How can you go full convex? Ride the whole blade width then finish out the edge?

Yes. Takes a long time.

No doubt!

KnifeGuy, great looking blades...all of them!

Thanks.... I wish I had time and opportunity to use a bunch of them as much as Vic. <img src="/ubbthreads/images/graemlins/blush.gif" alt="" /> <img src="/ubbthreads/images/graemlins/frown.gif" alt="" />


In continuation with your interest on how full convex blades are created:


I would tend to say the "Full" Convex is probably best, but sometimes for the sake of ease, time and if there is desire to save blade shape and mass (applies in some cases), I often only re-grind/re-profile the edge to a highe convex edge that tapers reaonably smoothly into the side of the flat grind. .... And call that good enough for my purposes. <img src="/ubbthreads/images/graemlins/blush.gif" alt="" /> <img src="/ubbthreads/images/graemlins/thumbup.gif" alt="" />... Depends on the blade and how much I feel like messing with it. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

For the record, if intending to go full convex, it is actually easier/better to re-grind a saber grind to full convex - compared to trying to full convex a full flat grind - (although, like Vic says: it can take a long time - in either case. - Although, I am sure if you have the right equipment, right belts and do it daily, you can probably breeze through a LOT faster..... ?????).

The problem with grinding a full height flat grind to convex is that you can (tend to) end up grinding the thickness of the spine down significantly to create the full convex which can change the knife a lot.

So, with full flat grind, I would almost always just stop at convexing the edge.

If you can visualize the flat profile of a saber grind vs. a flat grind, the saber grind alread possesses a much closer to convex grind than a flat grind. On a saber grind, for the most part, you would just be blending the angled shoulders between the grinds into one smooth curve, that (in theory) could start from the initial edge to the initial spine without changing them much..... not changing the edge and spine much takes a fair amount of practice.

However, a flat grind, just by nature, pretty much has to have the spine ground down to create the convex. - Pretty much geometrically impossible.

Of course, grinding a saber grind into a full convex can change the knife a lot too. But, at least you can keep the spine thickness pretty close.

Imagine - I doubt you want to try to "strop" a most any non-full convex grind to full convex - it would take forever.

Here is a pic of how Mike Stewart grinds a full convex blade with a 2"x72" high end grinder:




The convex sides and edges are created as one. But, then, as you mentioned, you can go back with finer grits and finish the edge to a finer more polished edge.

However, even when finishing just the convex edge, you would lay the blade pretty close to flat on it's side again. Just tilt the blade a degree or so more and lighter feathering touches to sharpen on the finer grits.

Notice Mike grinds the primary grinds on the belt sander with the edge cutting into the belts.

I have had good luck with this on the coarse grits. And I know Vic has mentioned he now convex grinds edge first now as well.

I believe by grinding this way it is just much easier to see what and how you are grinding. And I think as long as you don't angle the edge of the blade into the side of the belt this technique works very well on the coarse grits. I think the coarse grits and stiffer backed belts work well with this technique without cutting the belts because the blade floats on top of the grinding media without cutting into the belt.

I don't know about Vic and Mike, but while I have had good luck with the coarse grits, I do NOT grind edge first when "Sharpening" with the finer belts. I have cut a few belts that way.

While I have been lucky and haven't damaged myself, my knives or anything else when cutting the belts, I find the belts popping to be VERY unsettling.... and have to assume in the wrong situation it could cause damage or harm.

Especially if you are trying to lift the spine of the blade a bit to focus on the edge. This causes the edge to be focused too directly at the belt.

***** I have to HIGHLY recommend NEVER sharpening edge first into "leather" belts on power equipment. I could be wrong, but that seems like a recipe for disaster. The leather belts are WAY tougher to cut through than the fine grit abrasive belts. A decent edge will just slice right through the fine belts and then the belt just flaps through the machine a bit and off the machine.

But, a tougher leather belt (I assume) would be VERY prone to grabbing a knife and ripping it out of your hand = recipe for disaster! <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" /> <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" />

When stropping manually, I strop with the spine leading and edge trailing as well. <img src="/ubbthreads/images/graemlins/thumbup.gif" alt="" /> So, I don't know why you would try to sharpen edge first into a powered machine on the finer grits and again especially not leather.

Light pressure to just the weight of the blade (depending on the blade) seems to work the best for sharpening via manual strop or power stropping..... that and patience. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

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I don't see much point in doing a full convex on most flat grinds. They already are thin toward the edge anyway, so I just blend the convex to the flat grind like I did on this RD6.

Thanks, KG, I'm not planning on taking any of my blades to full convex anytime soon. I'm always happy with flat ground blades and my little belt sander puts a decent edge on FAST. That is one of the big plusses for me. With other sharpening methods I have tried I could easily spend an hour making a dull knife sharp.

The HRLM looks like the ideal canidate to go full convex.

+1 .... I agree.

Sorry Imagine,... I was going into too much detail on your commment getting you mixed up with Stabby who doesn't (appear to) have a belt sharpener and has been discussing manual strop stuff - from above.

Then you mentioned full convexing and being mixed up was thinking you might be trying to full convex with a manual strop. <img src="/ubbthreads/images/graemlins/blush.gif" alt="" /> Too much in my head. <img src="/ubbthreads/images/graemlins/doh.gif" alt="" />





Actually, it probably is a GREAT candidate to make full convex. The blade on the HRLM is Plenty thick and it wouldn't hurt it to remove some metal.

But... sometimes I like the looks of a nice Saber grind.

I tend to lean towards function first. But, sometimes I let a nice look be a factor. It still cuts well with a blended high convex edge into saber. <img src="/ubbthreads/images/graemlins/thumbup.gif" alt="" />

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KG, as long as you don't mind getting carpal tunnel from typeing <img src="/ubbthreads/images/graemlins/frown.gif" alt="" /> I'm sure everyone appreciates the info <img src="/ubbthreads/images/graemlins/bowdown.gif" alt="" />!

Thanks... no real worries about carpal tunnel.... But, I REALLY should be working on other things like hunting for a new job to help my finances. <img src="/ubbthreads/images/graemlins/frown.gif" alt="" />

I will work on that some tonight. <img src="/ubbthreads/images/graemlins/banghead.gif" alt="" />

What are you doing now, work wise?