View Full Version : Newbie needs help
08-22-2010, 10:38 AM
I am grinding one of my first knives and as I was grinding I stopped several times to assess the blank. I noticed that the blank is slightly warped. Is this due to over heating while on the belt grinder? The stock is 1095.:15:
Thanks in advance,
08-22-2010, 11:12 AM
Possibly, but lets get a bit more info first...
What is the overall size of the blank? thickness, blade length, etc...
Is the blank already hardened and tempered?
Are you cooling periodically by dunking in water?
Do you have a pic of the blank with the warp?
08-22-2010, 11:29 AM
Sorry if I am not using the right vernacular, it came from Admiral steel as a a 72" piece of 2"X3/8" flat stock. I made my own design transfered it to a piece of this steel. It is/was going to be a Santuko kitchen knife where the blade is 7" and the overall legnth is 11.5". The blank is not hardened nor tempered and yes I am dipping it in water when I feel the metal get hot(I'm wearing gloves). No pix of the warp as I just noticed it and my camera is at work. The warp is rather suttle but obviously not good.
08-22-2010, 11:35 AM
Mill run steel is not always perfectly flat unless it is precision ground so the warp may have been there to begin with.
08-22-2010, 11:53 AM
Um that stinks...is there anything I can do other than buy precision ground the next time?
08-22-2010, 01:24 PM
If you are going to make blades you are going to have to learn to straighten them. Warping is a common problem. I forge rather than do stock removal, or more accurately, I forge and grind rather than just grind but I usually have to straighten my blades after initial grind. At some point(s) in heat treating I use a bending fork to straighten the hot blade. My bending fork is a hardy tool but you can use two metal rods held in a vice to do the same thing. Yesterday I tried a new technique, for me, and used three rods in a vice to cold straighten two blades. To do that you put one rod behind the curve and two to each side of the curve in front inside the jaws of a vice. Then the vice is tightened to cause a counter bend and, hopefully, straighten out the blade. I admit that it was rather nerve racking tightening down the vice and expecting to hear the dreaded "ting" at any time.
08-22-2010, 08:36 PM
I'll do some more investigating and try to straighten the blade. BTW I am currently enrolled in a Blacksmithing course and will hopefully be doing what you are.
08-22-2010, 10:05 PM
It was likely that way when you received the steel. Even precision ground won't always be straight, as the precision grind is just for the surfaces to get them parallel to a uniform thickness. During shipping, a 3' length or more of steel can and likely will take a slight bend.
You can easily straighten things out. I recommend straightening while hot. What I've done is to stress releive at 1200F or so and then straighten while hot with a wooden mallet or a bending fork. If you don't have access to a controlled heat source, you can heat things up to just at or below your first sings of color. Just be sure to do a normalizing cycle prior to heat treating.
08-23-2010, 10:52 AM
This is a rather slight bend, when placed on an anvil i can see light between the two. would a torch and a vise work?
08-23-2010, 12:17 PM
Yep. Remember, if you get it too hot in one spot, that spot is going to bend first, and you'll end up with a different funny bend in the steel. Spread the heat evenly over the radius of the curve, and gently bend it just past neutral, let go, and see if it corrected things. You'll likely have to go just a bit farther than you think to get it to correct. After correcting the curve, be sure to normalize to account for the extra stress you introduced into the steel, or else you may end up with a warp during your heat treating.
08-24-2010, 12:16 AM
08-24-2010, 10:25 PM
And, don't wear gloves while grinding.
Seems like a good idea, and I've done it, but you can catch that glove materials in the grinder and do some serious hurt to yourself.
08-26-2010, 11:23 AM
Another reason not to wear gloves, at least during secondary grinding after heat treating, is that they can keep you from noticing that you are over heating your blade from the friction and changing the temper of the blade.
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