drop-forge a knife? To achieve odd Xsection.

F

fnc

Joined
Nov 13, 2005
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I know a little about blacksmithing from books,
and a few experiments; but my knowledge of
different shop fabrication methods is almost
non-existent.

I used to see tools that said "drop-forged";
is drop-forging OK for making knives, and
drop-forging too expensive for the small maker?

It would be used to get the knife close to the
general shape and then do minor stock removal.

Why do it, if other methods are so much easier?
I am seeing old swords, bayonets, and even a few
knives with odd cross sections ("T", "Y",fullers) that
would require a lot of stock removal and special
grinders.

I assume a trip hammer or press would be needed
in addition to a forge, oven, grinder, etc.

Does anybody make knives/swords like this anymore.
 
Drop forging is for mass production, and as a whole is inferior to hand forging.
It uses two dies.The lower die is the anvil and the upper die is the hammer. The hammer (often weighing many tons) is "dropped" on the anvil with the red hot metal blank in the lower die. The high inertial impact squishes the metal to fill the entire void. There may be severe stresses,cracks,and voids in the final forged piece. Mostly it is used to mass produce tools like whenches,with simple shapes and small size. I have drop forged coins at a demonstration on forging (100 pound hammer and 200 pound anvil to forge 1/2" copper coins, 6' drop).
Stacy
 
would it be praticle to have a die that is a steep v type shape to get some what of a bevel?

meh after i typed it out i realized the amout of work it is probably just as easy to just hammer it out by hand right?
-matt
 
SR_matt said:
would it be praticle to have a die that is a steep v type shape to get some what of a bevel?

meh after i typed it out i realized the amout of work it is probably just as easy to just hammer it out by hand right?
-matt
Click to expand...

You guys are acquainting me with some realities.
Drop forging is out,

Is there a more smithy way to do it, that preserves uniformity?

I imagine this as the first operation on a billet.

The billet locked to the anvil, with the spine (back) up,
edge side flush down against the anvil.

Using a big sacrificial chunk of steel as a heater bar,
touch it to a section of the spine.
Now, (part of) the spine side is dull red for easy shaping and the
and the other (edge) side cool enough not to deform too much,
facing down, against the anvil.

A fuller-tool with an inside-Y shape sliding
(and being hammered) across the spine-back.
The fuller-tool would work like a slip-form for concrete.

Also, the fuller-tool could have a shallow-Y and
progressively change shape toward a deeper-Y.

Does the above sound realistic?

Other option would be to buy stock that is a T or Y
already, but I think the top of the T would be too wide.

Another option, a custom order: big bucks.
 
forging steels really aren't all that expensive, I think you're making a mountain out of a molehill. Don't worry I've been known to do the same thing:D
 
Nothing in your profile,so I don't know what abilities you have,but here is some more info.

Lets say you want to make a bayonetor knife with a "T" shaped spine. You could mill out more than half the steel in a square bar, or forge it to shape. A smith would do one of two things.
1) If the "T" was not too large,he would use a swage block (or make a "V" slit hardie tool), and use it to hold the hot steel while upsetting the spine to a wider shape. That way he would form the bevel and the "T" at the same time.
2) If the "T" was large,or a "Y" he would forge the bar into a triangle, and hot chisel the spine to open a groove. Then ,using the swage, he would forge open the groove into a "T" or "Y".

A modern smith would use a power hammer or press to do this with a custom swage block die. The cost would be somewhat high to make the die, so it would require multiple blades to recover costs.

Your idea of cooling the edge and upsetting the spine is probably what I would do for a single blade.Three ways come to mind:
1) Have a cookie sheet with about 1/4" of water in it. Set the edge in the water for a second and it will drop the temp in the edge, move the piece to the anvil and upset the spine. It will still require a lot of clean up forging when doing the bevels.
2)You could make a simple swaging "V"tool for the hardie hole from a 3X3X3" block of steel with a "V" sawn into the top. Weld a square tang to the bottom that fits your hardie hole. Using this you could do the job fast. Again, multiple blades would recover the cost and time of making the tool.
3) What I myself would try for one blade is clamping the hot steel in a post vise,or caulking vise, and upsetting the spine.This should be the best option, since you can set the bevels first and use the vise shoulders to shape the "T" spine.

Hope this helps - Stacy
 
mrstenoien said:
forging steels really aren't all that expensive, I think you're making a mountain out of a molehill. Don't worry I've been known to do the same thing:D
Click to expand...

I do not remember exact prices for ordinary flat stock;
I do remember they seemed very reasonable, no worries.

However, I assumed a special order of thick-spine stock would be
expensive and I would have to buy a lot.
I got this impression on a resent thread on this forum.

Am I missing something? Does someone have an example.
 
my first piece of steel was a piece of 5160 2'x2"x.446" from a local custom spring shop, it was 20$ it was way too thick but it was the thinnest piece they had, check em out in your area
 
If a 4x4 shop or custom spring shop doesn't have the bit. try a transport engineer workshop or heavy truck repair workshop. some trucks have leaf springs with individual leaves up to .75" thick.

MTM rund the courner from where i worked had truck trailors and lowrider trailers under construction stacked in their yard at times. the spring packs from the footpath looked up to a foot thick on the heavy transport flatbeds.
 
bladsmth said:
Nothing in your profile,so I don't know what abilities you have,but here is some more info.
...
3) What I myself would try for one blade is clamping the hot steel in a post vise,or caulking vise, and upsetting the spine.This should be the best option, since you can set the bevels first and use the vise shoulders to shape the "T" spine.

Hope this helps - Stacy
Click to expand...

Thanks for more examples. I mis-used the term "fuller-tool" when I was
thinking of a combination chisel-and-swage-tool.
It would be difficult to make.

I like the expedient idea of using a post vise.
 
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