Waste Oil Forges

Discussion in 'Hammer & Tongs' started by David Stifle, Nov 27, 2013.

  1. David Stifle

    David Stifle

    Nov 20, 2008
    I've been doing a lot of research lately on waste oil forges. They are economical, in that the fuel is free, there's no danger of explosions, and they run as hot or hotter than propane. There's a lot of information out there, and a lot of interest, primarily driven by the increasing unavailability and cost of blacksmithing coal, and the cost of propane, and I guess, by a desire to just do it for fun. From everything I've read, they are inexpensive to build and operate (as compared to propane), and reach scary high temps easily. A well designed oil forge can also use propane, diesel, and of course just about any oil (used auto oil, used cooking oil, home heating oil, etc). I may build one this winter, as the idea interests me. Is anyone else interested in this subject, or even better, is anyone using a oil forge?
     
    Last edited: Nov 27, 2013
  2. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    The basic forge build is the same as a propane forge, plus the much more complex oil drip and vaporization system. They CAN explode and catch fire...probably easier than a propane forge. The fuel is cheap, because it is free, but it is not exactly a beginners project. There still needs to be a propane burner to start the forge and get it up to full heat before the oil vapor can burn efficiently.

    Also, the by-products of burning propane are CO2, CO, and water vapor. The by-products of burning waste oil can vary, but some serious bad stuff may be created. I have not researched it much, but things like dioxin come to mind when more complex hydrocarbons get incompletely reacted with oxygen. I'm not saying don't build one, just that there is a bit more than burning oil and getting heat involved. I would research it far beyond you-tube.
     
  3. David Stifle

    David Stifle

    Nov 20, 2008
    You may be right, Stacy. I've done limited reseach so far. There are guys who have these type of forges up and running, and they have not reported any problems related to fires or exposions. As for the design, there's some really simple and workable designs out there, that don't seem to indicate a high degree of complexity. You're right, of course, the chamber needs to be brought up to a dull red before the oil will ignite, and this can be done in several ways, either lighting the propane, or building a wood fire in the chamber. Both work. This is still an on-going research project, I'm learning as I go.

    I haven't read or heard anything about harmful vapor byproducts being a health hazard, but note that the oil forges I've seen were used outdoors.
     
  4. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    The guys who ran these I have talked to used a pre-heater pan/tank or coil to bring the oil up to a warm/hot temperature. Then this was dripped into the hot burner tube where it vaporized while being mixed with the air blast. As with any mixture of volatized flammable particles and oxygen, this can explode if not combusted properly. The worst scenario is if there is a power interruption which shuts off the air blast. If the super-heated vapors of the oil fill the air manifold, and then ignite by the backlash from the chamber, it can be anywhere from startling to serious. The oil drip will not stop running either, so you may be adding fuel to the fire....in this case perhaps a real fire. I know this can happen with a propane system, too, but the much more stable nature of a propane flame in normal air makes that a lesser problem, and a shut-off solenoid on the propane tank makes the issue moot.

    Some folks use a burner out of a home oil heating burner/boiler to handle all the aspiration and air mix. This is a pretty good method to make a waste oil burner. With any such system, clogging the burner is the biggest problem, so filtering of the oil is a necessity. With a drip system that is not so crucial, but the oil should be filtered for any particulate. There are many internet info sites on converting an oil burner to waste oil.

    My thoughts would be that a waste oil burner could be a good system for a larger forge, maybe even a welding forge, but probably not suitable for a small forge. Some sort of solenoid on the oil drip tube would be simple and add a safety fail safe that can shut off the oil flow with the flip of a switch ( just like all commercial burner systems are required to have).
    Keeping the oil supply tank away from the forge by a reasonable distance would be good safety.
    If used, the pre-heater should be well thought out and not capable of bringing the oil above 200F. It should never be something that you have to adjust manually in use to keep it from becoming too hot ( moving the coil closer or farther away, etc.), as we all know what happens when working on a blade...we forget almost everything but the blade and its shaping. What was running nicely at 200F 30 minutes ago could become a flame thrower if left un-adjusted, so that should never be a possibility in the design.

    Final comment. I have seen pictures of WOFs that were super simple. A #10 can with a copper tube soldered to the bottom with the tube coiled around the burner tube, and the end of the tube having a valve that controlled the amount of oil dripping into the burner tube. A fire was built in the chamber to get it hot enough, and the oil was dripped into the tube, running down to the chamber. Once the oil was burning ( really smoky in one video), the air was added to bring the whole thing up to running temp. When the burner tube got hot enough, the oil would vaporize when it dripped in and the forge would run like a jet engine. This may have worked, but is a nightmare of possible calamities. The worst is having nearly a gallon of warm/hot oil sitting 12" above a running forge.....just think about that for a second.


    None of the above is intended to dissuade anyone from building or using a waste oil burner, just to give food for though in design and operation of one.
     
    Last edited: Feb 15, 2014
  5. Bo T

    Bo T

    Feb 12, 2011
    I am interested in your build if you decide to pursue it. Would this forge work with animal fats as a last resort?
     
  6. David Stifle

    David Stifle

    Nov 20, 2008
    I may or may not build one, Bo, but if I do I'll post it up. As for animal fats, I honestly don't know.
     
  7. mete

    mete

    Jun 10, 2003
    Animal fats ? You'd have to render the lard or butter etc and filter, to get just the fat without water or solids.
     
  8. Bo T

    Bo T

    Feb 12, 2011
    Much as I have envisioned. Since it appears that you preheat the oil then the long chain triglycerides should melt. If the viscosity is low enough then it should be plausible. I know I have had some flare ups on my BBQ when cooking some of the fatter cuts of meats. In my mind it makes sense to try to design a waste oil forge that could use a full range of mineral, vegetable, and animal; oil, fats and waxes.
     
  9. Salem Straub

    Salem Straub

    Oct 20, 2008
    I hadn't seen this thread before. Let me add, for what it's worth, to not use waste oil of too high a viscosity. My experience with my waste oil forge was that using very thick used fryer oil was marginal in terms of ability to stay lit...

    I'd run one indoors only with a powered vent hood for the forge. It makes funky exhaust, even if you start up and shut down without a lot of smoke.
     
  10. JCP1969

    JCP1969

    343
    Jun 3, 2012
    Hello , I've not run a forge off used motor oil , I've run a furnace on used motor oil and used it for a molten salt pot, Its fine if there is no alternative . The problem really is getting the same type of used oil all the time. Collecting it from just anywhere is dangerous. You don't know whats been dumped in with it. Propane isn't safe if not vented properly. OIL IS MUCH WORSE. Oil needs a lot of oxygen to burn well . If you could build the forge using a muffle and use the radiated heat it would be much better. Then you could exhaust easily and have no open flame from burning oil.The muffle would have to withstand forging temperatures. How big a piece of pipe will you need? That could get expensive. What metal might work? It has to last for more than a few days fun. Propane changes with temperature which can need adjustment. Oil changes with every batch if the sources change. People always say there is nothing in it but used oil. I've found that usually isn't the case. Think ahead , this stuff really isn't for show and tell. They are tools that require the operators full attention. When I'm heat treating. I don't want distractions.

    I know this is off topic, but honestly this is why a blade smiths and I am not one. Never done it. Deserves their praises , they don't get there by being lazy or cheap. It cost money. Even if you have money it still takes conviction to play while some of that money goes up in smoke. Hopefully while some metal is being moved and your learning the discipline of the art.

    Good luck and be safe and enjoy what you do!

    James
     
  11. Gary Mulkey

    Gary Mulkey

    May 14, 2001
    :) A friend of mine likes saying, "Making knives is a lifetime of buying tools and then you die." So true.

    Using an alternate fuel like waste oil for a forge because it's cheap is A HUGE RED FLAG. I'm not saying don't do it. I'm just saying be safe. There are many very toxic fumes that can be generated by burning waste oil and you want your learning curve to be a safe one. I think that waste oil is probably a more viable fuel in a more contained environment where ALL fumes can be exhausted completely than in a forge.

    Also, I want reasonably precise temperature control in my forge which is one reason that I use propane. As has been said, used oil is a variable that doesn't lend itself to this easily.

    Gary
     
  12. oof

    oof

    634
    Jan 4, 2009
    I use an oil forge and love it. There are a boatload of different burners, but most seem limited in adjustment and perhaps more suited to foundry applications. I can't offer any advice on those as I've never had opportunity to use any of them. Mine runs on a siphon nozzle type setup. You can buy the nozzle and adapter for around $50, find a torpedo heater that no longer works and get your parts from it or if you have a lathe you can make your own easy enough.
    If you go with the torpedo heater like I did you'll find something like this inside. I've removed the combustion chamber in this pic so I could see how everything worked.
    [​IMG]
    I played around with keeping the igniter for a while, but found it's completely unnecessary and made the burner much larger than it needed to be. After removing all the unnecessary bits you'll be left with this, which is about what you will get for your $50 if you order your parts.
    [​IMG]
    I added a copper turbolator to give the incoming air some swirl and aid in combustion. The original housing for the torpedo had one built into the housing.
    [​IMG]
    Here's the business end after putting it in a piece of 2" black pipe. I drilled and tapped 3 holes 120 degrees apart to help center the nozzle in the burner tube.
    [​IMG]

    With the siphon nozzle I'm not too concerned about filtering my used oil. I have a 300 gal tank and 55 gal drums to pull my fuel from. If it sits long enough, most of the larger crap settles to the bottom. Plus the nozzle has a fairly large hole and will pass some pretty good sized chunks. On the rare occasion that it does become clogged, I can disconnect the burner, blow it out and have it running again in 30 seconds.
    [​IMG]
    As far as starting, It will light with a propane torch alone on a hot summer day. In the winter I thin the oil with a little diesel and it will light with the assistance of a few sheets of newspaper. I don't bother with heating the oil, but some guys do. A large coffee urn is a well used method. It maintains a constant temp with out supervision, and won't get hot enough to coke the oil. Heating the oil would do away with having to thin it.
    I haven't read of any other burner as adjustable as a siphon nozzle. from my understanding, pressure nozzles like the ones in home heating units are somewhat adjustable. however they rely on pressure for atomization so you can only turn them down so far, and that requires tools to do the adjustment. On top of that they clog very easily and require the oil to be filtered.
    The siphon works on air pressure for atomization. With a turn of the regulator I can turn mine down so it's barely running or I can shoot 3' flames out both ends. For general forging I have the regulator set around 5 psi or lower, welding 10 or 15psi. I also use a valve to adjust fuel flow.
    another thing to be aware of if you decide to order your nozzle is that they are rated for a certain gallon per hour. this is usually at 5 psi. It's nice to know but not that important for our use. for example, my nozzles are rated or 1.75 gph at 5 psi. if I turn the psi up or place the tank above the forge I use more fuel. I would never have to in my forge, but I could get it to burn 4 or 5 gallons an hour if I wanted. Which means the same burner would run a fairly large foundry or a much larger forge if I needed it to. I've never taken an exact measurement, but I guestimate I use .75 gph for general forging.

    There are a few safety issues to be aware of. the first being I've read there is a possibility of heavy metals being in your oil. Makes sense, as your engine wears most of the bits wind up in the oil. proper ventilation is crucial, but it's crucial with any CO producing piece of equipment. I have an 8' sliding door on the back of the shop, and the forge swivels out into the opening. It's not perfect, but works for now.
    Explosions, never had one nor do I worry about it. On the rare occasion the forge will flame out when it's hot, but not hot enough to self ignite. It will then produce copious amounts of smoke, and upon relighting with the torch will generally flash and burn all the hair off your forearm. I suppose there is the possibility of an explosion if you decide to go to the grocery store while the forge is running. If your standing at the forge simply shutting off the fuel will remove the hazard.
    Fires. You wouldn't have a gas can under your welding table so don't set one next to your anvil. same for any fuel source. Have fire extinguishers, enough said.

    mark
     
  13. JCP1969

    JCP1969

    343
    Jun 3, 2012
    Mark, what type of forge is this in? Vertical or horizontal, I 'd be interested in seeing what the fire box looks like , I wonder can you forge weld using the oil or are you strictly just forging to shape? Are you always working in the open flame or is this heating the forge at the same time? thanks for the info.

    Oh I see where you said you are welding. The oil doesn't contaminate the weld . I didn't know that motionless fan blade was called a turbolator. I have one in my fogger . I'm very interested . I have a large furnace / forge I built. I made it to pivot vertical or horizontal. I have yet to use it for anything .

    James
     
    Last edited: Feb 18, 2014
  14. oof

    oof

    634
    Jan 4, 2009
    James, at the moment it's in a horizontal forge. It pretty much looks like every other forge.
    This is a pic of it shortly after i built it. It's out in the yard, now it's mounted to the building
    [​IMG]
    It's "about" the same size as a 20 pound propane tank, maybe a little smaller in diameter.
    I'm just learning to weld, but I don't think there's any contamination. If I do what I should things work out for me....sometimes.
    Turbolator is a term used on a casting forum When they talk about burner designs. I don't know what else to call it, it fits.

    mark
     
  15. Salem Straub

    Salem Straub

    Oct 20, 2008
    oof, thanks for the post. I might try your design as it seems to work better than what I made. But it'll have to wait until this summer when I move the hot shop into the woodshed bay, close it in, and vent the forges through the roof there.
     
  16. JCP1969

    JCP1969

    343
    Jun 3, 2012
    David I hope I'm not hijacking your thread. I'm glad you asked the question. thanks

    Mark I like it. What I use for my salt pot furnace is the typical gravity fed in stream of air from small blower. It works vertical. The one pictured is going to get your modification if that is ok . I'll call it my oof forge. Its pretty big but I wanted to be able to shut it down and close it off for annealing . I built the door, it has an opening about the size of yours. Its a heavy door. I used clevises for the hinges. Its a heat sink too.:) I don't have a pic of it mounted . I will take some when I get her running with your setup.I made the lining out of crushed firebrick and fire clay, Little furnace the same. OH how does the ceramic insulation hold up to oil droplet ?
    [​IMG]
    [​IMG]
    this is just a vertical furnace its runs of oil . I do preheat with wood or propane til I can switch over to oil. I've sinced wrapped the gravity feed line around the furnace so it preheats the oil.
    [​IMG]
    Burning oil is ideal for me cause I don't drive a vehicle. I have had a propane forklift before and now its converted to gasoline. It was always hard to get the tanks filled. The large dealer didn't always feel like the weather was suitable for being outside or just nobody was capable of filling it. To much of a chore. twenty lb bottles I can deal with . exchangeable. But expensive for something that should cost only as much as regular gas.So I was told. So preheating with it is fine. Running like I just don't care , impossible. I would have to make some modifications for coal and then find it easily or its unreliable. Well oil is reliable for me. People have brought it to me for a few years now. I have a little stash.
     
  17. oof

    oof

    634
    Jan 4, 2009
    Salem, I'm glad you found the information useful. I can't take any credit for the idea, I merely looked at what others were doing and copied it.

    James, that thing looks like a beast. My only concern is the size of your tuyere. The burner needs to be in a pipe large enough that you can still get combustion air through it. Unless you plan on providing all the combustion air with the compressor.
    In the first pic of the burner the fuel/air hoses attached directly to barbed fittings coming out of the adapter. While the burner doesn't get that hot, after a short period of time the hoses deformed and would pop off. I removed the barbed fittings and replaced them with iron nipples to get the supply lines just a little farther from the heat. I drilled holes through the side of the pipe to allow the lines to attach there. Some have the lines going all the way out the back of the pipe. this would need a pipe that much larger to allow for everything to fit. The line on the right is fuel and the left is air for atomization. I use a separate blower to provide combustion air, and that comes in the back of the pipe via an old vacuum cleaner hose. a movable cover over the blower intake will also allow for finer control of your forge atmosphere
    [​IMG]


    The inner layer of my lining is a hodge podge of crushed soft brick along with some insulating refractory that the binder had gone bad, mixed with a little bentonite to hold it together. This is covered with a layer of noxram. I assume you are asking about ceramic wool? I don't think it would hurt it directly, but wool becomes fragile after firing and should be covered with a rigidizer. I don't think it will hurt what you have there at all, as long as it can handle the heat.

    The one thing I will warn about is that where the oil droplets impinge on the lining it will tend to coke up there. I have a metal hook that I occasionally have to reach in with and clear the tuyere. Most of it will come out this way, but there's always a little that stays and is hard as a rock. after a while I have to take a chisel to the opening to clear it back out.
    These nozzles can be had with different spray patterns. The ones I have are cone shaped.
    [​IMG]
    If or when I reline this forge or any future forge builds, I will make the tuyere opening where it comes through the refractory funnel shaped so that it opens up into the forge interior. This should help with the coking problem somewhat.

    mark
     
  18. JCP1969

    JCP1969

    343
    Jun 3, 2012
    Mark , I appreciate all this information. I have asked 4 or 5 people to keep a look out for a junk torpedo heater. I've had them but never thought they had much use when they started acting up. Heck by the time I got them they had been used for years in a manufactured home company to dry the dry wall compound.

    I will have to cut a whole through the side. I knew all along I would. Just wasn't sure of location and by the time I had crushed and mix my refractory I was thinking I would worry about it later. Its pretty fine grog I used and I have had some fires going in it , Probably burned a barrel of 1" oak blocks in it to cure. So I am hopeful I won't make a mess. All repairable though. I am thinking until I get the mixer. I may try and use a pressurized paint pot. It basically will act very similar at the spray gun end. I will have to play and see if I can manage to fit it in a pipe .

    When you talk about the carbon build up. I have not had an issue in my furnace but I do know what your speaking off. I had a brake drum furnace and I would have to chisel out the fire pan. Pretty hard stuff. Is yours collecting around the inside of the pipe right at the end?

    Well you have given me some hope yet. That is what I needed. I spent a few long days last summer trying the common drip method without success. I needed your insight. I went out yesterday , to tinker with her but it started raining. I did take a picture of my door. I will build the burner and see how she works prior to making any wholes. I will keep you posted, and man if this works out I will be tickled to death. thanks again David Stifle for asking the question. Mark thank you too for sharing.I will do the same.

    James
     

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  19. David Stifle

    David Stifle

    Nov 20, 2008
    I had forgotten about this thread, and thought it was long gone. I'm glad it was of use to some of you guys. I haven't done anything along these lines yet, but who knows...:)
     
  20. David Stifle

    David Stifle

    Nov 20, 2008
    Man! What a beast!
     

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