Broke my first blade

B

bennett

Joined
Sep 22, 2005
Messages
212
I broke my first blade tonight!:mad: It was a magnificent creation, too, if I says so myself. Beautiful dirk-style fighter made out of 1084, with a looooong clip point (that was to be sharpened) and a coffin handle(would have been made from gaboon ebony slabs and inlaid with some ivory I got at Blade 2004, nickel-silver pins...Damn!) and after the quench I could tell that the hamon was going to be a beaut once the thing was cleaned up. I cleaned off the remaining clay, and the oil, after queching, and was about to put the final finish on it and pop it into the oven. I noticed it had warped slightly, so I thought "oh, I'll just straighten that right out..." Idiot! I clamped it between wood pieces in my vise, and gave a slight tug and straightened the area near the handle, then reclamped near the tip. Gave a very slight tug, and "ping!".:barf: The tip snapped off in front of where I'd made the turnback on the clay coat. I think the handle straightened because the center, and spine area behind the clip, as well as the center of the handle, had been clay coated and were softer than the tip, the edge and the clip. Should straightening be done after tempering? Or is this the "secret" I just discovered the hard way?
 
Ouch

I do my best to straighten before quench :) barring that, it's amazing what can be done in the time between when the blade's been quenched and is fully cool :)
 
With 10XX steels it is best to get it in the temper oven pretty soon.Normalizing two or three times before quench is a good idea ,too.As soon as the blade comes out of the quench,and is still hot,you can do some straightening,but there is always some risk.Whatever you do,do it before the blade cools to room temp.Straightening tips of differentially hardened blades is the trickiest.Sounds like that blade will be a shorter bowie now.Anneal it,re-grind it,normalize it,and re-harden it.There is a lot to learn here.
 
Thanks for the feedback! I normalized it 3 times before coating and quenching it. Should I have tempered and tehn straightened, or checked it and done it before the blade cooled from the quench? And how can I prevent this from happening to coffin-handled beauty #2?:D
 
Most side to side warping occurs when on side of the blade cools faster than the other. Be sure that you put the blade in the quench straight, whether it is point or edge first.

Another cause of warping is that the grind is thicker on one side or the other. The cooling rate will be faster on the thinner side and cause the blade to pull that way.

A blade that has to thin of an edge will also warp from the thin section cooling faster than the spine. Leave it a little thicker on the edge and make sure both sides are even before the quench and it should turn out OK.
 
Thanks oljoe! I think you may have hit on the cause of the warpage, actually. The edge was a lot thinner than the edge on the other knives I've made, and I haven't had one warp as of yet. I double-checked the grind to make sure that both sides were even before quenching, however when submerging in the quench, I tried to hold it spine-up with the tip and edge submerged for 5 to 10 seconds, but I lost my grip because my oversized puppy chose that moment to try to get some attention:mad: So in addition to having a thinner-than-usual edge, it also went into the quench faster than my other blades have. I plan to try dirk # 2 starting tomorrow night, and I'll keep all of this great information in mind. Thanks a lot to everybody who posted:thumbup:
 
One thing that can help is checking for warpage after just a few seconds in the quench. After the blade gets below 900f or so it doesn't matter how long it takes to get to room temp. Quench for 5 seconds or so then check for warpage. If you have one the knife is still pretty easy to straighten at this point ... hot too.

If all else fails, I have done slight straightening right as I took a blade from the tempering oven.


Seth
 
I don't have too big a problem with warping now, but I still get one now an then, especialy with big wide blades.

The way I normaly do it is to temper once, straigten right out of the oven while hot. Next two cycles if it needs a little more I straigten a little more, and leve one temper where it didn't get tweeked.

One thing that has helped me quit breaking blades is the use of 1/2"-3/4" wood dowles. Three with holes drilled in the tops and brass rods so that they will stand up in the vise. Put the two on the side you want the blade to bend to, the center one on the bowed side and in center of the bend. Crank the vise down till it's straight, then flex just a little more to acount for spring back. The wood realy helps take the sharpness out of clamping the blade in a vise.
 
WILL52100 gives a good straightening technique!!! ,and oljoe gives the main causes of warping.Also make sure the clay coat is on securely and evenly thick.If it pops off one side (or cools faster on one side) it will warp bad.
 
Hey will52100, could you email me a photo of the arrangement you're talking about? I can't quite get an idea of how to make or setup what you are describing. That sounds like a very useful item to have around the shop.
 
Those long thin blades sure like to warp. Having too thin a cross section, as pointed out, is a gamble. Two things I would suggest; one is to coat the clay coated blade with borax as you bring the temperature up to critical. Do this early as the blade starts to take on heat. Second is to quench the entire blade and not just the tip and edge. You defeat the purpose of using clay if you only edge quench. You also have less chance of the blade warping if you submerge the entire blade. The quench is affecting the entire blade and not just the edge. More even stress, so to speak. The spine needs to lag behind the edge in cooling just a couple of seconds. The clay coating does this for you. .02cents Fred
 
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