need help. triangular blade

O

oldwolf

Joined
Dec 29, 2002
Messages
617
I need to make a trench type blade which is triangular shape. It's a first for me so any help and tips would be greatly appreciated . Seems like starting with a rod would be most efficient, but how do I keep equal sides?
 
In the shop talk category of the forum there are several "sticky" articles which are intended to serve as beginner/novice tutorials, and most of them have sufficient information. If you haven't read any of those or are enirely new to bladesmithing I suggest checking them out. Also, a few questions that might need answered so that you can recieve even more help and advice to help prevent issues...

Do you know what type of steel you want to use? Will this be a single or double edged blade? What are the basic dimensions you want for the blank? Do you have an angle/handheld grinder or belt sander?
 
Ninja,

I think old wolf is talking about dagger with a triangular cross section, or a three edged blade if you will.
I don't have any experience with that kind of grind but doubt if there will be much info in the newby stickiness.
I'm sure someone here has done one though and will chime in.

Greg
 
Whoa Ninja. He is only asking a simple question. If you don't know the answer, sit back and let the folks who do post.


Oldwolf,
Forging a triangle blade is a bit of a trick, as an edge is always down when hitting a flat. You need to make a 60 degree "V" shape hardy block. The "V" only needs to be about 1/4" deep.
Start by forging a round bar down to a long taper. Take it right up to a point. Set the taper on the "V" and start an edge. Draw it straight as you work down to the point. Turn 120 degrees to bring a flat upward, and do another draw. Then turn and work the last flat. Continue to clean them up as you get things even and straight. Take your time working each heat over about 3-4".
Do all the rest on the grinder.

The alternative is to just forge the tapered rod and grind in the flats.
 
G. Shahan said:
I think old wolf is talking about dagger with a triangular cross section, or a three edged blade if you will.
Click to expand...

AH, ok. I understood it as being triangular from the side profile instead of the cross-section; so something like a Renaissance stiletto then. The design I was picturing in my head makes a LOT more practical sense now.
 
G. Shahan said:
Ninja,

I think old wolf is talking about dagger with a triangular cross section, or a three edged blade if you will.
I don't have any experience with that kind of grind but doubt if there will be much info in the newby stickiness.
I'm sure someone here has done one though and will chime in.

Greg
Click to expand...
Greg is correct. 3 sided stabbing blade. Just hoping for some grinding tips so I don't have to ruin too much steel to get one right.
 
I had this in mind when you asked the question.
ph-0.jpg


I've thought about it too.

If I were to machine it I would mount it on a milling machine, between centres, using a dividing, or indexing head.
You can google some photos of that.


If I had to replicate that on a grinder
I would make up something like this to hold the rod
Using a disc with a setscrew to hold the indexing disc to the rod.

Then I'd put it to the grinding belt at an angle

It's still going to be a lot of freehand on the long distal taper angle, but you could calculate the angle of that long taper and setup some clamps on your rest to help eyeball you in.

If you want to be really authentic, that blade has a slight hollow grind, be sure to keep that centered as well.


triagularblades.jpg
 
I had some thoughts on a blade like that.
My idea was to use a store bought triangular file as a starting point.

Edit: I don´t know about the law where you life but a trench knife like that woulde be VERY illegal to have over here.
Might want to look in to that.
 
What do you think about the thickness of the steel rod and who might have it. I would think the blade is about 1/4" at the guard so 1/4" rod?
I like Hengelo's idea of the triangular file. Just need one about 8 3/4" long. Whichever I will be grinding and not forging.
 
12345678910 said:
The no-no for us on that is the guard - it counts as a brass knuckle
Click to expand...
That´s what makes it illegal over here as well.
Even as a collector it is close to impossible to get a permit to have one of those US WW1 trenchknives.
 
I would work from 1/2" round stock, and end up with a minimum of 3/8" at the guard. It is simple math to trisect a round, so getting it even should be easy. Turn/file the tang down to a taper, leaving a shoulder at the ricasso so the guard sits against it.

Make a disk of cardboard, or something stiff, and drill a 1/4" hole in it. Trisect it (use six radii points) and cut along the flats. This can be slipped on the blade when working to check that the flats roughly line up.
 
bladsmth said:
I would work from 1/2" round stock, and end up with a minimum of 3/8" at the guard. It is simple math to trisect a round, so getting it even should be easy. Turn/file the tang down to a taper, leaving a shoulder at the ricasso so the guard sits against it.

Make a disk of cardboard, or something stiff, and drill a 1/4" hole in it. Trisect it (use six radii points) and cut along the flats. This can be slipped on the blade when working to check that the flats roughly line up.
Click to expand...
Great info Stacy. Thanks. About how I figured, but always smart to ask.
 
Hey Count, that jig you drew up looks exactly like the jig used to jewel (engine turn) rifle bolt bodies. A google image search should turn up results for it.


-Xander
 
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