Help, I'm warping!

[ErnieB]

Hello Everyone,
Working on my first blade here. Its a small version of the standard drop-tip full tang hunter. It is approx. 5-1/2" OAL w/ a 2-1/2" blade. It is out of a new piece of precision ground 1/8" x 1" annealed O-1. Since I don't have my forge hooked up yet, I'm making it using the stock removal method.

Everything was going fine until I was making a few touch-ups this evening and getting ready to harden, quench and temper. Just as I was finishing up for the day, I was looking at the knife as I seem to do every minute or so, and I noticed that the knife is starting to warp just at the point where the blade ends and the tang begins. (ie: if you lay it on its right side, it bows up in the middle.) I know for certain it had just happened because, as I said, I am constantly looking at it as I'm working on it. Throughout the process up until now, each time I've had it on the grinder, I've faithfully stuck it in the water bucket as soon as it gets hot to the fingers, etc., so I don't know what happened. I've never had it hot otherwise, except whatever amount of heat is generated with files & sandpaper.

Could someone help me out with this problem? I was so proud of myself up until now - I even had it by Bill Moran's shop yesterday and got his blessing! However, I can't wait until I get a chance to see Bill again to ask for his help so I'm asking you guys so maybe I can get a little sleep sometime soon. I hope I haven't ruined it...

Thanks guys,
Ernie B
Maryland

[TikTock]

Did you ever do any hard sawing with a hacksaw or sawzall, or any hard filing? If you had too much leverage, its easy to bend annealed steel. Luckily, you caught it pre-heat treat and most likely can bend it back, though let someone else here explain that since I am not sure. Ive had slight bends as you describe and all were due to my clamping it at a weird angle too hard or heavy sawing or even hard pressure by a drill press with not enough support near the drill point. Post us a pic! How warped is it? 1mm? 5mm>?

[AUBE]

what tiktock said was the first to come to my mind too. ive also applied too much pressure while grinding and bent it by force on rare occasions.

another thing it may be is the blade isnt really warped but you have just ground more material off one side of the blade than the other? this would cause it to rock as if it was warped.

if its not from generated heat it would have to be from mechanical lateral force.

the only other thing i could think of is uneven stress in the steel bar itself...which i havent ran into in precision ground stock yet.

and yes if it is pre-heat treat you can bend it back easily enough. use an arbor press or a vice with something like a wooden dowel on the high point of the bend...then slowly apply pressure checking every so often until it is straight

[jdm61]

accoeding to Ed and others I have talked to and read, a lot of warping is cause by uneven heat stress. Life will get easier when you get your forge. My fist batch that I quenched warped and twisted a bit. The subsequent couple a batches have been near perfect because I normalize at least 3 times between rough grinding and quenching. I had a couple of warped O1 blades snap during an attempt to straighten and they had BIG grain, so with O1, I notmalize 4 times and temper at 475-500. Those suckers turn blue, but no brittle blades in the last 2 batches and no warping. Edge seems nice and hard too. I chopped throught an old dry 2 x 4 with no edge deformation on a big O1 test blade with just a basic crude sharpening jub on a 220 grit belt. Bottom line is thermal cycling is all that it is cracked up to be. Good luck and keep destroying perfectly good steel. lol
Joe

[ErnieB]

Thanks guys,
The only handsawing was when I drilled some holes around the outline of the pattern and then sawed the excess off with a hacksaw. I also gave a lot of thought to the uneven thickness of the metal do to my inexperience in using my new Grizzly, but it really does look warped instead of excess metal anywhere. Thanks for the info. I'll look it over again tomorrow with a rested up set of eyes and re-evaluate the situation.

I know this is a hobby in which there will be lots of mess-ups and failures, but this was really a slap in the face as I really, really want to get good at making knives and and here I am screwing up my very first one! Making good knives is something I've wanted to be able to do since childhood and now at 47 yrs. old, I guess I feel I need to learn an awful lot in a much shorter period of time. I promised Bill Moran yesterday that I would go to his school and that is the next big expenditure I have planned. He has always told me I'll learn in 2 weeks what it took him 20 yrs. to figure out so I can't wait to get the funds together to go.

Thanks for your help,
Ernie B.
from Maryland

[TikTock]

Dont worry, its not a lost cause. You will straighten it. Honestly, there will hardly ever be a knife that goes together like butter from beginning to end. Each is a living, breathing, changing thing. It wont be the last! Just wait until you make what you consider your best blade yet, and it cracks half way to the spine during quench....Also, get some good digital calipers. You'd know right now if it was misground or warped just by measuring. Perhaps you can bend it back or if its just the tang, make it a tapered tang and just grind some more!

[AUBE]

Originally Posted by ErnieB

really a slap in the face as I really, really want to get good at making knives and and here I am screwing up my very first one!

lol...i messed up my first few dozen..and i mean bad. ive been doing this for awhile now (parttime) and i still mess them up. so dont feel bad, it happens..and this one sounds savable to me too.

[aiiifish]

Since this blade is prehardened all is good. Stick the bent part in your bench vise and slowly bring the jaws together to flatten the blade. Check it with a metal ruler edge to make sure its straight(the edge of the PG steel bar will work too)

then normalize the blade. If it curves back it shouldnt curve as bad as it was the first time. Back in the vice and do it again. keep doing this untill it is stress reliveved and doesnt curve the normalize twice more. (try to keep from doing it an excessive number of times)

Then harden the blade.

If youve done this right then you shouldnt have any curve after quench. Ocationaly you will get some warp after HT even when you thought you got every thing right. Jerome Anders showed me how to straighten it without too much problem. I find it only works on edge quenched blades.

Put the blade in your bench vise just past the bend. Making sure you protect the hardened edge start heating the spine like your drawing it back. While your heating the blade spine (make sure you heat evenly on both sides) pull the bend just past straight using the tang. When the spine gets a nice blue color stop adding heat, keep it pulled just past straight then pour water on the spine. If you did it right you will feel the blade sing or vibrate a little and you can release the tang. Your blade should be very near straight. Make sure you dont let the heat get to the edge though. That will cause some problems with performance.

Hope this helps

[AwP]

My understanding is that grinding can cause strain in the blade just like forging, just not as bad as forging. I'd probably straighten and normalize like aiiifish reccomends.

[ErnieB]

Thanks again everybody. I actually did the vise trick before I had a chance to read the late response that came in and it did seem to help. Also, as some mentioned earlier, I touched up what I guess were some thick spots that I'd missed before and that helped to. We just may salvage this blade yet!.

Ernie B.
from Maryland