View Full Version : Edge Packing


rhrocker
07-04-2004, 10:48 AM
Myth or real? I've read two accounts, both from master smiths. One says it is actually refining the grain, the other says it's just smoothing the surface. Both agree that it's done at almost black heat, towards the end of the forging process. Any thoughts?

Kevin R. Cashen
07-04-2004, 11:45 AM
I would like to offer a third perspective since this is not what I say this is what virtualy all the science of metallurgy says as well as most of the the laws of physics. "edge packing"(the very name is ludicrous and impossible, since steel is an incompressable substance)as it is typically described by a few bladesmiths is simply impossible, the universe just does not work that way.

As opposed to my retyping a large ammount of information, I highly recommend reading the following from another forum:

Edge density thread (http://forums.swordforum.com/showthread.php?s=&threadid=12535)

This is the MOST persistant myth in all of bladesmithing and as a testiment to that I can say that I have linked to this more times than any other link.

fitzo
07-04-2004, 01:05 PM
Excellent thread at that link. Thanks, Kevin!

AwP
07-04-2004, 02:28 PM
Yup, I read that thread a while ago, good stuff there.

I still believe the packing myth comes from WI, where it's not a myth, and just carried over to steel by smiths who were used to WI. Then those smiths passed the technique on to newer smiths who've never used WI and work only in steel.

With WI packing pushes the fiberous inclusions around to make them point the same way, making it less likely for the ends of whatever tool (I've heard about it the most with chisels and punches, usually things that use the end as the tool, not the edge like knives) to split under heavy use. With steel there are no fibers, so "packing" doesn't really do anything to steel, although going through the motions of it basically works like normalizing with some surface smoothing going on at the same time.

I do this, I just don't call it packing, I call it "normalizing without being able to resist hitting it a little bit with a hammer just because it's hot". Hmm, I spose "packing" does flow off the tongue a little better then my name for it even though it's an inaccurate term, I guess that's why some people call it "finishing heat". ;)

rhrocker
07-04-2004, 02:40 PM
Here's my personal favorite, from Goddards book "The wonder of Knifemaking" (this is not his quote BTW, he doesn't go along with the term, nor do I, but this is good): The edge is packed by hammering it lightly to "jiggle" the carbides into alignment. Forging reduces the size of the carbides along the edge surface, while packing tightens the crystal structure so the molecules remain on the knife's edge longer". Now that should make everyone a believer :o)

Kevin R. Cashen
07-04-2004, 03:47 PM
The first time I glanced through Wayne's book I saw a section on "packing" and was initially dissappointed, until I read the section and saw that Wayne did a great job on trying to dispell some of the nonsense. I realy loved some of those quotes he had in there ;)

Quenchcrack
07-04-2004, 04:06 PM
Here's my personal favorite, from Goddards book "The wonder of Knifemaking" (this is not his quote BTW, he doesn't go along with the term, nor do I, but this is good): The edge is packed by hammering it lightly to "jiggle" the carbides into alignment. Forging reduces the size of the carbides along the edge surface, while packing tightens the crystal structure so the molecules remain on the knife's edge longer". Now that should make everyone a believer :o)

That is a classic. I agree with the majority opinion here, edge packing of steel is simply a violation of the laws of physics. Inter-atomic distances cannot be changed by forging. Additionally, there are no molecules in a metal; metals form metallic bonds unique to metals resulting in crystals. Molecules are formed by ionic and covalent bonding. However, forging might indeed reduce the size of the carbides but I doubt jiggling has much effect.