Impact splitting, Byrd Finch, Opinel, Ratweiler

[Cliff Stamp]

Byrd Finch :



The size of the knife limits the wood and the opening hole reduces the impact which can be used because all that is resisting the splitting is the little strip of steel above the hole. Note this doesn't load the lock significantly because the impact is between the knife and the wood. Further illustrated by :



The impacts are much heavier here which allows the split to be done much faster, since you can apply much more force it basically directly enhances the cutting ability. The Opinel is a spring tempered piece of carbon steel so there is also no concern about the impacts from the axe. The lock on the Opinel was not engaged in that splitting so this can be done on any folder with little concern, even on slip joints.

Ratweiler :



That was some light splitting, there was a knot but it went through fairly easily. The next piece is a little more difficult but still nothing serious :



The next piece is fairly demanding. In the middle I open my off hand as the impact vibrations are so high I don't want to try to damp them out directly. When the blade meets the heavy knot in the middle there is almost no travel per impact as it is chisel cutting right through the knot :



A shot of the knot :




-Cliff

 

[kel_aa]

Maybe it's time to move into a condo, Cliff.

 

[knifetester]

That's why he is splitting the wood, for his new condo complex. . .
Just wait until it is time to cold chisel the rebar!!

Again, adding video to your reviews and posts puts things in a whole new perspective. I can not express how much more meaningful these videos are than the just reading all those words.

 

[Cliff Stamp]

Maybe it's time to move into a condo ...

Got to clear the lot first.

I can not express how much more meaningful these videos are than the just reading all those words.

Yeah, a lot of things like "hard impact" or "forceful prying" or even "cut smoothly" can be hard to judge unless you were there. Even if these are calibrated the numbers like 125 ft.lbs or 1.5 ft/s don't mean a lot to most people.

All of the above knives were reground by me to be much more acute than the factory edge. Even the Ratwelier is heavily thinned to a convex profile which is about 8/10 at the shoulder and only thickens to about 13/15 in the very edge, 1/64" or so).

-Cliff

 

[knifetester]

While those may be radically thinned edges, it is not the edge I would expect to see failure at in most baton use. The edge is often only in contact with the wood the first few strikes, especially with thicker, hollow ground blades (Livesay Air Assault for example) or saber flat ground knives. After the first few strikes, the wood is riding on the shoulder of the primary grind (saber grinds) or near the spine thickness (full flat grinds). Often with really thick knives (5/16" or so) or with axes you see the wood splitting ahead of the knife edge.

This is heavily dependent on wood type as well.

"hard impact" or "forceful prying" or even "cut smoothly" are more meaningful to me even if totally subjective, than numbers like 125 ft.lbs or 1.5 ft/s even if they appear to be objective.

If someone like Joe Talmadge says a knife is thin edged, slices well" it means something in context.

 

[Cliff Stamp]

.The edge is often only in contact with the wood the first few strikes, especially with thicker, hollow ground blades (Livesay Air Assault for example) or saber flat ground knives. After the first few strikes, the wood is riding on the shoulder of the primary grind (saber grinds) or near the spine thickness (full flat grinds). Often with really thick knives (5/16" or so) or with axes you see the wood splitting ahead of the knife edge.

When this is happening the only real concern is through strength, does the blade have the necessary strength to not actually warp. You can see machetes fail in this manner for example. However the biggest concern I have seen for most knives is on knotty wood where the blade will bind heavily right at the edge, and when the edge is going through a knot, this force is concentrated at the edge. So for example if you take a bowie and grind the primary right down to 0.010" then the edge will buckle very easily on such wood, or at least every steel I have seen to date would do so.

"hard impact" or "forceful prying" or even "cut smoothly" are more meaningful to me even if totally subjective, than numbers like 125 ft.lbs or 1.5 ft/s even if they appear to be objective.

They are objective, however this doesn't mean they are meaningful to an individual person. This requires a knowledge of the units. I would not have known if that was a large or small impact until I actually measured a bunch of them and saw what it meant in terms of effort.

The problem with subjective statements is they are are user dependent. I have read for example statements praising the cutting ability of knives which were 30+ degrees per side at the edge and 1/8" thick. I don't even have a viewpoint to describe that it is so negative.

What can make these statements meaningful are just benchmarks "The Rugheld carved birch easily twice as good as the Endura." is a lot more meaningful than "The Rugheld carved birch like a laser." This is where the forums come in because people can ask for comparisons to knives they have used.

-Cliff