Forging imperfections

J

jawilder

Joined
Jun 27, 2006
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I have forged 6 knives or so and in every one of them there are small holes where I hammered. They don't go all the way through and can be ground out if I remove enough metal. What causes this and how can I avoid it?

By the way, I'm using a charcoal forge.

Thanks.
 
Are the holes little round pits or do they look like cracks? If you grind off the layer of fire scale down to bright steel, are the holes still there?
 
Kind of hard to say for sure without seeing them. If you are seeing sparks coming off the steel while it is in the forge you are over-heating it. If you repeatedly heat part of the blade without forging on it you might end up with some pits also.
 
It's decarb. some folks like me like it left on the spine as it adds charector to some knives. when you forge have the desired thickness of the knife in mind, & make sure you choose steel thick enough to be able to grind away those pits after forging, if you want a clean look

Jason
 
Hard to say but if each hole is identical, it was probably something stuck to your hammer. Could also be that you hammered scale into the steel if your forge atmosphere is oxidizing.
 
Make sure that you wipe the scale off the anvil between courses.

I'm betting that you hammered a nice fat chunk of scale into the blade and didn't realize it... I use to do it alot in the beginning.
 
You may want to try the wet hammer and anvil technique. With the hammer and anvil wet the scale pops off with a loud bang. I have never made it work properly for me but a lot of people claim it reduces scale a lot.
Just what I do, Lynn
 
Get a wire brush to remove all the scale before you hammer. Also try easing up on the air, you may be the fire to air rich which will not help with the scale. Its either that or your using the hammer at an angle.

Jamie
 
I honestly could be making any of those mistakes:

Bad hammering, too hot, hammering in scale. I'll notice to see which ones. Thanks for the suggestions.
 
If the "holes" are crescent-shaped or even just oblong, then the culprit almost certainly hammer control. I have a heck of a time striking with the face perfectly flat to the work. On the flat, not so hard. On the bevels, really takes some practice.
 
Try this, after you have forged to shape, go back on your last few heats and coat the top of your anvil with water, slight coating will do, it will pop that de carb off, I forge with water on top of my anvil all the time to reduce the de carb, works great
 
The scale is certainly a possible part of the problem... but it just sounds like basic hammer control and experience to me.

Hot steel in ambient shop light is a little better at hiding stray hammer-marks than cold steel is.

Make sure your hammers don't have any super sharp corners on them that are biting into your bevels.

Unless that's something you're trying to accomplish on purpose (there's always a need for something outside the "norm" ;) ).
 
It sounds to me like hammering scale into the steel. How hot are you forgeing? also there was some 5160 out there some years ago that had some imperfections in it that was doing exactly what you are talking about.
 
It happens with 5160, RR spikes, and files, so I think it's me. I'm pretty sure it is scale. But I am using a charcoal forge that gets pretty hot, so it could be that too.
 
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