Comp Cutter geometry/balance questions

[David Schott]

I am a good way into making a competition cutter and so far have the blade almost fully ground pre-ht. So far I have stuck as close to the max guidelines as possible, with a 1/4" thick O-1 blade, 10" tip to scale front, 5" handle for 15" OAL. Blade is nearly 2" wide in the sweet spot, tapering a bit thinner at the ricasso.

I am making this full tang with an integral guard in the scales. I have skeletonized the tang fully and moved the balance point about 3.5" in front of the choil.

Questions:
Balance point: In a perfect world, where will I want the whole knife to balance? I could probably move the balance point to within 4" of the tip with some creative skeletonizing (Read: hacksaw out sections to make a framed tang).

Spine: Do I want some sort of false edge? My grind is currently full to the spine for the length with a distal taper beginning about 1/3 back. How about fully radiusing the spine? I have seen cutters in both styles. I am not a big fan of false edges, for the record, but want to do it right. Ive seen some with and some without...was thinking the main advantage may be in weight reduction and reduced drag?

Drop: Do I want to drop the point lower than the midline of the blade to throw weight for chopping towards the belly of the blade? What fraction of blade height do you guys usually drop for a heavy chopping/cutting knife?

Scales: I plan on using 3/8" g10 for the scales, sanded to a rough 180-320 grit for grip. I was thinking of them masking off a few sections and applying a rubberized bed liner for trucks for added grip...No wood on this one!

Any answers or insight would be great!

 

[Stacy E. Apelt - Bladesmith]

Sounds like you are well on the way to a great comp-chopper.The handle should have a good grip,yours sounds excellent.Drop the point a bit extra to allow more edge contact in chopping.For a chopper the balance point,and thus the center of inertia,should be wherever you want the blade to contact the 2X4.Roughly the center of the blade.Round the spine and forget the false edge.
Stacy

 

[D.sylvester]

make a real big handle just for mace and so some of us can hold it with out tweezers

see you there
david

 

[the possum]

I got some questions about the competition guidelines myself.
Is 1/4" thick the maximum? The spine on my hunting knife made by Bill Moran was thicker than that at the base.
Is the choil/ricasso area considered part of the handle or part of the blade? I.E., where do they begin and end with the 5" measurement, etc.

Balance point: In a perfect world, where will I want the whole knife to balance? I could probably move the balance point to within 4" of the tip with some creative skeletonizing

I've been devoting a lot of thought to balance these days. I have never been in a cutting competition though, so others could probably give you better ideas of the specifics. That said, I have a good enough working knowledge of the concepts that I was able to make a big bowie that maneuvers & swings faster than a machete, and chops with more authority than my 32 oz HI khukri. This is the result of good balance. Got your attention yet?

You're starting off on the wrong foot by thinking that the balance point determines the *dynamic* balance. Two knives of the same length and weight and same balance point may handle and chop totally differently. So don't ask where the balance point should be- it will end up wherever it has to as a side effect. Ask yourself what portion of the blade you want to chop with. (near the tip where you have more speed?) Where will you place your hand during chopping? (i.e., will you maintain a normal grip or choke back & hold onto the butt?) How will you swing the knife? (i.e., how much wrist rotation, and where will that rotation happen?) Do you want to be limited on what portion of the blade you can use, or would you prefer more versatility?

Back to your knife-
I'm afraid that if you tried concentrating that much mass at the tip, you'll end up with a blade that is fairly slow to swing. Axes have their optimal striking point at or near the balance point, but historically blades like swords and such have been balanced somewhere between 20%-40% of the total length from the butt. In the latest Blade, our own Roger P wrote an article about the evolution of Dan Farr's competition knives. Dan finally settled on a blade with less mass near the tip, using more taper and even a fuller to reduce weight.
A false edge at least at the tip would help its thrusting ability, which could come in handy if they have any point-oriented tasks like the ping pong ball stab they've done in the past.

 

[David Schott]

Thanks!

I have now Ht'd this one...HT went well. Did four normalizing cycles then brought it up real slow. Out of quench, the blade tested hard enough and went in for 2-2 hour tempers at 400 and 425. I left the spine fully radiused.

As for balance, it will change as this develops. My guess is it will end up about 4" in front of the ricasso. I will have to see how this first proto comes out and play with handles and such to see how it performs. I quickly took a section down to a wide, thick convex and it performed well. I can't wait to see it at a thin cross section...I will be doing a decent amount of testing pre-scales to ensure the edge can hold up to heavy impacts. I would rather be on the tough side than brittle side....

I will prolly have this done in a week or two when I get some shop time. I have enjoyed making this one so far!