Here goes nothing (photo heavy)

[Joshua States]

So a few months ago I built this crucible forge kinda thing. I lit the wood fire in it and let it dry out for a bit. Then I tried running it to see how hot it would get. Then it sat dormant  waiting for me to find time and acquire all the necessary materials for a run.

 

 

This weekend, I went for it, but the results were less than desireable.

Here is the setup.

 

 

The air/gas mixing assembly.

 

 

I need to change that ball valve out to a gate valve and there aren't any available in the size I need locally. I have to order it.

I had a lot of problems with burner blowout and failed to get into the right temperature without excessive fiddling with the air/gas mixture. I only got the furnace above 1500 C for about 6 minutes before running out of gas. I have no idea what's lying below the slag layer.

 

 

 

 

 

 

[Gazz]

Is this for melting non ferrous stuff?  What is the issue with the ball valve vs a gate valve?  Something like this has been on my projects to do before I die list.  Does the furnace exhaust through the top around the crucible?  More details please. 

[Alan Longmire]

I'd lose the needle valve.  If you're registering any back pressure at the gauge you're not dumping enough gas into the system.  If you must use the needle valve, use a 1/8" orifice for the gas injection.   Or even a 1/4" ID bit of pipe.  Use the regulator to control gas flow otherwise. The ball valve on the gas line is just for emergency shutoff, right?

 

Is your blower one that can run on a router speed control/variac?  Those are far easier to control airflow with than any valve.  

[Joshua States]

12 hours ago, Gazz said:

Is this for melting non ferrous stuff?  What is the issue with the ball valve vs a gate valve?  Something like this has been on my projects to do before I die list.  Does the furnace exhaust through the top around the crucible?  More details please. 

It can be used for either ferrous and non-ferrous materials. Yes the hole in the top is where everything exhausts. The ball valve is very difficult to get small changes in airflow. Small changes in airflow yield large changes in temperature. Both upward and downward. I have a gate valve on my ribbon burner forge and it works great for small changes in airflow.

 

10 hours ago, Alan Longmire said:

I'd lose the needle valve.  If you're registering any back pressure at the gauge you're not dumping enough gas into the system.  If you must use the needle valve, use a 1/8" orifice for the gas injection.   Or even a 1/4" ID bit of pipe.  Use the regulator to control gas flow otherwise. The ball valve on the gas line is just for emergency shutoff, right?

 

Is your blower one that can run on a router speed control/variac?  Those are far easier to control airflow with than any valve.  

It's not a needle valve. It's one of those 4-detent ball valves. When you fire this thing up cold, it doesn't need much fuel to get up to 800 or 1K degrees C. As it warms past that point, the fuel consumption to get above that increases dramatically.

The 4-detent function allows for starting at half-open, increasing in smaller increments as the heat rises. I have the same valve in my gas line on my ribbon burner forge. Crack that open a half-click and you go from forging heat (1900-2000 F) right up to welding heat (2150-2250 F) in about a minute. Adjust the air flow with the gate valve about 1/4 turn and you have a pretty nice almost neutral flame.

The orifice is an 1/8" hole in the brass pipe. I start at 8 psi on the gas line and as soon as I open the red valve (yes, it's a shut off switch) the pressure on the line reads basically zero maybe 1 or 2 psi. When I open it all the way, it's zero. The blower isn't rated for variable speed, but I have used a simple light dimmer to try that method. It's also too difficult to get small adjustments. It's a small slide and I have fat fingers

 

Edited February 14 by Joshua States

[Alan Longmire]

Ah, gotcha.  I didn't know those 4-way detent valves existed, thanks!  

[Jan Ysselstein]

Joshua,

               You might try placing a “T” in the line and placing the  valve on a short side line , using that valve to vent off unwanted volume from the blower. If the valve is closed all your air stays in the system …if the valve is wide open you are running low flow/pressure. Maybe add a second T closer to the furnace where a 1/4” needle valve controls the gas flow into the moving air. The flame is controlled by the regulator…probably set at 5 psi and the air vent valve and the needle valve.and perhaps the intake to the blower.1” pipe just about fits into 1 1/4” pipe I use that combination a lot to quickly connect or disconnect. I will send a picture of what I have (although I am using a brush type vac blower and a variable transformer….. .

Edited February 16 by Jan Ysselstein

[Joshua States]

@Jan Ysselstein I think I get what you are saying, but I'd love to see your setup. Mine is still a little finicky.

 

I did manage to get two melts done over the weekend. The first one had to be fired twice, was an absolute bear to get out of the crucible, and looks a little weird.

 

 

It wasn't sparking very well at first and I was not confident that it was a good melt. 916 g out of the crucible.

Dan Cauble suggested I grind a small area on the side to see the interior and that proved to be a good idea.

 

 

I can see some porosity, but it was sparking much better the deeper I went.

The second melt provided a very nice puck that fell out of the crucible after removing the glass slag.

 

 

This one sparks very nicely and looks much more  solid. 992 g weight out of the crucible.

 

[Alan Longmire]

Sweet!  Now you get the fun of forging it...  

[Joshua States]

1 hour ago, Alan Longmire said:

Sweet!  Now you get the fun of forging it...  

Later. I'm going to bring these to the show in OKC this weekend. Just to have on the table as bait.

 

I also did a third melt today. This one was rather exciting. I used nothing but black sand and charcoal for the charge. The furnace got so hot it started to boil violently. No photos, but a video is coming to a YT channel near you.

 

[Jerrod Miller]

28 minutes ago, Joshua States said:

I also did a third melt today. This one was rather exciting. I used nothing but black sand and charcoal for the charge. The furnace got so hot it started to boil violently.

Sounds like a carbon boil, which isn't actually boiling (as in hitting the boiling point of iron), but is so called because it looks like a pot boiling.  This is the oxygen in the system (in this case from the ore, but sometimes it is intentionally injected as a gas) combining with the available carbon to form CO.  This is done intentionally in industry for a few reasons.  It is an exothermic reaction (literally burning C), so it is a way to get heat.  It lowers the carbon content, so getting an over-spec C is easily brought down.  The extra gas in the melt can help drive out other gases (like N and H), then the excess oxygen is easily dealt with via Si/Al (or other) additions.  

[Joshua States]

Whatever it was, it made a freaking mess!

I sanded the windows to 220 and tried a light etch to see any dendritic patterning.

First puck, not much to see.

 

 

Second puck looks better

 

 

 

[Hoy's Forge]

I've considered  attempting this  everytime I clean up my grave yard and think if I could just chunk all of these into a cruicble  with some glass maybe they could be recycled !  I have a bit of hoarder in my blood.  Are you using black sand exclusivly  ? Or do you have other materials in mind? 

[Gerhard Gerber]

I have to make space for a new grinder and bandsaw, hopefully/maybe reorganize, clean up and generally make my shop easier to clean.

One of the problematic items is several bags of very high quality local iron ore.

I dream about putting a knife literally made from this country on my table (at a ridiculous price), I've asked advice here, dutifully put all that information together in a document.

Still missing a suitable place to do this, and one or two crazies to help, and in the mean time those bags of dirt are seriously in my way.

 

Then I see threads like this, and those bags become my precious    

[Joshua States]

16 hours ago, Hoy's Forge said:

Are you using black sand exclusivly  ? Or do you have other materials in mind? 

The two pucks above were made from pure iron fed stock and charcoal, with a little something for carbide donor. The black sand try was on a whim. Pringle says he does that all the time, so I figured I'd try it. What Pringle didn't say was "Watch out for the carbon boil, it will really freak you out".

 

You can certainly re-melt all those scraps and broken dreams knives into useable stock. An A4 crucible handles a 1 kg charge easily. It might get a little more carbon from crucible uptake, but that never hurts. You would need to cut them into small pieces to get them in the crucible as tightly packed as possible.

Or you could build a short stack ala Emiliano does and melt it all into a handy bloom and process it from there.

 

5 hours ago, Gerhard Gerber said:

Still missing a suitable place to do this,

I have wanted to make steel ever since the first time I saw a video of @Mark Green pulling a bloom out of a stack. Liz took a dim view of me building Frankenfurnace in the back yard, so that wasn't an option. Then she decided that she wants to melt and cast metals like copper and aluminum........now she needs a crucible furnace.

So I can do crucible steel.

 

[Joshua States]

@Hoy's Forge see this thread by @Aiden CC:

 

[Hoy's Forge]

Thanks Joshua  !  

[Kreg Whitehead]

On 2/21/2023 at 12:44 PM, Joshua States said:

The two pucks above were made from pure iron fed stock and charcoal, with a little something for carbide donor. The black sand try was on a whim. Pringle says he does that all the time, so I figured I'd try it. What Pringle didn't say was "Watch out for the carbon boil, it will really freak you out".

 

You can certainly re-melt all those scraps and broken dreams knives into useable stock. An A4 crucible handles a 1 kg charge easily. It might get a little more carbon from crucible uptake, but that never hurts. You would need to cut them into small pieces to get them in the crucible as tightly packed as possible.

Or you could build a short stack ala Emiliano does and melt it all into a handy bloom and process it from there.

 

I have wanted to make steel ever since the first time I saw a video of @Mark Green pulling a bloom out of a stack. Liz took a dim view of me building Frankenfurnace in the back yard, so that wasn't an option. Then she decided that she wants to melt and cast metals like copper and aluminum........now she needs a crucible furnace.

So I can do crucible steel.

 

I am really diggin this thread. To be clear you didnt make hearth steel first in like a 7 brick fire deal and charcoal....you just put the iron and charcoal in the crucible?

As far as black sand....I assume we are talking regular old maganatite?? 

I was kinda planning on making the hearth steel first.....then into the crucible to consoladate it.

 

[Joshua States]

On 2/24/2023 at 3:47 PM, Kreg Whitehead said:

you just put the iron and charcoal in the crucible?

Yes that is correct. Iron grain, either small pieces or these handy 1mm spheres I got.

 

On 2/24/2023 at 3:47 PM, Kreg Whitehead said:

assume we are talking regular old maganatite?? 

I have about 30 pounds of magnetic black sand. I believe this is magnetite.

 

On 2/24/2023 at 3:47 PM, Kreg Whitehead said:

was kinda planning on making the hearth steel first.....then into the crucible to consoladate it.

The short stack furnace that Aiden is using refines iron into steel bloom. Bloom needs further refinement through forging, folding/stacking and welding to become a homogeneous (or mostly homogeneous) material.

 

The crucible method takes raw iron or iron ore, and combines it with a carbon source to create a homogeneous steel ingot. 

[Kreg Whitehead]

I dont know anything....obviously. And am still struggling with the terminology. I was in hopes of melting the bloom material in a crucible.

In my head it seems like it should work. If someone can explain why it wont that would be kewl. I am not forging anything more than a simple san maii by hand on my rr track.

I do have a little tax return money and was thinking of buying a ba shreeder kit. Maybe I should focus more on some kind of a home grown press.

[Alan Longmire]

You can certainly run bloom through a crucible melt.  It just needs to be high carbon to start with OR have a lot of charcoal in there with it.  That's how the English figured out crucible steel for clock springs in the 1760s, took a lot of high carbon shear steel (carbuzized wrought iron, refined by folding), put it in a crucible with lid to prevent oxidation and subsequent decarb, and cooked it until liquid.  The slag floats to the top and leaves clean steel.

[Joshua States]

5 hours ago, Kreg Whitehead said:

I was in hopes of melting the bloom material in a crucible.

In my head it seems like it should work.

And it will work, providing the bloom is iron, or low-carbon steel and you add the charcoal to increase the carbon level. If you end up with cast iron bloom, it will not work, you will just get more cast iron. You can tell if it is cast iron, by heating it up and trying to forge it. If it forges OK, it is either iron or low-C steel. If it falls apart or melts on you, it is cast iron. Really high-C cast melts really fast. See this thread: 

 

[Joshua States]

OK hive mind. I have an enigma, at least to me. Probably not so mysterious to those of you with more metalurgical saavy and knowledge than this old man. When I stopped the boiling sand melt, I eventually chipped the "stuff" out of the crucible. I wound up with a buch of rock-like nuggets.

 

 

These are somewhat sparkly on the top side, and dull on the bottoms.

 

 

They are definitely magnetic.

 

So here's the big question: Should I just put these in another crucible melt, or should I use these as feed stock in a short-stack melt?

 

Edited February 27 by Joshua States

[Alan Longmire]

That's what me and Larry Harley got the last few times we tried direct ore reduction in a crucible.  He died before we did anything else with it.

If you cook it again you may get a small puck, or maybe just slag.  I'd save it for a short-stack run, and add a little rust.  Magnetite gets sticky slag that tends to clog the furnace.  Lime makes it worse. 

[Aiden CC]

16 hours ago, Alan Longmire said:

That's what me and Larry Harley got the last few times we tried direct ore reduction in a crucible.  He died before we did anything else with it.

If you cook it again you may get a small puck, or maybe just slag.  I'd save it for a short-stack run, and add a little rust.  Magnetite gets sticky slag that tends to clog the furnace.  Lime makes it worse. 

Is this stuff something like a mixture of ore that got reduced and some which was just melted? I can imagine that if there wasn't a clear slag layer, this material may be a challenge as would be a good deal of non-metallic material that needs to be separated. I have a ~10 lb pile of rusty shavings and swarf I've been thinking about running through a hearth, but haven't yet since I'm not sure how much reduction can happen in such a short drop.

 

Nice work @Joshua States, crucible steel is something I've wanted to try, but my small melting furnace for non-ferrous work just doesn't have the heat output to do steel. It's cool that you can see the dendrites so clearly, you could probably get some interesting insights from the primary and secondary arm spacing (distance between the "trees" and distance between the "branches"), as they are a product of composition and cooling rate. It would be interesting to see what the cross section looks like further away vs. up against the edges of the puck. I'm not sure if wootz intends to use columnar (same orientaion, from) or equiaxed (random orientation) dendritic growth, or some mix, but I would imagine that also has subtle influence on the pattern. If I had to guess, I would say many of the dendrites in the etched photo grew "into the page", and what we see is like looking up at a tree from underneath it. Cool stuff, I'm excited to see where this goes!

[Alan Longmire]

3 hours ago, Aiden CC said:

Is this stuff something like a mixture of ore that got reduced and some which was just melted?

 

No, it's a foamy mass of slag with steel prills interspersed.  I think a shaft furnace is the way to fix it, maybe with added silica.