First knife shape object

[Dls1990]

Hey everyone just got my forge up and running and forged my first knife shaped object. I started with a leaf spring and did all the forging by hand. I have read on here before that some leaf springs are not hardenable so I tested a small piece I cut off by heating to non magnetic and quenching in vegetable oil. One swing of the hammer while in the vise and the corner snapped off. Anyways heres some photos, the spine as of right now is about a 1/4" and the edge is about 1/16". I still have to heat treat and grind but it got late and I didnt want to xxxx off the neighbors. Please be honest with any criticism on what you guys see it's my first anything that I've forged. I will post more photos after heat treat, grinding and the handle is finished.

[MC Hammer]

Having only made my first knife a month or so ago I can tell you that the easy part is done   Normalizing, quenching, tempering and grinding is where all the work is.  I think that if this is the first thing you've ever forged that you did pretty well.  I never recommend starting forging with knife making because all the skills I've learned since starting forging were needed by me when I made my first knife.  

I'd recommend grinding all the scale off and looking for cracks before you quench it just to see how you did.  One rookie mistake is hammering high carbon steel when it's far too cool (red heat or below) which can cause stress fractures.  Grinding will also allow you to correct the blade shape.  Don't grind a right angle where the tang meets the blade as that will cause a stress area.  Leave your blade thickish when quenching as this will help your warping.  

Finish the knife and show us pictures.  Above all, be proud of what you did.  How many people in your neighborhood forged a metal blade this week?  Guaranteed probably zero.  Don't get discouraged by the process and keep going with it.  I would recommend making some hooks and things for your shop just to practice hammer control and drawing out and other base skills.  

 

[Dls1990]

Thanks for your thoughts and advice, I actually am a roofer and pretty much do all historical work like slate and copper so I've been making my own copper soldering iron heads as well as buying and restoring old antique heads for years so I have some basic skills on shaping and drawling out hunks of metal. of course copper is a way easier and more malleable thing to work with and heating up on my acetylene torch is totally different then a forge with hot steel. I will try to start finishing the blade tonight if I get off work early enough and I will post some pictures. Thanks again.

[Jim L.]

I would recomend that you bring the blade to near finish grind and sanding before quench.  Leave some meat on the cutting edge. This allows for better thermal retention and less chance for warpage.

This sounds like a bunch of whodoo; finf magnetic north and align the blade N/S at quench. 

A very good start, Sir.

[sfeile]

3 hours ago, Jim L. said:

This sounds like a bunch of whodoo; finf magnetic north and align the blade N/S at quench. 

I hope that was just a joke. There is no reason to point a blade to magnetic north when quenching other than maybe it is the best lighting option when heating or the way your shop set up happens to face by coincidence. There is no scientific reason that will alter the blade due to what direction it is pointed on a compass.

[Marc1]

Magnetic North pointing is a must, and so is invoking the help of Vulcan 3 times whilst turning left. Pinch of salt over your shoulder is optional 

[Irondragon Forge ClayWorks]

I just hold my breath.

[Jim L.]

On 1/5/2019 at 3:08 PM, sfeile said:

I hope that was just a joke. There is no reason to point a blade to magnetic north when quenching other than maybe it is the best lighting option when heating or the way your shop set up happens to face by coincidence. There is no scientific reason that will alter the blade due to what direction it is pointed on a compass.

Sorry, nope. Not a joke. The explanation given was that ferrous metals heated to non-magnetic will seek out magnetic north as they cool. What ever the reason it seems to work. Believe it, or don't. I've had little to no warpage since beginning the practice. 

Science can explain everything, but that doesn't mean we understand what we are told.....

[JHCC]

7 minutes ago, Jim L. said:

I've had little to no warpage since beginning the practice. 

Correlation does not equal causation. It's much more likely you've been having little to no warpage because you're being more careful about quenching at the right angle relative to the quenchant than because you're seeing any effect from a North-South alignment. You've also probably gotten better at judging the evenness of your blade's heat before quenching, so the transition from austenite to martensite is happening more evenly and with less unbalanced stress.
 

[Buzzkill]

Really?   So, if you're quenching vertically should the spine or cutting edge be towards magnetic north?  How far off of magnetic north does your alignment have to be for the blade to be affected?   Can you feel or observe any magnetic pull on a finished blade towards magnetic north?  If not, how can an imperceptible amount of force be enough to warp a blade?

The list of refuting evidence goes on and on here.   I suspect it was started by some old bladesmith pulling someone's leg who didn't realize it was a joke and then the tale grew legs of its own

[Jim L.]

If you flap your arms real hard, chances are you won't feel any lift (um, it's imperceptible for many reasons). The wings of a C-5 Galaxy transport must generate excess of 500,000 pounds of lift in order to become airborne. You can not "perceive" the reasons between the results with your senses. Ergo the heavier than air craft was concieved of by an oldtimer making a joke.

Do not discount an idea on merit of perception only. No, I can't tell you the molecular properties with certainty of a particular metal at a given thermal state. I can tell you that occurrence of warpage is greatly reduced using near identical angles in the same quench vessel and quenchant when in the northerly orientation versus 90° to that.

[Buzzkill]

No, you can't tell me that with any amount of certainty.  There are far too many variables to take into account to conclude that quench tank orientation is the determining factor in quench warping.  A slight difference (less than a millimeter) grinding on one side compared to the other is enough to create unequal forces on the steel as it cools rapidly.  Failure to properly perform normalization cycles can leave uneven stress in the piece that will become evident upon quenching. Slight side to side movement of the piece during the quench can exert more force on one side than the other.   It is very difficult for a backyard smith to run comparative analysis with the only changing variable being the orientation of the quench tank in relation to magnetic north.  Your perception is that there is a difference, but hard evidence is a different matter.

We *can* scientifically explain the mechanisms by which heavier than air craft gain enough lift to get off the ground.  We can reliably and repeatedly demonstrate this phenomenon in a very predictable manner.  The same is not true of the "quench to magnetic north" myth.

Having said all that, if you believe it makes a difference then continue with what works for you.   Just don't expect other people whose experience is different from yours to accept your beliefs/perceptions as fact without solid evidence to back it up.

[Steve Sells]

I don't know where to start,  posting this in response to a noob that is trying to get serious information is just plain unacceptable . I am surprised you left out the standing on the left foot part.

FYI  human arms give as much up- lift when flapping as they do down force. so anything that may exist balances out, and gravity has more pull on the steel than magnetic north, so using your logic states it should straighten it out rather than allow a warp.

[JHCC]

Not to mention the fact that the large masses of ferrous metals typically found in blacksmith shops create variations in the local magnetic field.

1 hour ago, Jim L. said:

No, I can't tell you the molecular properties with certainty of a particular metal at a given thermal state.

Ah, but we can. Above the A₁ temperature, steel is non-magnetic. Below, it's not. At quenching, the FCC austenite transforms into FCT martensite at slightly below the speed of sound, exerting enormous force on the steel -- much more force, in fact, than any minor influence of the earth's magnetic field.

[Glenn]

Jim L, Please take this into consideration the OP is new and asking for real advice.

 

[Jim L.]

You are correct in that with in 99% certainty, using science [wing loading (square surface ÷ weight = weight/ in. sq.), air velocity, air foil shape (Bernoulli's laws and the venturi principle) yada, yada, yada] that "X" aircraft will fly.

I merely stated, using perception only the eye cannot explain scientific fact.

That said, feathers were not meant to be ruffled, nor undergarments bunched, much less ill-spirited and/or sarcastic comments meant to be inspired.

I can only state the fact that I have witnessed this phenomenon and admit that I cannot offer a scientific explanation as to why it occurs to my or anyone else's satisfaction. There are as stated and conceded, too many variables. My ignorance as to how it happens isn't proof, scientific or other wise that it doesn't. 

[Buzzkill]

While I hesitate to give any more life to this conversation, I am curious about your observations.  When you quenched with the blades roughly 90 degrees from magnetic north, did you happen to notice if the blades that did warp all warped to the same side even if the spine and cutting edges were in reversed orientations on subsequent blades?   After all, if the earth's magnetic field could exert enough force to warp a blade, then there should be consistency in the direction of the warps.  

Just for reference sake though, gravity exerts far more force on a blade than the earth's magnetic field.   It's far more likely that a blade would bend or bow slightly between the forge and quench tank due to gravity and the orientation of the blade in relation to the ground (i.e. the flat of the blade parallel with the ground rather than perpendicular to it) than due to the magnetic field of the earth.

[pnut]

None of it matters since the Earth is flat!!!   JK

Jokes aside people just beginning to learn the craft of which I count myself as a complete novice don't need spurious info muddying the waters. The learning curve is steep enough without someone propagating myths and old wives tales.

Thanks to everyone for quickly putting this fairytale to rest. There's much to be said for peer reviewed sites such as this

   Pnut (Mike)

[ThomasPowers]

Books tend to be a bit better than the net as the cost to generate one is grater and so filters out a lot of the clueless.

[Steve Sells]

Simple to prove if gravity pulls more on steel than the magnetic field of the planet:  Just drop a knife, and observe - does it head north or down when you let go? that same force is acting on it as you quench, after all quenching does not shield it from these effects nor magnify one over the other, but people still want to believe......

[Anachronist58]

Very interesting. Many quite intelligent people deploy abductive reasoning as a mode of pragmatic operation.

That is why the empirical method is so important. Our magnificent brains tend to leap far ahead of what has been tediously worked out via  scientific rigor.

The geomagnetic flux is in constant turmoil, at the mercy of even the common metallic objects that surround our modern lives. Indeed, a weak influence.

Robert Taylor

[ThomasPowers]

If you ever get a chance; look at a geomagnetic map of Magnet Cove Arkansas;  In my geophysics class we had to use the rate of change in the flux lines to determine how deep the deposit was that was causing the anomaly.  The class as a whole got 2 different answers: one was a ground surface level; the other was 70' above the surface...

[Frosty]

The easiest to find proof of the magnetic north at quench question is to find out which direction commercial knife makers point the blades when quenching or tempering. Heck, ask a commercial heat treater. 

In the early days of the craft folk needed a marketing "hook" that made their product more desirable than another bladesmith's. Look at current day Japanese bladesmiths, every darned one has a: secret ore deposit, secret charcoaling method and material, special bend in a special creek for their quench water.  

Perhaps in the earliest days "everybody knew" it was a fact but that was then, this is now. 

Frosty The Lucky.

[ThomasPowers]

(FNORD Nobody tell Frosty the secret, he has not been initiated into the craft, not even at the illustrious grand accepted puissant burnt fingers level. \FNORD)

[Steve Sells]

<thought> Frosty wont remember even if we told him,  after the birch incident </thouight>