Lets Talk t.b.e (thickness behind the edge)

Flat vs convex ...ive dived as deep as I could into that...One thing I can say for certain is that a truly flat bevel on a surface as large as a chef knife can create a glue like bond with many sliced foods...just try it and see for your self. https://www.usgs.gov/special-topic/...ce_center_objects=0#qt-science_center_objects

I only grind in distal taper during a full moon. Contrary to others who may turn into a werewolf during full moons I actually develop cat like reflexes. This is very important b/c it is easy to lose hold of blade, catch the tip, burn fingers or sand them off during this process.

to elaborate:
I am free hand grinding distal taper with my flat platen angled 45 degree from me.
I hold the tang of knife below the platen and then "carefully" place the blade onto belt and "super carefully" apply pressure with my free hand's fingertips in the area I want to sand.
There has been a couple times i lost hold of a blade, burned my fingers or sand the tips of fingers off.
If you try this wear full safety gear. I'm sure there is a safer way. Id prefer to hold the knife above the platen so that if I lose hold its thrown down and away from me but my grinder just not set up that way.
I always stand off the the side a bit when I am grinding these.
 
I will use convex grinds on my own chopping knives but I refuse to put a convex edge on a blade that is going to someone. The convex grind cannot be reproduced even if the person has a belt grinder. I can send a degree wedge with the knife that will allow the new owner to maintain their new knife. If a new owner cannot make the blade as sharp as it was when it was received, then the sale will not end with good results. Fred
 
Fred.Rowe said:
I will use convex grinds on my own chopping knives but I refuse to put a convex edge on a blade that is going to someone. The convex grind cannot be reproduced even if the person has a belt grinder. I can send a degree wedge with the knife that will allow the new owner to maintain their new knife. If a new owner cannot make the blade as sharp as it was when it was received, then the sale will not end with good results. Fred
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Huh. Wisdom in action. Thank you.
 
I recently posted for sale a new sharpening system I developed for the convex knife. When I first made one it was just for me but then it worked so well I decided to manufacture them for sale. I made it for my bark river knives as I was afraid I would damage them on a belt sander. I am still very new to this forum and would love to here your opinions. I would also like to here what you think of putting a convex edge on a non convex knife. I have been doing this to my knives and it seems to work well but I was wondering if there are any drawbacks to it. Sorry I am not trying to steal the thread to sell, this is what I am doing with my knives and wanted your opinions.
 
Fred.Rowe said:
I will use convex grinds on my own chopping knives but I refuse to put a convex edge on a blade that is going to someone. The convex grind cannot be reproduced even if the person has a belt grinder. I can send a degree wedge with the knife that will allow the new owner to maintain their new knife. If a new owner cannot make the blade as sharp as it was when it was received, then the sale will not end with good results. Fred
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I just grind a slight convex to feather down to the edge for geometry, then apply a typical V edge on the stone. Easy peezy lemon squeezy :D

~Paul
My Youtube Channel
... (Some older vids of some of the older knives I made)
 
As for keeping the edge cool gators run a bit cooler. Then belt speed. Add some soap to your dip bucket so it sheets both sides. I know that I can safely grind until the water starts to steam. And if using AO belts spray them with soapy water for a wet grind. At lower speeds they stay wet for over a minute.

I belt finish so my last passes are done vertically with a leather backed platten. Its pretty easy to convex that last bit to near zero that way.
 
Fred.Rowe said:
I will use convex grinds on my own chopping knives but I refuse to put a convex edge on a blade that is going to someone. The convex grind cannot be reproduced even if the person has a belt grinder. I can send a degree wedge with the knife that will allow the new owner to maintain their new knife. If a new owner cannot make the blade as sharp as it was when it was received, then the sale will not end with good results. Fred
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Fred - after working to maintain knives for many years, i get what you are saying. If you do a flat grind, just how thin do you take the edge for the primary (flat) grind?
 
Depends on usage, as you know with putting in a lot of time maintaining blades yourself. Once that is decided upon, then the steel can be selected.
I think that decission [which steel and thickness] should be decided right after usage is discussed. Then ; angle of primary bevel, distal taper or not? How thin at edge before the cutting edge is ground? All these should be addressed right after deciding what use the knife will be put to. Most of us start out making our blades too thick then over time, our blades become more refined and better suited to the job. Progress :) Fred
 
Fred, im writing this knowing i should not :). Not sure if i can really follow your comment .. but that might likely be because of the bourbon(s) i have consumed. :). I will have to have another and see whether things become clearer (again, :). ). Seriously, i think there is a question here... immediate sharpness versus long term mainainability. once again i know i am running up against the potential flames of the forum... but..l what the heck. So again... if one tries a true FFG for a cooking knife (assume some kind of medium level of abuse) what is reasonable to obtain while grinding the primary bevel in terms of edge thickness?
 
This thread has been pure gold.

I was leaving my knives too thick. They cut ok (so i thought) but as soon as the initial sharpness was gone they had to be reshaprened. I started taking them to .010 on the platen and then as thin as possible on the slack. As Stacy said they were sharp before sharpening. Will slice paper without an edge. Granted not too cleanly.

I had a knife in AEBL at about 60 hrc that felt I was a little concerned with as is prefer about 62. I took a 1" but 3" piece of polar and started chopping on the narrow edge. I was trying to imbed the edge as much as possible without chipping out wood. It kept going without damage and still sliced paper cleanly. After a few minutes I started to wedge cut like an axe motion and was still cutting cleanly on newspaper Still no damage so I staterd whacking the flat of the wood. This was rough as the knife wouldn't dig in much and stop with a crisp wack. I was swinging as hard I was comfortable without breaking the handle (wa handle). After about 20 whacks I finally noticed some damage in the form of a slight wave in the edge. Still cut clean with no rolling untill the paper hit that wave.

I can see that a thin edge slices better but once the initial sharpness is gone from the apex you can still have a decent slicer do to geometry.
 
Yeah. I continue to try to go thinner on the grind ... but below about 0.005 I start having problems with pullout (carbides maybe?). Especially with AEBL. But man ... what an awesome edge! Will keep trying with finer grits.... although I think I am seeing more of that pullout with the gator belts... I wonder if others have seen the same?
 
John mc c said:
I can get better results and less risky by bringing the edge to zero on stones
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You finish “grinding” the primary bevel “ie the wide one .. not just the edge) on stones? Sounds like a lot of work... it takes me long enough just with a 120 grit belt...
 
Cushing H. said:
You finish “grinding” the primary bevel “ie the wide one .. not just the edge) on stones? Sounds like a lot of work... it takes me long enough just with a 120 grit belt...
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it doesn't take that long... depending on the steel and if it has soft cladding...
it takes longer to fix your mistakes created on the belt grinder, like low spots or undergrind/overgrind...and when you are done on the stones you have confidence in everything being even and completed.

when you start to get into savvy kitchen knife customers, they want to look at everything.
 
HSC /// said:
i do the same...particularly the longer and thinner the blade like a kitchen knife.
You have to be pretty good at grinding to finish all on the belt grinder.
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I have definitely experienced the challenges with long thin blades.

how thin do you take the edge before coming off the grinder? Keep in mind i am talking about a true FFG... not a grind that is convexed at the edge...
 
I take it as thin as I can as based on the size of the knife and the steel and what I’m working with. That would generally be about .005-.007. But I don’t do a FFG and I’m not sure that it matters for your question
 
It takes very long on hard monosteel but like Harbeer says with a soft cladding is much quicker
I go to about 0.2 mm or a shade less then on to the stones
A disc sander would do in minutes what it takes hours to do on stones but I love my time on my stones.rivals my love of forging
 
HSC /// said:
I take it as thin as I can as based on the size of the knife and the steel and what I’m working with. That would generally be about .005-.007. But I don’t do a FFG and I’m not sure that it matters for your question
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At least in my experience - with a FFG you are removing steel from a much larger surface .... it is just much more steel total to remove to get that edge down in thickness ... it takes surprisingly long...

John mc c said:
A disc sander would do in minutes what it takes hours to do on stones but I love my time on my stones.rivals my love of forgin
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LOL. I guess I just do not have that level of Zen with stones :-)
 
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