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Issue with marks in the blade


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Greetings,

after a long time lurking on this forum, I finally decide to post, unfortunately because I have a problem.

I am trying to reproduce a dagger from a movie as a Christmas gift, and as I was grinding it, I discovered many, many marks on the blade. I managed to grind a lot of them while maintaining a homogeneous thickness, but there are parts where I just cannot get rid of them. I used a brush before and after working the hot blade, and always wiped the anvil to remove the scales, yet it is still badly damaged.

Is there any solutions to fix this issue ? Should I put it back in the forge to try to correct it, or is it irredeemable ?

I am a beginner ; I've built my first forge a year ago with bits and pieces, but barely had the time to work. Thanks to unemployment, I work at the forge nearly everyday since early September, but I am still learning on my own, though with all the resources on this forum and elsewhere. By the way, this is a good opportunity to thank you all deeply for all the knowledge here !

Thank you very much in advance for your insight !

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I looks like those are places where the steel was overheated (possibly in an oxidizing fire) and produced excess scale.  The way I see it you have 3 options: leave them there, continue to grind them out, or reheat the blade to a planishing heat and smooth them out with a hammer/flatter. I would probably pick the last option if it were me.

By the way, cool blade, what movie is it from? It looks sort of elvish to me.

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Thank you for your answer. I indeed discovered only recently that I might have been inserting the steel too deep into the forge, though I never saw this blade melt. Perhaps it caused some damage nonetheless. I think I'll heat it back and try to do as you said.

You saw correctly, it's Aragorn's dagger from Lord of the Ring :) My brother and I deeply appreciate these movies / books and I wanted to craft him a dagger from the movie. This one seemed amongst the least difficult to recreate. It's been quite challenging so far, but now I feel much more confortable forging a classic knife.

 

If by happenstance some might be interested in seeing the result of the planishing - or even the final result - I can update this post later.

 

Thank you again !

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Even if it didn't burn, all the excess oxygen will make a lot of scale and cause that sort of pitting. It will also degrade the steel so it should be avoided whenever possible.

Ah okay, nice. Great movies/books.

Certainly, feel free to share some pictures along the way. We like pictures.

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So it seems like you're left with option 1 or 2 (or some combination of the two). Even if it isn't as flat as you originally planned I wouldn't call it a total loss. I've never tried to make a knife that long, but I doubt they all turn out how you originally planned. Especially when you're just starting out.

What kind of steel is it made of? What's your plan for hardening and tempering?

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This is why the adage of "Forge thick, and grind thin" was adopted.

When looking for a flat surface I use light hammering and work the whole surface over to get it as even as I can.  You really need to watch the impact spots when hammering and adjust as you go to avoid dents and waves. It takes a lot of practice, but keep at it.

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I had planished it at 4mm of thickness, so that I could grind it without too much worrying. The issue is that I tried to forge the bevel (don't know if that's the proper word) instead of fully grinding the edge, and I shouldn't have done this, since the edge have pits aswell. My other problem is that I use a very old and worn-out belt grinder, and the belt is discontinued on the market. It makes the grinding process very long since the belt is exhausted, combined with a lack of power.

 

I do not know what kind of steel it is. I know how dumb it sounds, but I started by gathering remains from the house and from friends. I've been throwing away a lot of steel as I discovered how bad some of it was (some cracked in many thin layers as I heated and worked it ; other simply never hardened after quenching, ...). I am a bit worried actually, because I'm running out of good steel and I simply cannot find a way to purchase some. I visited and contacted many companies dealing in steel around where I lived, whether it was second-hand material or industrial distributor, and no one sells steel capable of sustaining thermal treatment ... Some professionals even have never heard of the type of steel I've been looking for (french / european standard : XC75. And the industry apparently only deals with S235).

 

And to finish answering you, Frazer, I'm not sure what you imply by "plan for hardening". I use vegetable oil (sunflower) for the quenching, and temper it once in the oven. Since I lack a lot of knowledge in metallurgy (in fact I am lacking in many other aspects), I adopt an empirical approach : 220°C for 2 hours in the oven, and observe the results. If I feel it didn't work, I change the parameters for the same steel on future projects.

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You might consider going to an automotive spring shop and asking them for some cut offs.  Both coil and leaf spring can be made into quality knives, longer blades like you are making in particular.  If your grinder doesn't cut you can always go the hand finishing route.  Anneal your finished forging in a barrel of wood ash.  When cold soak overnight in white vinegar to dissolve scale.  Draw file bevels with first a coarse 12" bastard file then a finer tooth one.  Hand sand to 120 grit with sanding block.  Heat treat using the proper normalization, quench and tempering process for your steel (probably 5160 or 9160 will work).  Final sand to at least 300 grit with sanding block and put on a handle.

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I know that there are several places in the USA that will make custom length belts for grinders that are no longer supported.  You may want to ask around for a similar business in the EU.

I second the suggestion about buying "drops" from a spring place.  You can pass the ABS Journeyman's test with a 5160 (spring) blade!

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