Chopper design. Critiques?

S

SLiuGraphite

This is a chopper design that I pretty much stole straight off of gavkoo :rolleyes:
It's his blade design and my handle.
It's going to be made from a 2 1/2" x 48 x 1/4" thick 1095 from Aldo.
What do you guys think? Will it be comfortable?
Also, what edge angle should I have on the chopping portion? I hear a 40 degree inclusive is good.

Choppin.jpg
 
It is a pretty generic chopper design, nothing special, it is ok to use something you like as a starting point as long as it is not a patented feature like a spyder hole or an axis lock. Looks like a good start

-Page
 
Looks good.

Make a wooden cut out in 1/4" plywood and see how the handle feels. Make any changes in that and when you have a wooden one that works well, use it for a template to mark and shape the metal one.
 
Some of the basics - do you want a straight or curved handle ? 6" is a bit long .I have a large hand and the chopper I had made for me has a 5" handle to my specs.Weight in the handle is of no use.That 1/4" tang should be tapered or have significant lightening holes.

Do you want a a gradual curve in the blade or more abrupt as the kukri has ? Your design will give you about 24 oz plenty for cutting substantial stuff. 40* is too much. My use of choppers always seems to be cutting a wide range of things and 40* will be far too much for the smaller stuff , even too much for large stuff. I suggest 20* for light stuff and 30* for heavy.
 
The long handle is good but make sure you can get at least two different grips out of it. One that's close up for whittling/carving, and one farther back to move your hand away from the COG and get more power. In other words, don't put any silly grooves or notches that prevent this. What you have shown there looks good- that swell is all you need for retention.

I don't care for choils, if I want to hold it close-up to the blade I would rather hold the handle than the blade. I'd bring the front of the handle right up to the plunge line, which would make it like 7" long. But lot's of people seem to like the choils, so you won't be in bad company if you keep it.

What kind of grind are you going to do? That will have a big effect on how it balances.

I agree with mete that 40 deg is too obtuse if you are most concerned with performance in wood. What you need to think about more is thickness behind the edge. That knife will weight 1.5 lbs + and that's a tremendous amount of force on the edge when it slams home. On that note, I think most people would recommend a lower carbon steel than 1095 for a knife like this. 1060, 5160, S7, Calmax, 3V are more typical choices for blades like this. That said, 1095 is not the worst choice i the world, either. Just keep the embrittlement zones in mind when you temper.
 
KyleGrantham said:
Dont steal from Mike like that just buy one from him
Click to expand...

Well I would, but it's nearly impossible to buy one from him. He hasn't made one in quite some time and they're pretty expensive.

bladsmith, I was actually thinking of going to Michael's and buying a big block of modeling clay to use.

mete, I think the reason the handle is so long is because it starts really low. Like, the first choil starts about 1/2" behind bare steel.
I measured the distances on my hand and I THINK this will be comfy. I guess I'll have to make a prototype.

Robs92XJ, the reason I have the choil in the blade is so I can get closer to the center of gravity and have multiple grips.
Now I'm thinking around a 25 inclusive so I can have the best of both worlds. I'm not sure exactly how I'm going to do the grind but I want the chopping portion to be
a saber convex and the other parts to be a full height.
I'm going to get it heat treated by Darrin Sanders here on the forums. Gonna request around 56 HRC.

Thanks for all the help guys!
 
SLiuGraphite said:
Robs92XJ, the reason I have the choil in the blade is so I can get closer to the center of gravity and have multiple grips.
Click to expand...

You misunderstand me. I like the idea of being able to position your hand in different spots to affect the balance point. But you can just move the handle up into the area where you have the choil now. To me that is much more useful- it would be something I'd look for as a prospective customer. But many people seem to like choils. I'm just a hater, I guess.

SLiuGraphite said:
Gonna request around 56 HRC.
Click to expand...

If you are going to run it that soft, why use 1095? You will have to temper at a little over 500 degrees, which is in the embrittlement zone. If I understand the implications of that correctly, then you would actually have less toughness at 56 rc than if you tempered at 300 deg (which would be around 60 hrc). The blade at 54 rc will not only be soft (meaning it will dent and roll easier) it will also be more prone to fracture under force of impact.

If you were to use 1060, you could achieve 56 rc by tempering at 400 degrees, staying well out of the embrittlement zone. It should be much tougher than the 1095 blade.

Note: I am referencing an ASM Heat Treater's guide for the above "metallurgical" content. Hopefully other knifemakers will correct me if I am wrong.
 
I see what you're saying now. That'd look kinda funky though. An almost 7" handle. I'll try it and see.

ESEE has there blades at 56-58 HRC.

If anyone else has info on what hardness I should use for this it'd be greatly appreciated :p
 
Hardness isn't the only consideration. Edge geometry is gonna have a lot to do with the proper hardness. For a 1095 chopper, if you have a good beefy edge in the neighborhood of .020"-.025" then do a final convex 58-59 will be fine and edge holding will be much better.
 
SLuiGraphite, Darrin makes a very valid point, but Robs92XJ also has a point - for a knife this long I'd have thought 1095 to be a little brittle. If you are going to use it, then try for around 58HRC, but I think you should perhaps look at making this one from EN45, 1060 or 5160..
 
Part of the 'temper embrittlement ' is a factor of steel quality which has improved over the years and is not nearly the problem. To choose a proper steel you don't need the higher carbon steels like 1095. 5160, 1084 and really nice is CPM 3V , for good choices.
 
I drew it with the 7" handle no choil. Looks really weird! Haha, I'll stick with the choil this time.
I already have a couple of bigger knives that I'll be doing in 1095 but I guess i'll save this design for when I get some of that 5/16" 1075!
I would love to do this in 3v but I'd rather not spend so much on the steel when I'm not sure how these first few knives will turn out.

Thanks for the help everyone!
 
Lol. That isn't what I mean, I mean to say bring the scales up some so they conform to the edges of the choil, that way when you use the choil the metal doesn't dig into your fingers. For instance, look at how the scales come up around the choil on the Laser Strike. It's hard to explain.:( Other than that small detail, very clean design!
 
SLiuGraphite said:
I drew it with the 7" handle no choil. Looks really weird! Haha, I'll stick with the choil this time.
I already have a couple of bigger knives that I'll be doing in 1095 but I guess i'll save this design for when I get some of that 5/16" 1075!
I would love to do this in 3v but I'd rather not spend so much on the steel when I'm not sure how these first few knives will turn out.

Thanks for the help everyone!
Click to expand...

5/16? that is too thick for a useful knife. 1/4 inch with a full flat grind would be best

-Page
 
Looks cool man. I agree with the "generic chopper" look, but that's probably why I like the looks of it. I also like the idea of either 5160 or 1075. Keep us updated!
 
You must log in or register to reply here.
Back
Top