blade bending while forging and general process questions..

R

radnur22

Joined
May 27, 2007
Messages
12
When forging out the bevel/belly of bigger blades, WIP around 11", the distal end keeps bending up. I tried forging the blade with the opposite bend, but the distal end keeps bending up and I had to forge it back to straight after each heat with the belly/bevel and then address and twisting of the edge. Should I not have even worried about forging the blade with the opposite bend initially and just straighten as I go? My order of forging goes like this, hot cut bar to length, forge rough handle, forge down top of spine towards tip, draw both ends out, forge edge working from spine down to the edge, one side, flip and then the other side, work my way down to the tip, edge thicker than a nickle, dress up the edge to around dime-nickle thickness. BTW, I am using 1/4" x 1 1/2" 5160

BTW..also posted on knifedog
 
I'm far from an expert or even very experianced, but the banana bend from forging the bevels is a result of spreading the steel out when drawing it down. Go most of the way, then take the bar and smack its spine against the anvil to straighten it. Then go back to straighten up the bevels.

Give a read through $50 Knife shop, he touches on this as well. Also I expect some more metal mashers to chime in.


-Xander
 
You need a whomper. Get a 2"x4" or some other piece of wood and use it to whomp the blade back in shape. It will minimize your bending.
You can also try forging the tip down before you forge the bevels and distal taper. Then when the bevels are forged and the tip rises you end up more or less where you want to be.

Another tool I've been using on almost every blade is my leg vise. I have a pretty nice 6" that is mounted on a 3"x30" piece of pipe sitting on a 1/2" thick 24"x30" piece of steel. I can forge on it, twist stuff and straighten bends out of blades with it.
 
If I understand you correctly, the upward curvature is normal when you forge the edge. You did induce a reverse curve but it seems not quite enough. You have found that it can be just as effective to forge then straiten as you go. It sounds like you are doing it right. Like Brian mentioned get a swocker, just a piece of wood to bend it back but not distort the edge too much. Takes a lot of practice but it will make sense one of these days.
 
Sounds like you need to figgure out your preform. Goodards books show
It well. It looks almost like you forge your profile, then start forging your bevels on what looks like the spine. That will bring the cutting edge up and straighten the spine. If you do it right, there won't be to much to straighten back out, then the wood to help with the distortion. Good luck
 
Brian Ayres said:
You need a whomper.
Click to expand...
A C Richards said:
Like Brian mentioned get a swocker
Click to expand...
radnur22 said:
time to get a whacker!!
Click to expand...
... And all this time I've been using a b'twammer...

You may want to try a different type of hammer. I sometimes use a "shop-made" hammer that I forged out of an old ball peen. It is kind of like a crosspeen with a slightly different dressing. The shape of the striking surface tends to move the metal perpendicular to the hammer face rather than spreading in all directions. It makes it easier to draw down or push up your bevels with less lateral expansion(which raises the tip).

IMG_0028-9.jpg

IMG_0134-5.jpg
 
Rick, do you have a hammer picture thread with all the colloquial names so we can keep them straight?
Love that hammer and picture.
 
I agree with Rick that a "Dog's Head" hammer is tops for drawing down the bevels. I also have a lignum Vitae "swacker" mallet that is used to straighten and flatten blades as needed.
 
I was shown another method than starting a reverse bend by Nick Wheeler. He starts with the bar forged to a point on the bottom edge and then as he forges that bottom edge thinner that bottom point slowly curves up to become a point near the top. Still used a big flat faced composite "wacker" to flatten bends and take excess curve out.
 
You must log in or register to reply here.
Back
Top