What is this thing?

[Cranky_Doodle]

Saw this blade at a friends house, apperantly it was some DYI project they made from a leaf spring from a truck.
The edge is 28cm about 1/2 inch thick long and the thing weighs about 2Kg.

so what I'm curious about, is this style of blade a thing or just some homebrew junk?
it seems way too heavy to be practical to me, and thick, but supposedly it's nice for splitting smaller pieces.

on the bright side, I doubt any human can break this thing.
so maybe like a dedicated batoning knive?
Edit:
Forgot to attatch the image

https://ibb.co/y4Zfrdx

 

[KentuckyBlackBird]

Lawnmower blade.

 

[Blue Sky]

One-half inch sounds much too thick for a lawn mower blade? More like a leaf spring actually, but unless they had a forge I have to wonder how they got it flat. Random flat steel bar then? Don’t see much purpose to it other than a froe.

 

[rjdankert]

is this style of blade a thing

supposedly it's nice for splitting smaller pieces.

FWIW:

Bob

 

[Cranky_Doodle]

now that you mention the Bamboo Knife, I think it's vaguely similar to a Blade called "Nata", kinda like a japanese machete, just a very crude and thick/heavy one

the first truck that I could think of was a Ford Transit, I googled it and it does have a straight piece in there
if they had a forge they propably would have made something better with that steel.

I know that some knives are made from spring steel, then wouldn't a truck spring actually be a great source for material if you're starting out with forging and making knives?
or is there some difference between the type of spring steels that are more or less suitable for knives?

 

[kvaughn]

IIRC the khukris made by Himalayan Imports of this forum are from Mercedes Benz truck springs.
The one I have is great.
Someone may have more info on this.

 

[eveled]

One-half inch sounds much too thick for a lawn mower blade? More like a leaf spring actually, but unless they had a forge I have to wonder how they got it flat. Random flat steel bar then? Don’t see much purpose to it other than a froe.

Old walk behind Gravely tractors had a mower deck that uses 1/2” thick blades.

 

[Blue Sky]

That’s interesting, could be then.

 

[The Zieg]

My tractor PTO mower has two very thick swinging blades, also with holes IIRC. I can measure them sometime.

Zieg

 

[FortyTwoBlades]

Yes, if I had to hazard a guess it's a "splitting knife" improvised from an agricultural/industrial blade of some kind. Not manufactured as such.

 

[Cranky_Doodle]

little update(not that anyone should really care)

they didn't really need it so I asked if I could have it, took it home and came up with a design that could work.
unfortunately I don't have a forge or really space to build one, but I'll try do make something of it with "subtractive manufacturing"

supposedly it is actually from a leaf spring from some RV, they couldn't tell me the model tho, but the hole is from where the springs where bolted together in the center, it has a slight curve to it, but only about 1mm over the entire length
some preliminary hardness tests suggest it may be in the region of 55-60HRC, slightly harder than a wood rasp, certainly hard enough to cut copper, also capable of cutting machine screws with barely a nick in the edge, like you can actually see the cutting marks on the bolt, but it slightly bent/rolled the edge and didn't chip, which was the main concern I had.

it is barely soft enough to be drilled, but with lots of cutting oil(I'm using Ballistol ProTec) and going slow, and had to resharpen the drill bits 1-2 time for each hole I could get the holes in there.
tapping was kind of a nightmare, the first one went in ok, the 2th one only got like half way in and was really "sticky" and kinda weird, turns out the tap went dull, so I had to "sharpen" the tap to go all the way, got the 3rd one in just a few turns and called it good enough, since it also happened with the M12 tap for the big hole too i assume it's just kinda hard steel.

so now I'm just cutting filing and grinding to get the blade profile I want, just removing material to get the tip to the right shape removed about 200-300 gramms of steel, but getting the bevel to where I want will remove approximately 300-500 gramms just on the tip, it's already a noticable difference and feels much lighter now.
really looking forward to getting this finished, altho it's kind of a hassle since I can only work on it in my apartment and can't be too loud or really do much with an angle grinder.

I plan on making the bevel steeper as it goes towards the handle, mainly to keep that section as strong as possible, but also so you can still use it as a splitting knive.
I kinda wanna put a longer handle on it, but I don't have a drill bit long enough for that.

 

[Blue Sky]

Wow, you’ve put a lot of work into that. Surprised it’s so hard, I would have guessed a spring temper to be lower than 55+. By all means, keep posting this one, I for one enjoy the work-in-progress project threads.

 

[catspa]

Late 80s GM 1-tons had a 9 leaf stack that the top one was a curved overload and the bottom one was a double-thick short. Might have been one of those.

Dunno diddly squat about Ford or Dodge springs, but I can assure you that redneck boys fab up some weird shiite in the farm shop in the winter.

Parker

 

[Cranky_Doodle]

Thank you for your feedback

I tried making a jig to guide a makeshift drill straight trough the piece of wood, but it came out at a bit of an angle.
while looking trough my stuff to build the jig I found some 4mm poplar plywood sheets. I figured I could just glue a bunch of layers together and leave space for the holes.
the wood seems to be soft, very, very soft, so it's more of a proof of concept type of deal before I invest in anything better
nice thing about the soft wood is that I can use a utility knife to cut it to size

I was pretty skeptical if it would hold, but after some practice swings it "seems" to be fine and it's just long enough so you can put both hands on it if you want to, but mainly I want the flexibility to hold it with a bit more "leverage"
alto it might end up to be a 2 handed affair even after removing all that weight

after filing for like 2 hours I only got about 1/3 of the bevel done at the tip, didn't even start with the rest of the blade, and it feels like the files are getting dull
might see if I can visit my mate on the weekend to remove the bulk of the material with an angle grinder or something

 

[catspa]

Yah, power tools will come in handy on such a project.

A little piece of angle iron cut perfectly square is what I often use for a perpendicular drill bit guide out in the field. Sometimes I’ll clamp it down if I’m drilling in an awkward position. My buddy has one with a piece of 1/4” plate welded on the bottom, with screw holes so he can fasten it in place on a vertical or overhead surface.

Parker

 

[Cranky_Doodle]

I'll rather explore the "easy" options before I invest more time and energy in a failed attempt.

short handle is the the old one which is solid wood(no idea what, just some scrap I found) where I managed to drill the holes somewhat straight and the drill bit actually managed to go half way trough so they meet in the middle
the longer one is the aforementioned plywood, the length is just long enough for two hands, the glue joints seem to be ok, but i don't know how well the layers of the plywood sheets adhere to each other
I kinda like the shape of the 2th one, but I am still learning.

on an other note
do you think 3D printing would be a feasible solution for the handle?
or would it just snap?

on a side note, I Included the "progress" of the edge, that's kind of at the angle I would shape the edge at around the tip and the "belly" at the front, and then go shallower, transitioning to the old angle and even steeper near the hilt, again, for durability and so i don't grind in to the hole for the threads and still have enough meat to go up in size if necessary
and according to my calculations I barely got 1/5th of the material removed(at the tip), so it will extend at least twice as far towards the spine
gonna put it on hold til the weekend arrives, if I can squeeze working on that project it in that is.
the primary bevel (I hope that's the correct terminology) would be at about 7° for each side, I don't know if that's shallow or steep, good or bad, but what ever the angle is now is way too chunky to really cut effectively, kind of supporting the suggestion from FortyTwoBlades of it being a splitting knife, but having tried it myself, why not use an axe or a hatchet? there where like 8 of them on the wall next to the thing

 

[catspa]

If you’re going to chop with it, I predict the plywood glue joint will last about 4 strikes. Batoning it should about double that number.

Glue and wood fibers have very different impact properties, and you’ve got more leverage with the longer handle.

Parker

 

[Cranky_Doodle]

that is a concern I am aware of, I have some alternatives in mind to compensate for that and worst case I can just go back to solid wood with a shorter handle
first I gotta finish the blade, then after the handle breaks I'll make a new one
but I am contemplating if I should make it with the layers shifted by 90, so instead of parallel to the blade edge, have the layers go perpendicular to the blade
or perhaps shifted 90° in the other direction so the layers all get compressed by the screws, could even clamp it much better that way

 

[catspa]

So plywood lamination is it’s own thing, and has it’s own set of engineering. I’m not an engineer, but I’ve done some laminating and replaced some failed laminations.

I might try orienting it 45 degrees diagonal to the blade axis. I can see a failure mode for both the short and long grain veneers if oriented parallel or perpendicular.

Around here they sell a lot of plywood with a very thin face veneer, I’d avoid laminating with that kind of product.

Parker

 

[Cranky_Doodle]

pretty sure the stuff I have is exactly the one you may be warning me about, but it's a proof of concept, so I'll take that risk
not sure if i can even make that blade in any way manageable with a single handed grip tho, even after removing a lot of material it feels like a rock tied to the end of a long stick

one solution I've been thinking of is to pretension the threaded rod with a steel pipe over them
the tension/compression going on should make it quite a bit more sturdy and the handle would just be more or less sitting on the rods making it in theory more durable
I'd drill a recess in the rear of the handle where the nut for the pipe would be with an extra plate fixing the handle to the blade itself

however, the more I'm "working" on the thing the more I'm considering to look for a blacksmith in the area so I can either cut the blade and hammer the remaining chunk to the length of a machete, or just go full medival and forge a bastard sword or a Messer. there's plenty of material still on the blade that this would certainly be withing the realm of possibilities.

I know of one black smith that used to live near my childhood village, but I don't know if they're still living there or in the trade.

edit:
speaking of swords...
what about a counterweight?
is that a thing?
would that make sense or even survive on a machete?

I do have a big chunk of lead out of molten ammo from my youth
so maybe some antimony in there making it a bit tougher