LightChopper WiP

Lorien

Lorien

Nose to the Grindstone
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Knifemaker / Craftsman / Service Provider
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Dec 5, 2005
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Hey folks; I posted up this WiP in the C&H forum, but I think its true home is here:)

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Good day, forum!

I have a WiP here for you, but I'll tell you up front that it will be a little while before we have a completed knife to show.

In the meantime, I hope that you enjoy the 'design backstory', which in itself is something of a WiP

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Around a year ago, Nathan Carothers and I started working on a project near and dear to my heart. Our goal is to produce a large, high performance forest blade. Kind of a large camp knife/small machete.

The idea here was to develop a relatively lightweight knife, (about 1lb) which wouldn't be overly burdensome for carrying, but that would pack a punch all while sporting a high performance bevel profile. We didn't want a knife meant for chopping into cinder blocks or cutting through a car door, but something for your more experienced outdoorsperson. It could be used to clear a trail, prepare wood for a fire, dig if necessary, or make a shelter.

Below, is the first version I came up with. It's designed to incorporate a mortised handle, which is why the tang looks so funky. I'll spoil the surprise and tell you know that this one was scrapped, but it will serve to show the progression of this particular project.






Stay tuned...
 
We kinda let the original design sit for awhile, and my sense was that Nathan was not so keen on it. Looking back, I understand why- not only is it somewhat ugly, the method of manufacture, vis a vis handle design, is a little out there and quite different from the standard and trusted approach.

Coming up with a pattern, putting it on the back burner and then returning when the time is right seems to be a pretty dependable approach for me. Sometimes I get it right off the bat. Most times, it's a process.

I wanted to present Nathan with a pattern that he would be well and truly stoked on. I also wanted a less brutish looking tool; more Lamborghini than Humvee.
The following is the pattern that ultimately made it's way to Nathan's shop, and it reflects what I was trying to achieve quite well.

Keeping in mind that this is a collaboration, and collaborations necessarily involve the goals and visions of all parties concerned in its development, so this isn't the last iteration you'll see.

 
The next step, after figuring out the profile, layout, specifications etc. is to get a handle on the handle.

Envisioning what I'd like to achieve is always tricky, but I can confidently say that all those years in art school were not wasted! I'm no great artist by any stretch of the imagination, perhaps not even average, but I've gotten so much practice at drawing that I can express what I see in my mind's eye on paper well enough to convey graphic ideas to others.

Drawing in 2D to give a sense of 3D is an adequate start, but building the object in 3D is the only way to really get the idea across, in a measurable way. Apart from making a knife, this will be the first time I've developed a pattern and incorporated a 3D element to it. That was Nathan's suggestion, and it just might have been the best advice I've gotten when it comes to designing knives. But that's for another post.

I took a tracing from the original to create a paper model. Doesn't cut very well, but it does really give a good sense of layout and geometry when interfaced with the human appendage meant to utilize the final product.
 
Like I said at the outset, the outcome from my end would incorporate Nathan's aesthetic preferences and manufacturing techniques. Many small changes were made the result is what you saw in my last photo.

Before I sent the scaled model and original sketch to Nathan, he asked me to explain what I was thinking wrt handle design, primarily. Below is my answer.

I know, tl;dr But still, it might provide additional insight into this project if you care


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there are a number of handholds; choked up, forward grip with thumb on spine, chopping grip, and two reach enhancing grips.

behind the guard, the grip flares out toward the platform in the middle of the grip where the grip is the widest. It is swelled at this point and then tapers until it reaches the pommel, which is bulbous and aids retention is the rearward, reach enhancing grips. The handle dimensions are slightly oversized. In my experience, a grip that is a little fatter decreases the chances of cramping and is more comfortable during heavy use.

the scallop at the jimping is a hook for the web of skin between thumb and fore finger. In the choked up position, with the index finger in the choil, (which is chamfered), this scallop pulls at the web of skin there, providing no slip grip. The jimping should be semi aggressive, in that it will be a little deep, but with the chamfered spine shouldn't cause much in the way of a hotspot for this grip position which if for fine cuts, not chopping. The front of the handle also features one scallop per side, which gives more comfort and control in the choked up grip.

the forward grip, with forefinger immediately behind the guard, places the pad of the thumb over the jimping for controlled chops. The ring finger sits at the platform in the palm swell, providing massive grip strength, keeping the knife from sliding forward in hand during repeated chops. The ring finger is the 'judo' finger and provides a very strong grip

the chopping grip places the pinky right at the beak of the handle to lock the hand in. The curvature of that area bunches the pinky and ring finger together, creating an awesomely strong judo grip, while the middle finger rests on the platform, which has some flat planes, to keep the knife from twisting laterally under heavy loads. The kick at the top of the butt interfaces with the heel of the hand, providing a platform to control swing-through and arrest forward motion of the knife quickly. Both the beak and the heel kick are rounded so as to avoid hotspots. The web of skin between thumb and forefinger wraps over the palm swell, providing an elastic interface for snap cuts.

as the hand moves back on the handle, middle and ring fingers move into the pinky well and the forefinger rests at the palm swell platform to aid in lateral control. The pinky wraps behind the pommel. This grip increases tip speed, leverage, reach and power at the expense of control. Only to be used with a stable target.

the other rearward grip places the pommel in the palm, with fore and middle fingers in the pinky well. This is only a reach enhancing grip and wouldn't provide enough control for safe chopping.

the lanyard hole is at the front of the handle, below the scallop. It would be a flared tube. I didn't drill my model out because it's cedar and delicate. For a chopper, a forward lanyard is superior in the sense that, used correctly, it can be a power multiplier and slingshots the blade. It is also more effective at arresting the knife mid swing.

the handle is designed with two stabbing grips; one with the thumb over the pommel, and the other choked up with the handle completely gripped

the blade would have a fuller, in order to increase surface area, decrease overall weight and because you can do it and it will look cool. The grind is designed to get steeper out toward the tip in order to have a slightly fatter edge up there which would handle abuse better.

I haven't designed the handle skeletonizing, as I thought I'd leave that to you, but I certainly can draw it in if you like.
 
for someone who uses acronyms regularly, I sure hate them sometimes.

Nathan sent me his thoughts on the approach taken toward turning this idea into something useful;

some thoughts on a FFG

Dan Keffeler recommended a fairly narrow range for the primary grind angles, which was substantiated in my research leading up to this project. So, for me coming into this, certain aspects of the geometry were predetermined values. When you're starting with a specific geometry that starts at the edge, you'll see that to do a FFG would require a more narrow blade or a thicker spine. A narrow blade loses impact energy flexing. A thicker spine would be useful on something where you want a heavy blade, but isn't what I wanted on a lighter woods knife.

Also, a FFG doesn't work well with a fuller. I like using a fuller on something like this so we can adjust the distribution of mass with the blade cross section rather than being limited to changes only in the profile.

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Keep in mind that you are still at the sketch phase. Many changes have occurred since then, so don't take any of what you've seen thus far to be the final word.
 
Crazy. I posted a "where are the WIP threads" thread at the exact time this one was brought over. Eerie. Great minds......
 
there's a lot of that going on in this forum....
 
I seem to be having issues moving the photos from the original thread over here.
in the meantime, go here if you can't wait :)
 
Lorien said:
I know, tl;dr But still, it might provide additional insight into this project if you care
Click to expand...

We care :thumbup: And you are very thorough. The thought process is always interesting to me. Thanks.
 
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