Need advise - The Knife Network Forums : Knife Making Discussions

alexkuzn · #1 05-29-2006, 04:29 PM

I had some minor warpage after HT/tempering on my 1/4" thick O-1 blade. Final hardness was about 60 on Rockwell scale.
I tried to straighten it out with 1 ton arbor press but 1/4" steel was too much for it. I switch to a vise. Then I switched to vise and three steel rods. With that setup I could bend my blade while in a vise but it always returned to it's original shape.
Finnaly I applied too much pressure and it snapped.

I am thinking about welding a threaded rod to it and make a hidden tang knife. What do you think?

mete · #2 05-29-2006, 06:59 PM

Don't try to straighten a hardened blade at room temperature . Try it at the tempering temperature.

DiamondG Knives · #3 05-29-2006, 11:53 PM

OUCH!! Thats a tough lesson to learn the hard way!!!

Instead of welding a tang onto it which will present its own demons,(have to reheat treat the blade) Why not drill a hole in the tang, and use a collar and a pin? This will give a very good mechanical bond, as well as allowing you to have a moveable tang that allows several handle options.

Mabe folks will chime in and offer better solutions, just my $0.02.

Drop me an email if you have any questions mikegarner69@hotmail.com.

God Bless
Mike

Andrew Garrett · #4 05-30-2006, 12:13 AM

And that was such a nice grind job too... dang.

I say anneal it, weld on a stick tang, re-anneal it, and then re-do the HT. For that matter, just weld THAT tang back on, bring it too tempering temps, pound it back into being straight (or use that three rod trick), grind the welds clean, NORMALIZE it, ANNEAL it, then try the HT again. A satin finish on the welds that are exposed should mask them nicely.

Remember, At least 50% of making a knife is correcting mistakes and solving problems. ...at least it is for me.

alexkuzn · #5 05-30-2006, 01:04 AM

Quote:

Originally Posted by Andrew Garrett

Remember, At least 50% of making a knife is correcting mistakes and solving problems. ...at least it is for me.

I don't feel alone any more!

Josh O Mason · #6 05-30-2006, 09:43 AM

oh dude....thats a heartbreaker.

sorry man.

Andries Olivier · #7 05-30-2006, 01:58 PM

I'd say hang that one on the wall as a reminder on what NOT to do and start on a new one. With the amount of time and effort you will spend on trying to correct your mistake and still make an inferior product, you could just as well make a fresh one.

horseman1 · #8 05-30-2006, 11:59 PM

So, being a newbie forum I guess can ask this:

Could someone explain to me why Andrews solution (weld it back together and start over) is not a good solution? Alex did an awesome job on the blade, is it really that hard to fix?

If that beautiful blade was at my place, I'm pretty sure I could get her welded back up and lookin good in pretty short order.

You would really going to make it a wall hanger to remind yourself of what not to do?
If I did that with every thing I came up against I'd have a bunch of wall hangers and nothin else. Btw, I dont have any wall hangers and I have bunch of somethin else.

If someone could explain why Andrew's idea is not a good solution I would really appreciate it, because that is exactly what I would do. I'm obviously overlooking something!

Thanks,

Kurt

titaniumdoctor · #9 05-31-2006, 03:07 AM

Wow!! Funny you should post on this topic. I just did the same friggn' thing, except mine was a 12 inch piece of damascus. Snapped er' right in half!!! I ended up clamping it to a steel table and welded it back together, keeping away from the top and bottom of the visable tang. I can see a very slight crack line, but hopefully after fileworking and etching it will hide. If not, I'm looking at about a $600 mistake. Live and learn I guess. Sucks to be me.....and you!!

Good luck to ya, Jeremy

Jacktheknife · #10 05-31-2006, 11:27 AM

Alex,
One of the skinners I am working on was warped.
I just noticed it the other day.
One out of 26 ain't bad.
The steel was a $2.65, piece of 1095,
Don't know why it warped,
but I am learning.

J. Knife

NJStricker · #11 05-31-2006, 12:03 PM

Alex,

No one else has asked, so I will. . .do you have any ideas why the blade warped in the first place?

Andries Olivier · #12 06-05-2006, 04:41 PM

Quote:

Originally Posted by horseman1

So, being a newbie forum I guess can ask this:

Could someone explain to me why Andrews solution (weld it back together and start over) is not a good solution? Alex did an awesome job on the blade, is it really that hard to fix?

I guess if he is making the knife for himself it would be OK if he weld it together and complete the knife. If it is for a customer it is in my opinion not a good idea. The customer is paying for a well made knife, that's why he is buying a handcrafted knife and not a mass produced factory knife. (not that all factory knives are bad)

When you weld 2 pieces of steel together the heat of the welding causes carbonloss in the area of the weld, thus weakening the steel at the weld. That's why you often find welded parts breaking next to the weld.

If you consider the time it takes to "repair" the blade, ie. welding, flatgrinding, annealing and heat treatment, You could just as well grind a new blade in the same time. The fact that the blade is welded together increases the risk of warping again.

Warping could be caused by several factors such as the blade being burnt during grind, uneven grind, sideways movement in the oil during quenching etc.

Unfortunately a good knife doesn't only consist of a beautiful blade. It's the quality of the total package that makes the difference.

BTW. I have 3 blades hanging in my workshop. One cracked during HT and I wrote "PREHEAT OIL !" on it with a permanent marker. The other two will never be knives because of impatience on my side. The grindlines didn't turn out the way I wanted them and even after a million "last-minute" design changes I couldn't satisfy myself. Both are marked "BE PATIENT".

If you don't have the time to do it right, when will you get the time to do it over?

titaniumdoctor · #13 06-06-2006, 02:17 AM

Warpage is a fact of life my friends. Especially if the steel is oil hardening. When you take a piece of steel and go from non magnetic to oil quench in seconds, it's gonna warp. Thats just what it does. The longer the blade, the more it's gonna warp. I don't buy the "weakening at the weld" theory. If one knows what he's doing, a weld can be stronger than the existing steel. It's like silver soldering. Take two pieces of steel, silver solder them in a lap joint and pull it apart in a press. If done correctly, the steel will break, not the solder joint.
I surface grind all my blades to within .0005 before heat treat. All my blades go to professional heat treat. Air or oil harden. I have not had one come back without at least .002 worth of warpage in it. Shim it, and grind it flat. I learned a lesson, grind a hardened blade flat. Don't try to bend it. Good luck to all.

Jeremy