Need Tips for Forging Blades Straighter

[woodtick]

I need tips for hammering techniques that keeps a blade from getting such an upsweep when forging/thinning out the cutting edge.

[Woody]

Before beginning to forge the cutting edge thin, give the blade a concave bend toward the cutting edge, then as you forge the cutting edge thinner and the metal stretches, the blade will straighten out. You will have to expiriemnt with how much bend to give the blade to start with.

Woody

[Rantalin]

Do you mean an upsweep like a katana blade would have, or is the blade curling up along itself like rolling paper into a tube? Is it is the former, the only thing I've found for a single edged blade, like a knife, is to pre-bend it in the other direction. If you are forging a double edged blade, the best way is to hammer both sides of the blade equally to keep it straight.

If the blade is curling itself up, I can't really think of how to help you, maybe one of the more experienced smiths could help you out.

[HWooldridge]

Slightly OT but related to the topic:

A buddy of mine went to Japan on vacation a few years ago and was able to watch a traditional knifemaker at work. This smith primarily made kitchen knives for the public, some with a welded edge but most out of homogenous steel. He bought his steel normalized and cut out the blanks with a band saw. My friend did not know what type of steel but said the smith used the typical Japanese clay technique for coating the blade prior to quenching and he did not draw a temper. He bought the blade he watched the smith make and uses it daily in the kitchen. It is straight ground and holds an edge very well. Looks like a small chef's knife (maybe 5" blade) and has a temper line - plain wood handle scales with two rivets.

The interesting thing is that after the smith was done forging, he would heat the blade and curl it like a leaf in one direction, then straighten it, curl in the opposite way and straighten again. After this, it was tossed on the floor and allowed to cool before the hardening step. Although the language translation was poor, my friend said he understood the smith to say that this "stretched" the blade in each direction and helped keep it from warping in the quench.

Have any of you blade forgers heard of this technique?

[ThomasPowers]

I've never heard of the double curve technique. normalizing before heat treat is a common step to help avoid warping.

As for straightening a blade: you can actually heat it up turn it so the belly of the bend is up and straighten it by hitting downward on the *EDGE* you are not walloping it but pushing it back in place and correctly done does little to the edge that will need to be tweaked---you can even do it with a wooden mallet if you are afraid of messing up your blade.

This is a technique used by many bladesmiths and works very well though counter intuitive.

Thomas

[sandpile]

UP SWEEP on blades. You did not give us much info for the replys.-- We have to assume that you are working in the smaller sizes.

WOODY is right for the first stages of the drawing the metal down to start looking like a knife blade. After you have gotton your basic shape of the knife profiled and you are ready to start drawing the bevel down the sides.

Reach across the anvil and put about 20 to 28 degree forward or down drop in the blade. Do this just about an inch or so in front of what is called the riccasso. As you draw your bevel out this will work the bend back out of the blade.

THOMAS is right in the final stages of shaping the blade. you can straighten a small bow by turning your blade on its back and gently tapping the bow out of it. The spine has to be yellowish orange to start, letting the edge drop some heat before you do this and the back will still be a red, be real gentle with your leading edge. When you let the color run out of the edge it is tougher and will not mushroom so easily.

Another word to the wise always forge thick and grind thin--ALWAYS. You will have to normalize the blade a couple or three times and anneal it before you start your hardening procedure.

That will keep it from warping so bad.GRIN.

Good luck.

Chuck

[woodtick]

Thanks for the replies!
It's wondeful how everything gets nice and simple when it's explained to you, you saved me alot of head scratching.

sandpile; Yes I meant the small sizes, 4 1/2 inch hunting style blades. Whenever I tried forging down the bevels, the profile of the blade kept curving up too much at the tip for my liking.
Every time I tried to find the right wording for my original post I couldn' keep from confusing myself let alone keep the readers from getting confused. LOL :mrgreen:

On a sad note, the first blade I forged turned out with a broad blade with alot of curve to the profile and by fate or by accident had turned into a nice little beaver skinning knife. I was just doing some hot filing and finishing touches to it when I turned my back for just a few seconds with the air going in the forge!! It turned into the prettiest piece of slag that you ever saw! :roll:

[elkdoc]

For straightening or flattening on the short axis, nothing beats a good wooden mallet. They'll bend and apply pressure withouth marking the blade.