True flatgrind?

[Fletch Helical]

I've seen this term used from time to time and not really sure that the difference is between a true flatgrind, and a flatgrind. Anyone care to shed a little light to a noob?

 

[galadduin]

I've seen this term used from time to time and not really sure that the difference is between a true flatgrind, and a flatgrind. Anyone care to shed a little light to a noob?

I didn't notice there is a term as "true" flat grind. I happen to know there is a term as "full" flat grind which is one bevel meeting at the spine. May be "true" one is a bevel meeting at the edge with no secondary bevel...

Emre

 

[george tichbourne]

Flat grinding to the very edge results in a very sharp but weak edge. The only use for this is on kosher slaughtering knives to my knowledge.

George

 

[silver_pilate]

Yeah, I'd hesitate to go to a zero-bevel edge with a flat grind. I've done it by doing a full flat grind, leaving my typical 1/32 or so at the edge and then convexing the edge portion of the flat grind into a zero bevel edge. That gives you a scary sharp edge with more meat behind it, though it's a bit tougher to sharpen for most customers.

--nathan

 

[Nathan the Machinist]

Perhaps they're talking about a truly flat grind to differentiate from a slack belt "flat grind"?

 

[galadduin]

"slack belt" flat grind ?????
I wasn't aware of I could grind flat on slack belt D:

 

[Fletch Helical]

Perhaps they're talking about a truly flat grind to differentiate from a slack belt "flat grind"?

Maybe, I wouldn't know what the difference between the 2 would be. It's possible to flat grind without having a platen in place?

 

[Nathan the Machinist]

Oh, I don't think you can. I guess you can come pretty close on a rotary platen. I was simply speculating that in the context of whomever was using the term "true flat grind" was trying to differentiate it from a not true flat grind. Just guessing at what would have been meant by that....

 

[P.Brewster]

Technically, a "flat" grind isn't flat, unless the cutting edge is perfectly straight. It's impossible to configure two planes so that they intersect to form an arc.

Perhaps "true flat" describes a grind that is composed of two "truly flat" planes.

 

[Fletch Helical]

Maybe when I've seen it then they were referring to a full flat grind? I occasionally do searches for various terms in google or yahoo and read through several web sites from whatever comes up. Guess it's true that you can't believe everything you see on the internet

 

[Nathan the Machinist]

Technically, a "flat" grind isn't flat, unless the cutting edge is perfectly straight. It's impossible to configure two planes so that they intersect to form an arc.

Perhaps "true flat" describes a grind that is composed of two "truly flat" planes.

Yup, the best you can do is "flat" in one direction, meaning a straight line can be drawn from spine to belly in some orientation (probably about normal to the belly). That is the conclusion we came to last time that question came up. :thumbup: