Sharpening ???

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jmh58
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Sharpening ???

#1

Post by jmh58 »

I am going to keep this as simple as I can so I understand the answers.. Say.. If you want a micro-bevel at 30 and a main bevel at 20 (just throwing numbers).. Do you do the micro first than main or vice-versa?? And do you bring up the burr on the micro or ??? And elaborate on what/how does inclusive mean?? I have been sharpening for more yrs than I will admit but some of this stuff I don't understand... I just sharpened till I got what I wanted.. :eek: I use and fixed (KME) system and have no desire to use any thing else.. Thanks.. John :)
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paladin
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Re: Sharpening ???

#2

Post by paladin »

this could go on for a long time, so I try to keep it as brief as possible... :eek:

Cliff Stamp is an advocate of "erasing" an edge sometimes when you're faced with a major resharpening task. Basically, drawing the edge across the corner of your sharpmaker rod or hone at an angle perpendicular to the hone itself a few times. This is a tip that I have found helpful. :)
The idea behind "erasing" is that you remove an apex containing steel which may be damaged from over-fatigue or sharpening on power equipment. You get into the "good" virgin steel-- accomodative terms.

sharpen at 30 deg initially, that should be enough to remove the shoulder from the primary grind, make sure you are hitting the apex before you move on... The "sharper," "steeper," ie more acute angle, is useful to remove enough metal from "behind the edge" ( the shoulder ) allowing yourself easier access to the very edge itself, the apex...you should be able to slice magazine pages easily if done correctly. This is sharp enough for most folks, but if you want to help refine your edge's sharpness you need to move on...

now grind the secondary bevel ( the "edge" you just ground ) with a few light passes at 40 degrees...this is what Sal calls a good "working edge"...a good balance of sharpness & enough beef behind the edge to avoid rolling & chipping in most cases. You should be able to shave arm hair pretty easily at this point.

with this method you need only go back & touch up the secondary with a few 40 deg. passes for a few sharpenings (depending on how heavy duty your cutting chores are) until you need to go back to 30 deg. to remove the "shoulder" again, thereby making it possible for you to sharpen to the very edge apex effectively.

a "microbevel" means different things to different elu's, for some, it means further refining the apex by very, very lightly making a few more passes at an even greater angle than your last 40 deg. setting...

a good loupe or manifying glass is helpful to let you see better what you're doing after a few passes...but remember with sharpening it is a constant battle to try to "hit the apex." Light passes will help keep from forming a burr.

Glossary:
primary grind- the first grind the maker employs when fashioning a blade out of the blank...often speaks to what folks call just "the grind" of the knife, ie saber, hollow, flat, etc.

secondary grind- the second grind the maker employs to make what is commonly called "the edge" of the knife.

apex- the very tip edge of the secondary grind, where the actual matter separation of cutting takes place on an edged tool.

burr- an apex that has been over stressed, incorrectly ground, or otherwise pushed to the side of the optimal location for most cutting tasks.
Last edited by paladin on Sat Apr 25, 2015 4:40 pm, edited 1 time in total.
yablanowitz
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Re: Sharpening ???

#3

Post by yablanowitz »

jmh58 wrote:I am going to keep this as simple as I can so I understand the answers.. Say.. If you want a micro-bevel at 30 and a main bevel at 20 (just throwing numbers).. Do you do the micro first than main or vice-versa?? And do you bring up the burr on the micro or ??? And elaborate on what/how does inclusive mean?? I have been sharpening for more yrs than I will admit but some of this stuff I don't understand... I just sharpened till I got what I wanted.. :eek: I use and fixed (KME) system and have no desire to use any thing else.. Thanks.. John :)
"Inclusive" is about the total included angle between the two faces of the bevel. The SharpMaker (and other systems as well) has markings that are only the angle between the face of one bevel and the centerline of the blade, or degrees per side. When someone says "It's sharpened at 30°", they may mean 30° total (inclusive) or they may mean 30° per side, for a total included angle of 60°. That gives you a very tough edge that doesn't cut very well even if it is shaving sharp. Yes, a 60° edge will shave hair if it is cleanly apexed. So will a 90°. I've seen a lot of factory edges in the 50° to 60°included angle range.

As far as "bringing up the burr" goes, many people seem to think that is critical. I've been sharpening for about 50 years and I think they are wrong. Forming a burr is a sure sign that you have removed more steel than you needed to, and a probable sign that you are using too much pressure. The goal is to get the two sides to meet cleanly. A burr says you've passed that point.
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bearfacedkiller
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Re: Sharpening ???

#4

Post by bearfacedkiller »

I try to avoid bur formation. A bur is made of fatigued metal and you do not want any of that in your edge. When I try to explain sharpening I tell people that sharp is simple and that sharp is when you have produced a clean apex of unstressed and undamaged steel. This is the reason that I try to avoid bur formation in the first place, it reduces the possibility of realigning the bur into your finished edge. No bueno.

My take on bevel and micro bevel is that you first form an edge by apexing your blade at 30 degrees ( or less ;) ). You may produce a very good edge doing it just this way but you also may (due to inconsistencies in angle while sharpening) produce a less than perfect apex. After apexing the edge at 30 degrees even if your apex is a little sloppy you can then move to 40 degrees and do just a few light passes and that will form a good clean edge/apex. It is the lower number of passes reducing any variation due to user influence that can ensure a good edge/apex at this 40 degree angel. This forming of a microbevel will also remove any microbur you may have formed which is also good. From here on out you can just touch your knife up at 40 degrees until you can visibly see the micro bevel growing. When the microbevel gets bigger then you will want to reset the 30 degree bevel and start this process over. One main benefit of doing it this way is to reduce the amount of metal you need to remove in order to produce a new edge. As the microbevel grows you are needing to remove more metal each time. With a small microbevel you are removing so little metal that it usually does not take very many passes to reestablish the edge/apex.

I cannot emphasize enough the benefit of a sharpie and a loupe when getting the hang of all of this. It lets you see exactly what is going on.
-Darby
sal wrote:Knife afi's are pretty far out, steel junky's more so, but "edge junky's" are just nuts. :p
SpyderEdgeForever wrote: Also, do you think a kangaroo would eat a bowl of spagetti with sauce if someone offered it to them?
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paladin
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Re: Sharpening ???

#5

Post by paladin »

just readin' back over my post...

I didn't want to imply I was keeping it "simple" to insult your intelligence...it kinda can be read that way... :o

I meant I was keepin it simple so that I wouldn't write too much... :eek:

Also, sorry if I was being a little too "teachy" ...I just wanted to explain it well-- plus you must forgive me because that is my profession also :D
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ChrisinHove
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Re: Sharpening ???

#6

Post by ChrisinHove »

I would say it was "succinct" rather than "simple", and very informative, so thanks!
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