convex vs micro bevels

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May 30, 2009
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great forum so much info here, im new to knifes and know very little about sharpening and knifes in general. i was wondering if micro bevels are better than the convex edges? is one better for certain cutting jobs? and what tools do u use to sharpen for the convex or micro bevels.
 
i do all of my sharpening with a set of paper wheels for a v edge and for a convex edge i use a belt sander and finish off with the paper buffing wheel. if you want to read more on the wheels here is a thread i started on them and a link to some vids of knives i made and sharpened slicing newspaper. you dont need a leather strop when you are done with the paper buffing whee. since it takes the place of a strop. http://www.bladeforums.com/forums/showthread.php?t=578787
http://sites.google.com/site/richardjsknives/Home/more-knife-pics-and-vids
 
great forum so much info here, im new to knifes and know very little about sharpening and knifes in general. i was wondering if micro bevels are better than the convex edges? is one better for certain cutting jobs? and what tools do u use to sharpen for the convex or micro bevels.
Depends on who you ask"big can of worms", however i believe a convex edge will be a bit stronger in reguards to edge rolling and chipping then a v-grind with a micro-bevel.
 
Depends on who you ask"big can of worms", however i believe a convex edge will be a bit stronger in reguards to edge rolling and chipping then a v-grind with a micro-bevel.

If we want to get extremely technical...a convex edge is just several(read: TONS) closely spaced microbevels.

I grew up in the house of a math teacher. :o
 
If we want to get extremely technical...a convex edge is just several(read: TONS) closely spaced microbevels.

I grew up in the house of a math teacher. :o

Not when you use a soft backing and sandpaper.

Argue away but convex edges will be stronger than microbevels.
 
Not when you use a soft backing and sandpaper.

Argue away but convex edges will be stronger than microbevels.

I'm not arguing. I'm just making a geometry joke.

All a convex blade is is just a collection of closely spaced microbevels.

All a circle is is a collection of closely spaced angles.
 
Microbevels need to have the primary bevel reground once every couple of sharpenings to keep the microbevel small. Convex edges will thin out by itself with sharpening so there is no need resharpening the primary bevel.
 
All depends on whats behind the microbevel / how thick the convex edge is. Basically they are two ways of achieving the same thing - a large primary bevel for good slicing with a steeper angle at the edge for strength. I wouldn't put one over the other, it's up to personal preference.

All a convex blade is is just a collection of closely spaced microbevels.

Exactly, a convex edge is like a microbevel with the ridge knocked down.
 
I'm not arguing. I'm just making a geometry joke.

All a convex blade is is just a collection of closely spaced microbevels.

All a circle is is a collection of closely spaced angles.

Maybe you can help me understand this better but how do you get a bunch of closely spaced microbevels when you are draging the blade on a soft giving surface. You have too much contacting surface area to make many small microbevels.
 
Maybe you can help me understand this better but how do you get a bunch of closely spaced microbevels when you are draging the blade on a soft giving surface. You have too much contacting surface area to make many small microbevels.

I'm not suggesting you can. Sorry if it came off like that.

I'm just poking fun that technically a convex edge is a collection of angles that are closely spaced, thus a collection of several microbevels.

Theoretically, you could put in thousands(millions? billions?) of microbevels until it became a convex edge. In reality, it's not possible. Just like there are only perfect circles in theory, in reality they don't exist.

Edit: Like I said, my mother was a math teacher. I hate math personally, but it's all been drilled into my head. It's just based on the idea that you could place a lot of triangles or squares on top of each other at slightly different angles until you had a circle.

Edit 2: Sorry for derailing the thread
 
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I see your point, the second sentence was not ment towards you just in general, convex talk seem's to make folks up-tight.....not sure why :confused:
 
I personally use microbevels, and don't care to do convex sharpening. However, the truth of it is unless you are using a jig when you freehand an edge there will be some sort of convexing in your edge due to biomechanics. If you are really good the convexing will be minimal, but it is there. Anyway, for me it only takes 5-10 passes per grit on a microbevel to get a knife completely sharp, which saves me a ton of time. When I first rebevel a knife to a thin backbevel it takes a little time, though my DMT XX Coarse hogs off steel super fast, then at that point I refine the edge up to 8000 grit to make it presentable (and sharp), then microbevel at 8000 grit and beyond to finish. Subsequent sharpenings go very fast at the microbevel angle, and I find I get maybe 5 or so sharpenings (sometimes more) before the microbevel thickens and I have to reset the backbevel. With my DMT stones that process is pretty quick.

Convex edges can be strong or weak depending on how thin you go, just like a v bevel with microbevel. I personally have never done convex sharpening, but there are lots of good sharpeners out there that swear by it. It certainly seems simple enough to put sandpaper on a mousepad to sharpen, and I've seen plenty of great pics of the sharpness you can achieve. I say sharpen however you find it easiest to get a good, durable edge that you can get sharp. I have had great results with microbevels, but I certainly wouldn't try to talk you out of convex sharpening. I personally think microbevels are extremely fast to resharpen and I know they have great cutting ability and edge retention when you get the appropriate angles for the steel and usage you are dealing with. Convexing you would have to find that same balance, and I'm not sure how fast resharpening is (I hear it's fast), but until you try sharpening each way you won't know what works best for you. Since a mousepad and sandpaper is cheap convexing might be a great way to start sharpening (some stones get pretty expensive).

Mike
 
right on thanks guys thanks for the info. I might be mistaken but from what I read in other posts the best way to get a convex edge is with a paper wheel system, and for micro bevels most people like the edge pro. but since both tend to get expensive ill try the mouse pad and sand paper for now and save up for the edge pro and paper wheels later on. any fault in my reasoning? thanks again for the help
 
Well, let me wade in and confuse the issue some more.

I like to convex my knife and then put a v-type microbevel on them. Why? for the ease and performance mixture.

1) I like the cutting performance of a convex edge. There is no shoulder at the primary bevel to hang up on.

2) a microbevel edge has such a small shoulder that it doesn't noticably hang up on the material during a slice

3) Convexing the main shoulder of a primary bevel is easy and takes little time, but getting your convex edge to razor sharpness takes a lot of work.

4) I can get usually 5 or 6 sharpenings done on the microbevel, which basically involves 6-10 feather weight strokes on the sharpmaker, before the bevel begins to expand. This takes <1 min to tune the knife. Once the micro bevel begins to expand into a larger bevel, then I knock the shoulder back (re-covex it) using the mouse-pad trick.

This seems to work very well for me. I just find the performance of a micro-bevel + convex edge really great. You get the push-cutting, hair shaving edge without having to go the strop.
 
Well, let me wade in and confuse the issue some more.

I like to convex my knife and then put a v-type microbevel on them. Why? for the ease and performance mixture.

1) I like the cutting performance of a convex edge. There is no shoulder at the primary bevel to hang up on.

2) a microbevel edge has such a small shoulder that it doesn't noticably hang up on the material during a slice

3) Convexing the main shoulder of a primary bevel is easy and takes little time, but getting your convex edge to razor sharpness takes a lot of work.

4) I can get usually 5 or 6 sharpenings done on the microbevel, which basically involves 6-10 feather weight strokes on the sharpmaker, before the bevel begins to expand. This takes <1 min to tune the knife. Once the micro bevel begins to expand into a larger bevel, then I knock the shoulder back (re-covex it) using the mouse-pad trick.

This seems to work very well for me. I just find the performance of a micro-bevel + convex edge really great. You get the push-cutting, hair shaving edge without having to go the strop.

Excellent points, and I largely agree ... was going to post some comments about how convexing and microbeveling don't have to be mutually exclusive, but you expressed it much better than I would have. I don't necessarily agree with you on #1, particularly if you're keeping the overall edge and blade geometry decently thin. But on less acute edges/blades, I think there's some merit to the argument.
 
mantashrimpman, send me an email with your phone number and i'll give you a call sometime and fill you in on convexing a blade and finishing the edge on the paper wheels. today my buddy art summers is stopping by to learn how to grind a full convex blade and i'll be sharpening a few. i'll see if i can get him to take a few vids that i can send you.
 
I broke my rod on my lanskey turn box. looking to replace. Convex guys make fun of micro bevel. so look into buying into it ... (Worksharp belt grinder .. "ken Onion" looks cool) and put it in the tool kit.
The sharpening box. Yes you guys know its a tool box. I'm happy with my edge so ill replace the rod get a new "big" 220 grit stone and just keep going. Great comments all!!!
 
With my Japanese kitchen knives I build a relief bevel at the lowest angle I'm capable of, raise the spine a little and finish the grit progression. Once done, I have a scary sharp convexed edge @ some 20 degree inclusive that won't hold, so I cut a 35 degree microbevel at the right face, and deburr the other one. When properly done there is almost no performance loss. It's all about avoiding any convexing towards the microbevel.
 
I see your point, the second sentence was not ment towards you just in general, convex talk seem's to make folks up-tight.....not sure why :confused:

Because a lot of people say convex is stronger without considering edge angles of each edge bevel. You can have a v edge, Knock the shoulders off and have the apex angle the same, and it will be weaker than the innitial V edge, sort of like taking a convex edge and flattening it out which will make it weaker. If you catch my drift.
 
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