Neat little oil forge blower

[JohnK 32]

OK so I've been experimenting with quite a few different oil forge design's and I believe I've found about the best so far. First what I notice on many sites and YouTube  videos is generally the same sketchy thing over and over, none are shown actually powering a forge. From experience I can say most won't work in a forge, mainly due to back pressure. Secondly most are quite large and have multiple flame holders. That's a hazard all in itself. So I thought why not give it that much needed flame holder but put it to work instead! Also see just how small I can make this thing. Presently I'm using a small propane bottle 3"x10". This was another test to see if the design would work. Indeed it does!  however if anyone intends to build it I'd strongly recommend a thicker steel tube (say 1/4"+) and around 3"-4" in diameter. And possibly thick threaded collars welded to the burn chamber for intake and 2 exhaust tubes as they will eventually degrade and need replacing. If there's any questions or suggestions I'll happily answer. Currently I'm testing efficiency. And while I'm not sure if it'll weld I know it easily maintains forging temps. I probably need a better air supply. 

[JohnK 32]

[JohnK 32]

32oz lasted for 40 minutes. That equates to a gallon running for 2.6 hours at forging temperature. Fuel mix: 2parts waste engine oil, 1part diesel, 1part gasoline. 

[Martin Tiney 61]

Do you get any carbon build up from the flame? 

We used to have a waste oil heater in one workshop I worked in we had to de coke it at least once a week! 

[JohnK 32]

Indeed it does(well provide carbon) @Martin Tiney. Luckily no carbon buildup. Generally a little soot layer when running a caburizing flame. It can run neutral or reducing but I always let it run a little over so I don't get carbon loss. The tank and exhaust runs to hot to allow buildup and the interior of the forge has nowhere for it to cling(it's clay). The only downside I've seen is that the oil does need mixing with gas because of the small size and how thin the metal is. A thicker chamber should omit the need once hot.

Edited November 18, 2019 by JohnK

[JohnK 32]

Refractory mix: a guesstimate. 10 parts drywall compound. 2 parts white latex paint. 5 parts plain sandless clay.??. I'm not sure just a guess. Seems to work well and I only used it as a sealant for my forge. But it seems to hold quite well. I used what I had. I'll keep updating as I improve. 

[JohnK 32]

Turns out nearly anything roughly that size will do. However this being quite thin the efficiency has been reduced. 

[JohnK 32]

Update. Seems 3x10 is good. Thicker metal is still advised. Brings steel to bright yellow. Chamber itself remains dull red to black. 

[JohnK 32]

[Martin Tiney 61]

Have you fitted a restriction to atomise the fuel going through, or is the only form of regulation the tap on the fuel supply? 

 I do like the simplicity of this build and I shall give it a try as I have an almost endless supply of waste oil and waste fuel from my place of work.

   

[JohnK 32]

It's a plain ole drip feed with the fuel outlet near the end of the intake tube/tank joint. It doesn't atomize the fuel but it does turbulate? It. Is very simple and reliable method. Intended to be simple so anyone can build it. I'll try to make a better schematic later. The fuel in is about an inch from the tank end of the air intake tube. I doubt it's important. Keep in mind the chamber must be hot before the addition of just oil. I use gasoline but propane should work just fine. 

[Martin Tiney 61]

Thanks, I look forward to seeing the schematics 

[JohnK 32]

I may have missed something. I apologize about spelling.

[JohnK 32]

Addendum. If 6"ID or greater chamber is used id suggest shorter length, say 8" or less(6"x6" is great). this of course may not work as a double burner design but will make an excellent single burner for a smelter or small knife/general use forge though a 1/2" pipe as a flame holder, opposite of exhaust, is needed. Also the fuel flow should be finely controlled. 1/20th of a turn on mine is the difference between oxidizing, neutral, and carborizing atmospheres and im using the valves from an oxy/acet torch head. Inline fuel filters a must. I dont care how much you "think" youve filtered it.

Edited November 28, 2019 by JohnK

[JohnK 32]

2 1/2" chamber with 1 1/4" intake/exhaust. Turns out just about any size will work. The smaller chamber is much more aggressive with flare up but generates the same heat and is a little more fuel efficient. 

[JohnK 32]

Test design. Ease of ignition and will not extinguish itself. Very fuel efficient. Heat lacking. 

[JohnK 32]

Discovered an interesting clay mix for forge body by half accident today. Seems adding around 1% powered softwood charcoal gives it an interesting insulation boost. Quite high might i add. Ive had it running for approximately 3 hours now and the outside is still wet and lukewarm at best. The inside is yellow. Im taking a shot in the dark and assume the charcoal burned out leaving a porous clay shell. Originally added charcoal powder as a way to assist in drying without cracking when fireing instead of waiting days for the clay to do so on its own. Overall thickness is 3 1/2in all the way around 

 

Edited July 26, 2020 by JohnK
More information

[Oberu 106]

That is very interesting.  I'm wondering if this could be adapted into alternative fuel forges.  I'd assume so.  How does waste oil rank on cleanliness?  I refer to forge welding.  One of these days when I have land I'll build a proper forge but for now my little propane rig will work while I'm in a single car garage.

[JohnK 32]

My oil forge will actually burn any fuel once up to heat. vegetable oil, waste engine oil. probably gear oil if thinned. easily anything else. i start mine on gasoline or kerosene depending on my mood and switch to waste engine veg oil once hot. cleanliness is a bit of a personal matter. it seems to always want to burn neutral or slightly decarb with no smoke or smell. however i recommend a small amount of black smoke, very small, to provide a safe forging atmosphere. overall im happy with it and its fairly easy to deal with.

[JohnK 32]

tomorrow ill post pictures of the dimensions of everything and a clearer view of the atmosphere inside the forge.

[JohnK 32]

Fire drying a smelter. Considering ditching oil for charcoal to forge but definitely keeping for smelting. Hippocratic? Yes. But smelting is by far more important to me as forging is a hobby. Smelting billets would help me accomplish other things.

[JohnK 32]

Consider my self lucky. Looking inside burns my eyes. Its hot. Hot hot. A glance revealed white inside. 

[Charles dP 585]

There’s a thread somewhere in shop safety (I think) about eye protection for IR when looking into gas forges.

[JohnK 32]

Worry not. Wont do it again. I was just taking a quick looksee. Normally when its flared up like in the pic its at its coolest. It was only a "do i need to adjust something?" Peek 

[JohnK 32]

It can also be changed to work vertically with double exhaust. This setup was proof of concept. Was run less than 30 minutes using strictly gasoline and kerosene. Not yet oil tested.