade in the vise directly, much more rigid and you can do both sides at the same time without having to index the second side.

 

[Cushing H.]

Just a slight update. Received those diamond dremel compatible chainsaw sharpeners. They produce a finish in the serration that is WAY to rough. Looks awful. I suspect any file will have the same issue. Still back to pursuing the milling idea. A 3/8 mill followed up with a 3/8 ceramic rod *might* produce a reasonable finish?

I also suspect that the need to get consistent spacing and depth might well push me over the edge to getting a dro for the mill...

Pinoy - ill try calling you again today.

 

[FredyCro]

Another question for all the serration experts. Should the bevel be one sided or two sided? Should the angle of the serration be different then the primary bevel (before sharpening). I noticed that a bread knife I have is ground from one side only and the serration have a shallower angle then the primary bevel. Then the serrations have a secondary bevel. This is what you see on pocket knifes as well, although primary grind is double sided. Another thing is also that you can angle the serrations away from the cut. Or that serrations are just perpendicular to profile and then the secondary bevels and ground (ie no bevel angle on the serrations). So many guestions. If I were to try it I would put the serrations at an angle before heat treating and then after HT grind one side only. Finally sharpen with diamond rod and/or sandpaper and debur the flat side.

 

[Cushing H.]

Another question for all the serration experts. Should the bevel be one sided or two sided? Should the angle of the serration be different then the primary bevel (before sharpening). I noticed that a bread knife I have is ground from one side only and the serration have a shallower angle then the primary bevel. Then the serrations have a secondary bevel. This is what you see on pocket knifes as well, although primary grind is double sided. Another thing is also that you can angle the serrations away from the cut. Or that serrations are just perpendicular to profile and then the secondary bevels and ground (ie no bevel angle on the serrations). So many guestions. If I were to try it I would put the serrations at an angle before heat treating and then after HT grind one side only. Finally sharpen with diamond rod and/or sandpaper and debur the flat side.

Freddy ... i am certainly no expert, but can relate what i see. On all my commercially made serrated knives, they are all double sided bevels, but the serrations are ground on one side only. Also, to my eye, all serrations are cut at a 45 degree angle from the center plane of the blade .

I also have noodled on the idea of milling the serrations perpendicular to the plane of the blade, but keep thinking that will create a dead spot to trap food in, and will interfere with a clean cut.

For ease of making the thing, right now i am thinking in terms of milling 3/8 inch serrations at 45 degrees on the *left* side of the blade, heat treating, then grinding a *single* bevel on the right side of the blade. This will create circular depressions where the ground bevel intersects with the milled serrations, but maintain either a tip or sharp flat between serrations (depending on separation between serrations). For a tomato (not bread) knife ... i am also wondering about possibly grinding a Ura on the left side of the blade.

Fwiw..

 

[Cushing H.]

Slight update. I had a chance to play around on my milling machine yesterday. Still not set up to angle anything in my vise ... but i do have a conical burr.

First thing, it is pretty straightforward to get evenly spaced and even depths on the serrations, even without a dro. i think though that my estimate of 45 degrees on the bevel is in fact way off. Problem is that when you grind a bevel on the opposite side, you do in fact produce the characteristic scalloped hollow, but you also "eat away" at the rounded bottom of the hollow, and leave very little angled "trough" to the bevels.

I *think* this will be changed by using a steeper angle... but i think i need to do some trigonometry and do some good old pencil and paper sketching to convince myself of that...

 

[Storm W]

I sharpen serrated knives by polish the inside. I have a water wheel sharpener that has a leather wheel on the other side or I use something like a cork belt and just run it over the corner. Then polish the other side.

I have not heard of anyone who has out up any good photos or evidence that shows that what Larrin showed in his study when it comes to sharpening. I have said before that I thought that unrefined so called toothy edges were just things that guys made up because they couldn't sharpen. I figured that I had to give it an honest try. They weren't wrong. The more I learn about abrasives and how they cut it makes sense to me at least. I think between the increased surface area of the high volume grit and the fact the edge gets flexible and can't hold the pressure to cut and after a certain point the grit no longer cuts and just burnishes the edge. If that's what is going on it would explain why edge retention drops by a fatigue mechanism and with any catching and fatigue it would possibly damage the apex. I am probably thinking about it wrong but I can't think of a reason why course grit can't give the same Apex. If the angles are the same if the grit is cutting it should give the same Apex. I also get that a more polished edge might be better but there has to be a point when the grit stops cutting. Polished edges heritage come from razors and ultra low alloy steel that would be easy to cut. The majority would not have any carbide at all. That would mean that the natural stones would probably still cut it down to a finer grit. Many historic knives were under 50 Rc. I shave with a straight razor and much of the polishing has to do with comfort. I have a 66 Rc M4 blade sharpened on diamond stone and it is nearly as sharp at 300 grit. If I dropped the angle and switched to 600 grit it would probably be sharper. It could be an experiment to use different hardnesses and carbide volume and see how it affects sharpness and edge retention. I know that using a DMT Course will get my knives shaving sharp after a quick strop. It only takes a max if 2 minutes to get a knife there if it hasn't been sharpened in years and 3 strokes per side whenever it no longer easily shaves. For me unless I have a specific need it is just to hard not to use an easy way like this to keep my knives tuned up like this. I don't need everything perfect. If they shave easy they are good enough unless I am doing something special.

From my experience a "toothy" edge does a great job. If you can push cut tissue paper you can do it with tomatoes but if you draw the cut the blade eats the tomato.

 

[Cushing H.]

I sharpen serrated knives by polish the inside. I have a water wheel sharpener that has a leather wheel on the other side or I use something like a cork belt and just run it over the corner. Then polish the other side.

I have not heard of anyone who has out up any good photos or evidence that shows that what Larrin showed in his study when it comes to sharpening. I have said before that I thought that unrefined so called toothy edges were just things that guys made up because they couldn't sharpen. I figured that I had to give it an honest try. They weren't wrong. The more I learn about abrasives and how they cut it makes sense to me at least. I think between the increased surface area of the high volume grit and the fact the edge gets flexible and can't hold the pressure to cut and after a certain point the grit no longer cuts and just burnishes the edge. If that's what is going on it would explain why edge retention drops by a fatigue mechanism and with any catching and fatigue it would possibly damage the apex. I am probably thinking about it wrong but I can't think of a reason why course grit can't give the same Apex. If the angles are the same if the grit is cutting it should give the same Apex. I also get that a more polished edge might be better but there has to be a point when the grit stops cutting. Polished edges heritage come from razors and ultra low alloy steel that would be easy to cut. The majority would not have any carbide at all. That would mean that the natural stones would probably still cut it down to a finer grit. Many historic knives were under 50 Rc. I shave with a straight razor and much of the polishing has to do with comfort. I have a 66 Rc M4 blade sharpened on diamond stone and it is nearly as sharp at 300 grit. If I dropped the angle and switched to 600 grit it would probably be sharper. It could be an experiment to use different hardnesses and carbide volume and see how it affects sharpness and edge retention. I know that using a DMT Course will get my knives shaving sharp after a quick strop. It only takes a max if 2 minutes to get a knife there if it hasn't been sharpened in years and 3 strokes per side whenever it no longer easily shaves. For me unless I have a specific need it is just to hard not to use an easy way like this to keep my knives tuned up like this. I don't need everything perfect. If they shave easy they are good enough unless I am doing something special.

From my experience a "toothy" edge does a great job. If you can push cut tissue paper you can do it with tomatoes but if you draw the cut the blade eats the tomato.

Hey Storm. My hat is off to you for shaving with a straight razor - I just would not even think about it (too many nasty movies about that when I was younger I guess....).

I *think* that part of the argument about highly refined polished edges has to to with reducing cellular damage to vegetables (and raw fish) leading to discoloration and off-tastes (but I am only referring a few comments I have read in the past...).

One question - you comment " a "toothy" edge does a great job. If you can push cut tissue paper you can do it with tomatoes but if you draw the cut the blade eats the tomato" .... Im not sure how to interpret that. by "blade eats the tomato" do you mean it chews it up and destroys it .... or do you mean it slices the tomato easily????

 

[Cushing H.]

Looks like it is Goldilocks time........ Ive been experimenting with different angles to mill serrations at. Started at 70 degrees - it was too shallow. tried 80 degrees, it was TOO long. Then tried 75 degrees - which was JUST RIGHT .

3/8" end mill, what is shown is serrations at 0.042" separation (center to center). This would give a little flat between the serrations, which I am thinking I would want. the second photo shows the serrations next to the blade I am proposing to mill them into. Again, I am thinking single bevel on the side opposite of the serrations, and maybe with a Ura ground into the side with the serrations..... (oh - unfortunately my vise does not open enough to get the 123 block into the thing with the 3" side lengthwise in the vise :-( I might need to create a fixturing plate to hold the thinner blade securely enough ......

 

[Hubert S.]

That looks like it will work! I think some support will be needed on a six inch blade, otherwise you have two inches of thin material flopping around on either side. It is hard to tell from the picture how you have the blade clamped, but it does not look right to me. There seems to be a plate behind the 1-2-3 block which I presume you use as a clamp. The end away from the blade appears to touch the block. I think you should put a spacer in there slightly thicker than the blade. I would also recommend to move the blade to the other side of the block, that should make it more rigid. If you set it up like in the picture I posted, the blade does not have to stick out above the 1-2-3 block, which should make the setup a bit more rigid.

I looked at the geometry the other day a bit, and the depth of the serration you will be left with appears to be quite sensitive to how you grind the bevel and obviously how deep you machine the serration. It might be worth grinding a quick bevel on the other side of your test piece just to make sure you end up with something reasonable. The 80 degree serration might be preferable if you machine it less deeply, maybe with a 1/2" end mill.