Frustration - Warp - Help!!

Fiddleback

Fiddleback

Knifemaker
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Knifemaker / Craftsman / Service Provider
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For the longest time I was making knives that were relatively short (4" blade). But with the addition of my Woodsman, I have enountered new challenges to my knifemaking. Namely, warp (ps. I use mainly 01 steel).

First I thought the warp was happening during heat treat. So, I upped my game and got a lot more sophisticated with my procedures. Still had warp. Then I noticed that the warp was happening before heat treat. Then, since I was obsessed, I noticed that after using my chop saw to cut the bar to length, I got warp in the dagblastit blank.

Problem is that I haven't found any way to really get it out. Even soft pre heat treat steel. Oh I can bend it this way and that and try to counter the warp, but its not straight, its just warped the other way.

I had thought it was that I was generating too much heat during the initial bevel grinding. But last night I was very careful and really never let the blade get past luke warm. (Took forever.) Maybe I was pushing too hard against the platten and bending the blade during grinding? But last night I really just barely held the knife on there and let the grinder do everything. (Took forever.)

So I have no idea how I'm causing the warp, and how to fix it. I'm about to just drop the Woodsman. I'm loosing half the blades I try. I was all set to make a chefs knife now that I can HT stainless steel. But I'm obviously not ready for an even longer thinner blade.

HELP!!

I've got that vise device with the three offset rods, but it just twists the edge while bending the spine.

How do you guys do this?
 
Andy, there could be stresses in the steel before you even touch it.
- Try a stress-relieving soak at 1200F for an hour before working it at all.
- Mitch
 
Another thing to be aware of is you can create the appearance of a warped blade if you are grinding a little uneveningly. Make sure you are taking off a equal amount of steel on both sides. Ask me how I know:)

I also used to grind way too much before HT. Leave a goodly amount of steel on the blade, and a lot of your problems with warping might go away. Good Luck, and I know you will figure it out.

Dave
 
So, Troop, you soak your blanks at 1200 for an hour before starting to work them? OK. I can try that. I have ss foil, and a Paragon furnace. Anyone else do this?

DS, I use dykem to on the edge, and mark stop lines on my blade before grinding, but you could be right. How did you ensure you're taking off equal amounts of steel from both sides?
 
Would it help to just heat treat the damn knives then grind the blade?
 
Fiddleback said:
Would it help to just heat treat the damn knives then grind the blade?
Click to expand...

Some people do this but:
-You eat belts like crazy
-You have to be much more careful about overheating...one sight of blue on the edge and its back to the oven.

I have had the EXACT same warps as you. I have one going on right now with a tiny folder blade. It just keeps going right no matter how many times I fix it. Its in the steel.

My suggestions:
-Grind em thick before HT
-Normalize before HT
-Most slight warps can be fixed with careful grinding. IE Tip warps 1/16" to the right? Grind the tip down until your centerline will cross the warp at its furthest point, then grind into the warp to that centerline.
 
David Schott said:
Some people do this but:
-You eat belts like crazy
-You have to be much more careful about overheating...one sight of blue on the edge and its back to the oven.

I have had the EXACT same warps as you. I have one going on right now with a tiny folder blade. It just keeps going right no matter how many times I fix it. Its in the steel.

My suggestions:
-Grind em thick before HT
-Normalize before HT
-Most slight warps can be fixed with careful grinding. IE Tip warps 1/16" to the right? Grind the tip down until your centerline will cross the warp at its furthest point, then grind into the warp to that centerline.
Click to expand...

This I can understand! I have fixed slight warps by grinding! And I have started leaving more and more steel before heat treat. I always normalize. Luckily, the warp seems to be happening before heat treat. This was the one thing I've learned in the last month that made me happy.

But its still frustrating. Should I re-anneal the steel after grinding? Before grinding? After each time I glance in the general direction of the steel?
 
I had a sgian dubh that for the life of me i could not keep the tip from warping, I just did what David Schott suggested and reground the tip to bring it back to center, you cant even tell it was ever warped now that the blade is finished. Just need to leave a little extra meat (which also helps keep warpage from turning into cracking)
 
Troop's suggestion is correct.If the steel has stresses in it when you get it then a 1200 F treatment will stress relieve the steel.
If you put stresses in it from grinding a 1200 F stress relief after grinding will help.
 
I've used the 1200F stress relief cycle to help fix a couple of blades. Worked like a charm. I had a piece of ATS34 that was warped prior to even grinding on, and for the life of me I couldn't get the thing straight. So I popped it in the oven at 1200F for an hour and when it cooled down, it straigtened out with hardly any effort at all.

At 1200, you'll discolor the steel a good bit, but you shouldn't have a strong need for foil unless you've ground the edges pretty thin to begin with. Of course, it will look a lot better if you use the foil.

--nathan
 
Ok then. 1200 degree soak it is!
 
I recently had this problem on a small O1 bowie I HTed. It appeared to warp even before the quench. I didn't understand that one. I tried to bend it straight but had the same problems as you experienced. After quench AND 2x temper, the slight warp was really bothering me so I put it in the vise with the 3 rods and over tightened it and it broke in half. Anyway, I didn't think PFG O1 would come with stresses in the steel but, I normalized twice and still had the damn warp. Report back on how the 1200 soak works Andy.
 
Troop said:
Andy, there could be stresses in the steel before you even touch it.
- Try a stress-relieving soak at 1200F for an hour before working it at all.
- Mitch
Click to expand...

Absolutely yes! Depending on the precise details of its creation, your steel source could be plagued with anisotropic stress/strain. That would certainly explain your problem.

On no account should you limit yourself to small knives for a reason like this. That's FAR too constraining for you, your talent, and your growing business.

I'm sure the more experienced smiths here can offer the assistance you need to get past this annoying point.

Plus ... I really love, yes LOVE, my Woodsman.:D:thumbup::thumbup:

P.S. I would imagine this problem is even more annoying for swordmakers, so I would also encourage you to contact some of the makers of truly long blades for that "little extra help."
 
1200 degree soak for an hour, and allow to air cool? Or do I just let it cool with the furnace? Or do I need to stuff them down into the vermiculite?
 
Thanks Troop. I've got the Paragon ramping to 1200 now with lots of blanks inside.
 
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