Chisel Grind...Why?

[EChoil]

If you do some quick google image searches for disposable scalpels, while you don't see both sides of each individual scalpel, you'll find countless images showing different models facing both left and right, and a bevel is always clearly visible in each instance. Between this, the 360° image I found and linked earlier, and the opinions of two knife nut doctors who have claimed never to have seen a chisel-ground scalpel, there's a bevy of circumstantial evidence to suggest that they are not commonplace.

Yeah. If you can't find many chisel ground I'm sure I'm not going to either. I guess these days it's a snap to just turn them out double. I wonder if it's reversed and now the exception is the chisel. Kind of looks that way. Which makes me wonder now, what is the chisel specialty required for: where super sharpness is a must?

Now please don't tell me the disposable shavers and average Joe Blow razor blade aren't chisel anymore....

 

[FortyTwoBlades]

Yeah. If you can't find many chisel ground I'm sure I'm not going to either. I guess these days it's a snap to just turn them out double. I wonder if it's reversed and now the exception is the chisel. Kind of looks that way. Which makes me wonder now, what is the chisel specialty required for: where super sharpness is a must?

Now please don't tell me the disposable shavers and average Joe Blow razor blade aren't chisel anymore....

...a chisel grind wouldn't be extra sharp. That's the thing you've been failing to get here.

They'd be used in circumstances where you want to minimize deformation on one surface with little concern for the other (because it would experience an increased degree of deformation) or for making circular cuts where the bias of the deflection forces is of advantage.

 

[Helleri]

If you wanted an inclusive edge angle of 15° on a knife with two edge grinds. You would have to pass each side at 7.5° off the stone/rod...That is insanely difficult to do (by hand, with any amount of consistency, for as long as it takes to do it). Especially if you don't want abrasion marks on the surface of the blade. At that shallow of an angle, taking half a breath can zero you out. Then your getting out the rouges and the buff pads to cover your mistake. Personally I know that 12.5° is about as low as I can safely limbo for long (if I sharpen a knife over several shorter sessions I can get a consistent 10° single angle). Now if one side is already flat (90°), then all you have to do is make passes at 15° on the side with the edge grind in order to have an included edge angle of 15°...It's easier to get sharper if you only have to worry about one side. Because it's less sharpening overall, And it's kinder on the constraints.

 

[EChoil]

...a chisel grind wouldn't be extra sharp. That's the thing you've been failing to get here.

They'd be used in circumstances where you want to minimize deformation on one surface with little concern for the other (because it would experience an increased degree of deformation) or for making circular cuts where the bias of the deflection forces is of advantage.

I keep telling you....I DO see what you are SAYING. But I like checking some things for myself.

I'm still trying to see if I can come over your way on this but what I'm running into more and more--in the little ten and fifteen minute periods I'm finding today to be able Goog and follow some interest in this--is plenty of disposable scalpels offered in "single-bevel" in addition to double (seems the only differentiation by some manufacturers is a product code digit)....and....

a couple of broadhead/archery forums where this same discussion has raved among arrowhead makers and experienced hunters. It's funny because they follow exactly the same script this thread has. All you'd have to do is interchange the names. Same issue---single v. double bevel on arrows, spears and weapons. Cutting ability/sharpness. Good v. eville.

Got a laugh out of it.

 

[FortyTwoBlades]

Bear in mind that "single bevel" may sometimes be used to describe the fact that they are zero-ground. Medical and craft knife manufacturers don't necessarily use the terminology that's become standard in the consumer knife and tool industry/community. These guys, for instance, note that their blades are:

"Ground: 2-sided ground-edge
Blade facets: Single bevel edge-ground"

Would appreciate links, because the only ones I'm seeing any option for single vs. double beveled is with blades that are literally chisel-shaped.

 

[chuxwan]

I typed out a response (twice, damn iPad ) but something happened and its gone. Doesn't matter who says it, a chisel grind still won't be necessarily sharper. I can see why it might be a better grind for broad heads, but it won't be because it's a sharper grind.

 

[EChoil]

Bear in mind that "single bevel" may sometimes be used to describe the fact that they are zero-ground. Medical and craft knife manufacturers don't necessarily use the terminology that's become standard in the consumer knife and tool industry/community. These guys, for instance, note that their blades are:

"Ground: 2-sided ground-edge
Blade facets: Single bevel edge-ground"

Would appreciate links, because the only ones I'm seeing any option for single vs. double beveled is with blades that are literally chisel-shaped.

OK. I follow you. Not disagreeing with any of that. You're enlightening me more.

Here's one I still had up....in the U.K. I think:

http://www.swann-morton.com/product/68.php

"A single bevel version ground on one side only is also available under product code...."


My research time's kinda limited at the moment. I'm not going to pursue this like a grail though.

 

[EChoil]

I typed out a response (twice, damn iPad ) but something happened and its gone. Doesn't matter who says it, a chisel grind still won't be necessarily sharper. I can see why it might be a better grind for broad heads, but it won't be because it's a sharper grind.

Praytell what would the advantage(s) be...more twisting upon penetration? Keep in mind by theory it's a weaker edge.....

 

[ursamajor]

Given two blade blanks of the same dimensions and shape, the tip and edge would be much stronger on the blade with a chisel grind applied.

Not if the grinds were at the same angle.

 

[Helleri]

Bear in mind that "single bevel" may sometimes be used to describe the fact that they are zero-ground. Medical and craft knife manufacturers don't necessarily use the terminology that's become standard in the consumer knife and tool industry/community. These guys, for instance, note that their blades are:

"Ground: 2-sided ground-edge
Blade facets: Single bevel edge-ground"

Would appreciate links, because the only ones I'm seeing any option for single vs. double beveled is with blades that are literally chisel-shaped.

My understanding is that the grind is the working surface for honing an edge. I see it as single grind and double grind (as possible on a blade). And on a grind there is no bevel or back beveled (I don't recognize double beveled as a thing, as that would mean two changes in angle on the grind which unless they are incredibly obtuse is impossible. and if they are obtuse enough to be possible, then it is just a saber grind).... if that makes any sense. Which I hope it does because I don't know how better to word it, lol.

 

[FortyTwoBlades]

OK. I follow you. Not disagreeing with any of that. You're enlightening me more.

Here's one I still had up....in the U.K. I think:

http://www.swann-morton.com/product/68.php

"A single bevel version ground on one side only is also available under product code...."


My research time's kinda limited at the moment. I'm not going to pursue this like a grail though.

Exactly. That's one of the literal chisel blades. It's available with the sharpened flat tip ground on both sides, or only one side. Those are the only ones I'm seeing with that option.

 

[EChoil]

My understanding is that the grind is the working surface for honing an edge. I see it as single grind and double grind (as possible on a blade). And on a grind there is no bevel or back beveled (I don't recognize double beveled as a thing, as that would mean two changes in angle on the grind which unless they are incredibly obtuse is impossible. and if they are obtuse enough to be possible, then it is just a saber grind).... if that makes any sense. Which I hope it does because I don't know how better to word it, lol.

*tags you and leaps from the ring*

I needa get some stuff done here. You talk to him for a while.....

 

[FortyTwoBlades]

My understanding is that the grind is the working surface for honing an edge. I see it as single grind and double grind (as possible on a blade). And on a grind there is no bevel or back beveled (I don't recognize double beveled as a thing, as that would mean two changes in angle on the grind which unless they are incredibly obtuse is impossible. and if they are obtuse enough to be possible, then it is just a saber grind).... if that makes any sense. Which I hope it does because I don't know how better to word it, lol.

A "grind" is just a collection of ground surface bevels representing a modification to the original base stock. These are denoted in the sequence in which they would be applied to the base stock by a maker/manufacturer; that is to say, from the spine to the edge. Any number of these could technically be applied, but typically only one (zero grind) or two (full or saber grind, depending on height of the plunge line) bevels are seen.

The manufacturer I quoted was describing a zero-ground edge (the only bevel being the edge, with zero degrees of relief), with both faces exhibiting a bevel.

 

[BenchCo Spydermade]

Oh my freakin lord folks, this ain't rocket science here. The inclusive angle and steel determine how strong the edge will be. You could hold a chisel ground knife at an angle and the edge would be exactly the same as a v grind and visa versa. But the rest of the knife behind it would make that a bad way to cut lol. The edge is the same if the angle is the same.

Also, I like helleris explanation about how sharpening a chisel grind is easier for more acute angles.

 

[chuxwan]

Praytell what would the advantage(s) be...more twisting upon penetration? Keep in mind by theory it's a weaker edge.....

The broad head is slicing it's way into a solid mass of flesh, unlike cutting something apart, it is actually going to have to slice its own path nearly submerged in the material it's cutting. I'm imagining looking down the path of travel with a broad head coming towards you, the edges would appear almost in a cross section from their normal use, does that make sense? The chisel ground edge will have three surfaces for each (cutting) edge versus four surfaces per edge on v ground heads. Less surface area = less friction. There is definitely some stuff going on with twisting that I don't even want to try and wrap my head around, but there are so many broad head designs that all claim to be the best for a given purpose that I'm sure at least someone touts it as an advantage relating to the grind. That is all conjecture, though. I only said I can see why it might be better for broadheads.
I wholeheartedly reject the "theory" of chisel ground edges being weaker. Both grinds can be weaker or stronger depending on a number of factors, not least of which (and which has been ignored for the most part this entire thread) is the type of strength that is even being referred to.

 

[chuxwan]

Oh my freakin lord folks, this ain't rocket science here. The inclusive angle and steel determine how strong the edge will be. You could hold a chisel ground knife at an angle and the edge would be exactly the same as a v grind and visa versa.But the rest of the knife behind it would make that a bad way to cut lol. The edge is the same if the angle is the same.

Also, I like helleris explanation about how sharpening a chisel grind is easier for more acute angles.

Bingo

 

[Lycosa]

This might be the phat lady!! ^

 

[FortyTwoBlades]

This might be the phat lady!! ^

Oh please oh please.

Regarding tilt, here's a crude diagram I had whipped up last year or so when debating with someone enamored with chisel-ground Japanese "nata" (for their flush-cutting ability) to show how the same effect can be achieved with a double-beveled blade. You just need higher skill to intuit how to align the bevel with your stroke since you don't have that nice visual reference to work with.

 

[Lycosa]

Cool.^
The beat goes on...

 

[chuxwan]

Oh please oh please.

Regarding tilt, here's a crude diagram I had whipped up last year or so when debating with someone enamored with chisel-ground Japanese "nata" (for their flush-cutting ability) to show how the same effect can be achieved with a double-beveled blade. You just need higher skill to intuit how to align the bevel with your stroke since you don't have that nice visual reference to work with.

You probably already know this, but the proper method here is to swing directly in line with gravity while holding the workpiece at the proper angle for material removal. And yes, the same effect can almost be achieved, but you would just be using the wrong tool for the job, just like hewing large timbers with a felling axe. Very doable, but far less efficient and satisfying than with a hewing axe. Having a flat reference face is part of the equation but you can't ignore the energy wasted by cutting at a different angle than you're swinging. Also, the difference is less noticeable with an axe vs broad axe than with a microbevelled knife edge, reference the cliff stamp view here he compares an ESEE Junglas to a Japanese Nata.