2Tim215

My quest for a "coaless" coal forge

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For those that might be interested. After a few failed attempts to get what I wanted - a "coaless" coal forge that would heat up any size or shape at specific areas and could be changed to suit the shape and size of an object - I finally succeeded.

Using only one burner and 1lt/hr of waste veg oil:

After 10 minutes

1-1.jpg

After half an hour

2.jpg

3.jpg

4.jpg

This is now my primary forge for blacksmith work and knives. One instead of the three I had previously.

The heat rises from the 100mm radius hole where the burner is like a fire pot and heats the steel placed above. The roof is adjustable and cast and I can place the fire bricks to suit my needs.

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That's a really neat way to do it. Good way to recycle vegitable oil! I guess when you run out you'll have fried chicken more often!!

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What a wonderful project and show of creativity! Would you be so kind as to post a picture of the final burner plumbing?

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Thanks all - here is a pic of the burner setup - don't get it then feel free to ask - this is temp while I wait for my burner nozzles to arrive from the states - three months I have been waiting now!!!

Oilburner.jpg

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That looks like a great set-up. I was looking at the calculations on your website, and it really does seem to be an affordable choice for a forge. What sort of PSI are you running your air at? My main concern for a forge like this (for my shop anyway) is that I wouldn't want an air compressor running all the time.

I really like the looks of it though. I will have to look into vegetable oil as an option for my forge design now.

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So, your oil spray is formed by blowing over the hole in the oil feed pipe. Very easy, and ingenious!

Is your oil feed to the hole pressurized, or under gravity feed, or only fed by the air blowing over the hole?

Phil

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Hi Ben - I have a 3.5 HP 150 ltr compressor and with this home made burner my compressor kicks in every 30-45 minutes for about 3 minutes to bring up from 6.5 bar back up to it's 8 bar limit. I could set it to run down to 5 bar but then I run the pump longer to get to 8 bar again. I would rather have frequent short intervals than infrequent longer intervals. My regulator at the burner runs at 2 bar to 2.5 bar pressure, but remember that the air outlet is only a 0.8mm hole so this only effects the air speed for atomization and does not reflect the actual amount of air blowing through. So in answer - you won't be running your compressor so much that you over run it's duty cycle. Also I am not using the siphon nozzles that I have ordered - with these you only need 5 - 10 psi of air pressure to atomize and PULL the oil through.

Links to nozzle:

http://www.patriot-s...38;startRow=341

And it's use:

http://www.metalcast...l-siphon-nozzle



The you tube vid is what I based my idea on, but when my nozzles arrive is what I will actually use. He has two vids - 1 of burner in action and 1 of the burner build.

Hi Phil - my oil at this time is gravity fed, again when my nozzles actual arrive this will change slightly

One thing I failed to show and mention is that I do not need the cast roof or walls - I have and can run it open as I would any coal forge and it heats up whatever is above the hole, except anything (plate) that covers the whole area of the hole - for this I just place some fire bricks and rest the plate on them above the hole.

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Here's a update with open forge

80X16 flat bar - cold to red in 7 min

A-1.jpg

25X5 flat bar - cold to red in 4 min

B-1.jpg

The lighting doesn't quite reflect the high red color.

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Tidy job, Tim.

I've not tried playing with oil burners, but it looks like fun. How easy are you finding it to vary temperature with the Babbington? And have you been able to get welding temperature out of it yet?

I'd expect it to be easier to vary the mixture/temperature with the syphon system, once it arrives. My understanding of oil burners isn't great, but the Babbington seems to have a lot of things that aren't easy to adjust independently, yet need to be very close to optimum, in order to work even moderately well: a bit like a Venturi setup vs a blown burner on gas.

As Ben says, it might not be ideal running a compressor all the time, but there'd be nothing really stopping you running Propane instead of air to atomize the oil. Most of the Babbington burners I know of, use tiny nozzles at around 0.25-0.3mm (.010-.012") for atomization. Because the gas- or air-flow varies with nozzle area, at any given pressure, they'd use around 10-15% of the gas that a 0.8mm (.032") MIG-tip burner would use, with the rest of the heat provided by the oil. It's still a worthwhile saving.

Please let us know how you get on when the syphon setup arrives.

Regards

Tim

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Bottom burner forges tend to have problems with stuff, (scale, slag, refractory bits, etc) dropping down the hole and building up causing burner issues. Does your design have provision for this?

It looks great but what about putting the Burner in the movable top piece; I know it doesn't localize the heat as well, but it does allow things like use of flux without problems.

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Updated with new burners


Some vids with the small forge running with the new Hago nozzle.


With choke open.



With choke closed.



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Some more

After 5 min from start up.



After 15 min - welding heat.


These nozzles are not cheap but work like a dream once you figure out what burner size works best.

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really nice idea and well executed.

it's basically a ramjet - brilliant application of the principle.

Wouldn't worry about the compressor noise...the jet will probably drown it out..;)

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VERY NICE ! My first gas forge was blown, bottom fired, propane fuel . It worked well I still have the castable body in a corner some where. If I were to build one I would start with that forge body.

For years I have been thinking that I would like to build an oil fired forge. I have been reluctant to proceed with that project because of concerns that an oil fired forge inside my shop might not be a good Idea. I my world Murphy Rules. If something can go wrong then it will.

The featured forge is a wonderfully creative and functional forge . But I can't help but wonder if it is Murphy Proof. Having said that - For years I heated my house with oil so there are bound to be ways to make this kind of forge safe. But would the Insurance companies accept an un-tested home grown system if something were to go wrong ?

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Knots, I find the oil forge safer than the gas forge. Oil won't pool like gas and explode and only ignites if atomized or if at boiling point. The chances of oil reaching boiling point in the line or container are nil and the little that has occasionally pooled in the forge burns away. Not much can really go wrong besides a dirty jet or using a nozzle to big for the volume of the forge - then it gets scary hot!

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Tim, thanks for sharing, I too have wanted one like this for a while. I have several questions if you would be so kind.

how are you starting your fire with the new nozzles? I don't see a propane line.
what size/deg spread nozzle did you use?
are you still gravity feed with the new nozzles?
Are you having to preheat the oil like the metal casting video?

Thanks again!

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Tim, thanks for sharing, I too have wanted one like this for a while. I have several questions if you would be so kind.
No Probs.
how are you starting your fire with the new nozzles? I don't see a propane line. Most times I use a torch and light the burner outside - usually lights immediately.
what size/deg spread nozzle did you use? Using a 609.4 Hago nozzle (.4 gal/hour) in the forge in the vids and I get welding temp quick, also have a .85 but that one is scary dangerous in a small forge.
are you still gravity feed with the new nozzles? I have the oil container about 500-1000mm and this works well
Are you having to preheat the oil like the metal casting video? Most times no, depending on viscosity, outside temp and if I dilute 10 diesel or not.

Thanks again!


Hope that helps. Oil must be very clean though or nozzles block so I filter twice before using, Have also found that the groove on the nozzle for the O ring is not cut right so have to replace every now and then if O ring gets damaged. There can be no air leaks on the system or it won't siphon the oil.

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There can be no air leaks on the system or it won't siphon the oil.

Thanks, this is sounding more like what i need.
I am a little confused on the above quote. The air is still blowing past the nozzle at a 90 deg angle, or did that change?

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A hago nozzle is a siphon nozzle and has a O ring - if there is a leak at the O ring it won't siphon. If there is a leak anywhere on the oil line where it can SUCK air it wont siphon properly. A leak at the O ring causes it to blow air back up the oil line. A leak on the oil line affects the siphon ability.

Hope this helps.

We have had to take all the nozzles we bought and re lathe them to fit the supplied O ring as they were all 0.5mm out and that is why they were all tearing.

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What about using a preasurized fuel tank ? 1 or 2 PSI would probably be plenty of pressure to move the fuel. This would be an advantage for portable forges. It would be easy enough to dedicate a regulator since the featured burner already uses compressed air.

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The moving of the fuel to the jet isn't really much of a problem. The important thing is getting it atomized finely enough to give a consistent burn and this can be done with oil pressure (lots of it) or with air moving at high speed.

One of the advantages of a syphon system is that the air that provides the atomization, also provides the motive force to get the oil to the nozzle. If the air stops, so does the oil.

A pressurized oil feed with air atomization means that extra controls are necessary to cut the oil feed when the air stops, so the complexity increases.

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The moving of the fuel to the jet isn't really much of a problem. The important thing is getting it atomized finely enough to give a consistent burn and this can be done with oil pressure (lots of it) or with air moving at high speed.

One of the advantages of a syphon system is that the air that provides the atomization, also provides the motive force to get the oil to the nozzle. If the air stops, so does the oil.

A pressurized oil feed with air atomization means that extra controls are necessary to cut the oil feed when the air stops, so the complexity increases.



OK, so the using the syphon system goes straight to the heart of the safety issue, Thank you for that.

The featured forge uses vegie oil. How does fuel oil compare with vegie oil in terms of heat content, ignition temperature and general characteristics otherwise related to safety ?

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