blade thickness, is 3/8" just too thick?

N.N

N.N

Well-Known Member
I did a quick search and found Ed talking about blade thickness but nothing as specific as I am curious about.

I have a potential customer who wants a 5" 3/8" thick blade that can be used as a chopper when needed. I don't think he intends this to be a dedicated chopper. I find that my 3/16 thick 5 inch blades are plenty thick and work well for light to medium chopping and don't have overly strange length to thickness proportions.

I've suggested that we don't take this 5" blade any thicker than 1/4" as I think that would be a pretty beefy knife as it is. I also don't think I want to trust my heat treating methods on something so thick. I would most definitely send it off.

What do you guys think? I'd just like to get some opinions from those that have a little more experience with larger blades.
 
No expert here, but I'd tell the guy no, unless he's willing to pay more. I've made one similar size to that in 3/16" and one in 1/4", both seem plenty thick for anything you'd need. The 1/4" one even looks odd to me, too thick for a 5" blade. The other problem with a 3/8" blade, is how much steel you're going to have to grind away. If you go full flat grind, that's a lot of material to remove.
 
3/8" thick is appropriate... for a kukri or big seax. It would be totally unnecessary in any blade less than 10" long, IMO. To get a good cutting geometry you would need the blade to be very wide, 1 3/4" or wider. To me it just doesn't make sense if the blade is only 5" long.
 
I agree with these guys. At only 5" long in the blade, it will have horrible cutting geometry. Tell the guy to buy a hatchet.
 
I did tell the guy to buy a hatchet:shush:...then I realized he didn't need a knife if he bought a hatchet and quickly reversed course to explain how well a 3/16" knife works at that size.

I'm going to try and get him to come by the shop Saturday and show him a few of my 5" knives at 3/16", let him beat on a 2x4 with one for a minute and see if he thinks he really needs sharpened plate armor or a knife.
 
For a 5" knife I haver used anything over 1/8"- 5/32" and those were plenty thick!

Things have gone quite nutty in the past 5-10 years in thickness with sharpen pry bar knife looking implements.

When I get these kinds of requests I ask them if they have any knives of same length, that were used by their father or grandfather and how thick are/were those knives?

WWII was the largest mobilization of men and materials ever on the planet, how thick were the 5" knives we sent our troops to war with and how many of those knives are still around today?
 
You are right, of course. My post should have said, "Tell the guy to buy a hatchet to chop with and one of your knives to slice things with." :)

Good for you for having him come over. Hopefully you can get him educated on the subject.

I totally agree with Laurence here. It has to be the 'zombie/apocalypse age of the internet' that has people thinking their knife must cut car doors and hoods, chain link fence, smash through cinder blocks and cut doors off their hinges. That kind of thinking is ridiculous. Knives cut and slice stuff........that's it. Any task beyond slicing and cutting and I guarantee you there is a much better tool for it than a knife. No matter how well someone thinks a knife chops, it won't do it as well as a decent axe or hatchet.

I get the fact that you can blur the lines a bit and make a knife that does several things decently. I'm not really talking about a camp knife that may split some kindling, trim back some brush and slice some meat and veggies for the camp meal. That I get. I still maintain that any knife that does several different things won't do any of them as well as it could if it were tailored to a single task.

I think people would be surprised if they knew how thin some of the knives of the frontier days were. They actually used their knives then and knew that those thick blades didn't slice worth a hoot. Not to mention the fact that there weren't a lot of power tools around in those days and no one wanted to grind or file away that much steel.
 
All good points from better and more experienced makers than myself, however, I'll offer a couple additional thoughts.


Every knife is a compromise. Building it for a specifice use or purpose will limit its abilities in other areas. The customer or end user (sometimes that's the maker) needs to be aware of that and accept it.

Personally, I like a good knife over a hatchet for chopping. That means a blade in the 10" range with a good heft, around 5/16". I think it chops better that a hatchet, and utlimately has more versatility for other woods tasks. It won't fillet a fish or skin a mouse real well, but for more delicate tasks, I also have a smaller blade, usually drop point in the 4-5" range.

A knife's chopping capability is more about balance, i.e., blade heavy, and that will be difficult to achieve with a 5" blade, regardless of thickness. Assuming you're making a full-tang, you can taper the handle portion or drill it out. A hidden tang is a bit easier, but will still be a challenge. As noted above, don't forget to charge for the extra time and materials, including belts, that you'll use.

To have any sort of decent cutting ability, it will also need to be quite wide or deep, with a full flat or possibly hollow/saber grind.

For comparison, both of these blades are a solid 5/16", the smaller has a 6" blade:

http://knifedogs.com/showthread.php?38870-Matched-set

I was able to make it a high saber grind, but as you can see it is signifigantly wider. It cuts great, although it won't slice and dice veggies like one of Laurence's fine blades, and has ok chopping ability, certainly not axe-like, but again, it's all about compromises.

Check out the Boker Vox Rold (I happen to have one for sale, but that's not my point). It is a very well-designed, balanced knife that excels at a lot of tasks, is able to do a little chopping, and that's only about 3/16" thick. After handling and using one (the one for sale is an extra), I am planning on eventually making something similar in 1/4", which I think would be about perfect.


Finally, even though I'm partial to large blades, I agree the whole zombie thing has gone to a whole new degree of craziness. Not that there's anything wrong with new degress of craziness, if for no other reason that to have a good reason to buy or make another knife.

Oh yeah, 3/8" is too thick.
 
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All things certainly are relative aren't they. :)

Let's look at strictly chopping for a minute and forget everything else. If a given knife chops better than a hatchet, I can only draw one of two conclusions:

A: It's not a very good hatchet

B: If it's a good hatchet and the knife still chops better, it's probably not much good at knife related things. :)

My original point was to use a knife for knife things, i.e. cutting and slicing things and use other tools for other tasks. Actually, I think anybody should use whatever they want and whatever makes them happy. Just to be clear. :D

I guess more to the point, if a knife excels at chopping over a good hatchet, it is highly unlikely that it is the best knife it could be for slicing.

Also to be clear, I didn't mean that one should make a knife with only one task in mind. More like design a knife with a group of similar things in mind. You can choose to make thin keen edges that slice well but wouldn't hold up to much chopping but boy do they cut like the dickens. Or you can make a knife that chops well but won't slice as well as it could. And then I'm back to the first part of this post.

I'm not trying to be contrary and argue with you firecog (or anyone else). Just trying to be clearer on my approach and way of thinking. I like knives with keen edges that slice really well. :)
 
I use 3/8 all the time on my bowies but the blades are 11+" for a 5 inch blade 3/8 is completely unnecessary and impractical. It would look ad perform very poorly.
 
I think this guy just wants something beefy and doesn't realize 3/8 looks a lot bigger on a knife blade than when looking at a ruler.

To furthered discussion, I think a lot ofpeople including myself like to have to carry as few tools as possible. If you can have a large knife for defense that can chop and cut decently, you can take care of more tasks with less weight. Most people just don't understand thruout going to have to seriously torture 3/16 steel to bend it. I don't know. I might do the 1/4 just to do it and see how it turns out. I think he's military as well, so fine slicing probably isn't as big a concern anyway.
 
J. Doyle said:
I'm not trying to be contrary and argue with you firecog (or anyone else). Just trying to be clearer on my approach and way of thinking. I like knives with keen edges that slice really well. :)
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I don't really see us being in disagreement, just a slightly different approach to accomplishing the task at hand (or in hand), and in both posts, I think your thoughts were expressed very elegantly.

I'm also extraordinarily jealous of your work every time you post. I keep telling myself that someday, maybe someday, I can make a knife like that...
 
Give him a 1" wide, 8" long piece of 3/8" stock and tell him to carry it around for a few days... let him know his knife will weigh roughly the same amount. Within an hour he will see how impractical his idea is.
 
N.N said:
I think this guy just wants something beefy and doesn't realize 3/8 looks a lot bigger on a knife blade than when looking at a ruler.

To furthered discussion, I think a lot ofpeople including myself like to have to carry as few tools as possible. If you can have a large knife for defense that can chop and cut decently, you can take care of more tasks with less weight. Most people just don't understand thruout going to have to seriously torture 3/16 steel to bend it. I don't know. I might do the 1/4 just to do it and see how it turns out. I think he's military as well, so fine slicing probably isn't as big a concern anyway.
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Ok, then if he actually is serving in our Military suggest he go with an American Bowie type design of at least 7 to 10" in length. A 5" blade is really long enough to do much chopping in my experience.

My last point here is if you make the blade tall enough? You can get 1/2" thick steel to slice well with a full flat grind.:3:
 
rhinoknives said:
My last point here is if you make the blade tall enough? You can get 1/2" thick steel to slice well with a full flat grind.:3:
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The American bowver (bouie/cleaver) at 6 inches long, 1/2" thick and 5 inch bevels, it does everything!
 
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