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Propane forge melting copper

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Alright first off thank you for all the imput because im completely new to this craft. That being said i have read multiple threads to diagnose my issue with physical application to no avail. 

Here goes. I bought a single chamber fire propane foundry to melt copper and cannot achieve melting point. The foundry i purchased was beginner on amazon xxxxxxxxxxxxxxxxxxxxx

Cast Masters Propane Furnace w 5KG Crucible and Tongs Kiln Smelting Gold Silver Copper Scrap Metal Recycle  

Now i have swapped out the regulator to adjust the psi to dial it to.. at or above 10psi using a 20lbs propane tank. So far no issues with freezing ( regulator that came with product was not accurate and froze after 10 minutes of run time). 

So i can now run for a decent amount of time at a dialed amount of pressure (10psi)  but cannot achieve liquid copper. I have tried to cover the vent hole partially with the ingot mold to keep heat in. I have tried to dial my air to propane ratio in so that its a decent hot/ yellow burn no go...

The questions i have, is the insultion not adequate to refract heat? Look at amazon specs?

should i cover current insulation in refractory cement to increase temps, (reduce heat loss)

is this mini foundry just not adequate enought??

without going over board how should i modify this foundy to achieve the above problem.  ( im thinking dual flame torches)

Thank youfor your time

Joe Moss


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4 hours ago, timgunn1962 said:

Where was the choke when you tried it?

The choke was at 1/4” open at 10psi propane. I was getting a decent flame and heating but just could not quite reach the melting point. Since i swapped out the regulator that originally came with the kit i believe im achieving a hotter burn then before. Still not sure what the issue is..

8 hours ago, jeremy k said:

Why not contact the maker? - as the listing says 100% customer support - just call.

Tried that... not even close to 100% support

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Welcome aboard Moss, glad to have you. If you'll put your general location in the header you might discover how many of hte gang live within visiting distance.  

14 hours ago, Moss said:

I have tried to dial my air to propane ratio in so that its a decent hot/ yellow burn no go...

If you'll send some pics of the flame in the melter we might be able to help with the problem. Text descriptions tend to be overly long and clumsy. You WILL get suggestions though, even if it's just guesswork from folk who've never tuned a burner used a HOT appliance. The guys who've responded however do know what they're talking about, that's why you're getting such advice. We can NOT make helpful suggestions without enough info. Make sense? 

For instance in the above quoted sentence we can't tell if you're talking about the color of the melter or the flame.

If you're saying your flame is yellow open the choke, it's way too rich! If the liner in your melter is getting that hot, copper should be melting just fine, boil if you don't pay attention.

Take a look through the "Burners 101" section for examples of properly tuned burner flames. 

Ah HAH! glad it took some time to reply, talking to Deb, I haven't read the reviews though I did find it or one like it in a search. Okay, I read some of the reviews and it looks like the main complaints are the poor quality propane hose, that's a B-A-D thing! The other complaint is the sloppy liner, gaps and not fitting is just bad workmanship and is inexcusable. 

Neither is hard to correct. Hopefully your new regulator came with a properly rated propane hose, if not GET ONE! 

Relining it is easy but you'll need to buy some Kaowool. Cut it longer than necessary an inch is probably plenty, don't get silly, to go around the ID and compress it so it fits. This will hold it in place due to the pressure from being smooshed a little. It also needs to be longer than necessary to fit between floor and lid. Let it stick up a LITTLE above the shell and it will act as a gasket. 

RIGIDIZE it! Without rigidizing exposed ceramic wool refractories WILL shed fibers which become harder and sharper once they've gotten HOT. It doesn't need to be fancy, you can buy "fumed" silica at places that sell fiberglassing supplies, it's used to thicken resin so they keep it on the shelf. Mix it with clean water and spritze the blanket, let it dry then fire it. "Forges 101" section covers rigidizing in length.

That's my best GUESS based on what you've told us. Please clarify your issues and post some pics. PLEASE NO VIDEO! Unless you post to Youtube and send up a link. Lots of our forum members are spread around the world and have to pay for their DIAL UP bandwidth. We try to save them the money.  Yes?;)

Frosty The Lucky. 

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The burner looks like a Devil Forge burner. I got one to play with a while back and it seems pretty good and pretty well-tuned.

With the choke fully open, it should make welding temperature, but still be richer than stoichiometric*. As you close the choke, the mixture will get richer and the flame temperature will reduce. It's reasonably progressive and the range of flame temperatures available is pretty useful.

Try again with the choke more open. It should work. If it doesn't get hot enough, open the choke more.

You have 2 adjustments with a choked Naturally Aspirated burner. The gas pressure adjusts the amount of gas going in. The choke adjusts the air:fuel ratio and therefore the temperature of the flame.

As you close the choke, the amount of air available to burn the gas goes down, reducing the flame temperature, and more Carbon Monoxide will be produced.

Carbon Monoxide is deadly, so the only properly safe place to use the system is outdoors. I know 2 smiths personally who have suffered Carbon Monoxide poisoning during 2018. Both were heat-treating and had choked down their burners to get flame temperatures around 1500 degF: lots of Carbon Monoxide. They had previously used their forges inside their shops for forging and/or welding (both processes with more open chokes, higher temperatures and less Carbon Monoxide formation) without problems and did not realize that they were increasing the Carbon Monoxide production dramatically when running choked. One just felt ill, realized the problem and stopped. The other was found unconscious on the floor and taken to hospital. 

Please be safe.

The physics of NA burners means that, once the choke is set, the air:fuel ratio stays pretty constant as the gas pressure is varied. The gas flow varies as the square root of the gas pressure. To double the gas flow, you need to increase the pressure by a factor of 4.

* I have a background in burners, rather than smithing, and tend to think in terms of the stoichiometric ratio.

Whilst the stoichiometric ratio seems like it "should" correspond to a blacksmiths "Neutral" flame, I have a strong feeling that scaling is still a significant problem at stoichiometric and that applying "Oxidizing", "Neutral" and "Reducing" descriptions to air:fuel mixtures based on the effects seen on the workpiece will be more subjective and less precise.  



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16 minutes ago, timgunn1962 said:

To double the gas flow, you need to increase the pressure by a factor of 4.

Isn't that backwards Tim? Double the psi quadruples the volume? I'm asking you as the professional, not disagreeing.

A lot of the scaling IN a forge running neutral or even reducing flame is caused by ambient air drawn in through the forge openings. My shop forge will produce scale internally depending on where I place it in the chamber. If I close the bottom of the openings to the point back pressure starts effecting the burners I can actually reduce rusty steel to clean shiny. CO is a major factor, running that rich so I let the experiment stand as a lesson learned.

Frosty The Lucky.

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23 hours ago, Frosty said:

Isn't that backwards Tim? Double the psi quadruples the volume? I'm asking you as the professional, not disagreeing.

No. I'm pretty sure it's right. 

I certainly hope so, because I've been using orifice plate flowmeters for 30 years on the basis that the flow is proportional to the square root of the pressure differential.

We only run a low pressure differential across the orifice plates at work (and low line pressures). Things can get a little more complex as the pressure differential increases, but it's a good enough rule for most things most smiths will encounter. 

The gas jets we use for burners obviously run much higher pressures than orifice plates, but they are still effectively "just" orifices and the flow being proportional to the square root of the pressure holds quite well up to "about" 30 PSI, when the flow becomes "choked". The use of "long" orifices (e.g. when we use MIG tips) probably introduces a bit of deviation from the square relationship as well, but it's still good enough for government work.




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On 2/23/2019 at 5:35 PM, Irondragon Forge & Clay said:

We still have no idea where in the world you are located. If you were near me I have extra kaowool you could have.

North Ridgeville, Ohio. Sorry about that

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I'm wondering if it's just not turning to cupric oxide---a very copper looking ceramic ond one that forms in the crucible if you do not have the proper atmosphere or proper flux.

I know Terry Griner used to teach casting classes at the Idea Foundry in Columbus and there are a bunch of backyard foundries all around Ohio.

What did they say when you consulted them at the foundry forums at alloyavenue.com?  

Trying to troubleshoot remotely is not nearly as fast or as accurate as getting someone to look at it in person!

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23 minutes ago, ThomasPowers said:

.What did they say when you consulted them at the foundry forums at alloyavenue.com?  

I did not post any questions on that site. I did do some reading of threads to try and diagnose the issue. I posted here because it after looking over the site, it looked more tailored to what I’m doing

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The long yellow flame out the exhaust port is what we'd call Dragon's breath were it a forge. It shouldn't be long yellow and feathery. Flapping like campfire flames. My first thought holds, open the choke till it stops doing that.

Frosty The Lucky.

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10 psi is probably too much, try 5 and open the choke all the way and just play with it till you get a flame that looks like the ones Mike likes in Burners 101. Forget the crucible and leave the top open so you can see what the flame looks like. That's the pic we need, we can't really tell much from the exhaust. Once you get the burner tuned you can turn the heat up and down with the regulator without messing with the choke. 

I'm not a caster but I know molten copper oxidizes easily so a SLIGHTLY reducing flame might be called for. I don't know though, not my field.

Frosty The Lucky.

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