Jump to content
I Forge Iron

Simple Oil forge Build

Recommended Posts

I'm looking to melt some Zinc to make some sacrificial anodes for my boat. The zinc I have got is in bars and seems like it will need a fair bit of heat to melt it down given the weight and thermal mass of the metal.  The shapes are very simple and I intend to just press a sample into a tray of sand and clay and pour directly in. I can clean them up later and will mill a flat side and drill the screw holes afterwards.

I have been looking at many YT vids and doing some reading here and it seems like a simple oil burner will be the easiest and most appropriate thing for me to use as I get over 40L of oil from my boat every oil change and have over 200L stored up already.  From what I have seen on the net I can make a forge just from some ordinary house bricks and compensate any lack of insulation by just powering up the burner.  I have spoken ( emailed) a guy on yt who was very helpful and he suggested a pump on a PWM controller for metering the oil output.  I have got that and a pump and indeed the amount  pumped through is infinitely variable.  Just need to get a blower now and finish welding up the  gas bottle I'm converting to a burner and I'll be ready to go.

What I'm wondering about is what are the best and cheapest things I could line the forge with to stop melting the bricks?  This will pretty much be a one off build/ use so it does not have to be long lasting. The YT guy suggested a mix of builders clay, sand and some other thing I can't seem to get. If this glazes I'm not worried but is there any other cheap sort of refractory I can pretty much seal the bricks with? The YT guy did his loose at first but then sealed them with dirt and sand and said it worked much better to contain the heat.  I will do the same but wantto0 make a much larger forge to get a bigger crucible I have made into.

I was advised not to use cement as that can explode and does not stand the heat well anyway and will crack up but can it be mixed with anything?

Also, what is the melting point of Zinc? I believe it's somewhere between aluminum and copper.  I have seen oil burners melt copper ( and steel) so shouldn't be a problem but just wondering how hard I'm going to have to run this thing to get it up to temp?  I intend to make it tall and put the cruicible  a bit raised up so the flame goes under the bottom and heats the whole cylinder.

I have had an interest in this for a while and those burners look awesome in the heat and flame they can put out so if this goes OK, I think I'll look at maybe doing some other castings.
I can get loads of scrap aluminum for nothing * just have to melt it off the steel screwed into it)  and there are lots of simple things on the boat I could copy as well as maybe doing something arty!  :0)

Link to comment
Share on other sites

1: zinc melts way low 787 degF, 419 degC; Al melts 1220 degF, 660 degC; Copper 1983 degF, 1084 degC

2: I could dig a hole in the ground fill it with charcoal and stick a shop vac output through a black iron pipe to the bottom of the hole and have melted and poured before you could even get an oil burner cobbled together, much less working right.

3: learn how to melt and handle molten metal---much more dangerous than just hot steel even if the steel is 1000 degF hotter!

Link to comment
Share on other sites

Hi there Thomas, welcome George, please allow me to add the dangerous fumes of zinc while oxidising/melting, and to mention that aluminium/magnesium (old alloy wheels) scarify anodes are less dangerous to produce. It’s also depends on the water (sweet/salt water)  the boat is drifting on.

Last but not least, the material of the hull of the boat (steel or aluminium) depends the material of the anode (zinc or aluminium). Usually the casted in backbone of the anode (aluminium or steel flat bar) is welded against the keel bar next to the propeller and near the engine unit.

At your service.

Cheers, Hans

Link to comment
Share on other sites

Thanks for the replies.

Looks like it will be easier than I thought and I had things backwards.
Still want to build a flame throwing Oil burner. The things look so awesome and I'd like to give stump burning and shed heating a go with it as well.

You are correct Hans, Have to put a piece of steel in the middle. Figured I'd pour half the casting then let it cool, put the bar in after heating it up to drive off any moisture then put it on top of the bit I poured and do the rest.

Does anyone know how big a blower I will need? I want to be able to do something powerful but having a bit of trouble finding a jumpy castle blower round here.
What are the best ways to preheat the Burner? I have seen gas used and even sticks but is there some other trick to this I'm not aware of.  From comments I have read on vids getting the things hot seems the hardest part.

Thanks again.

Link to comment
Share on other sites

Nothing wrong in wanting to make a burner; it just seemed an unnecessary complication to get you from start to "boat in the water".

I've not worked much with zinc; will a cast adhere to a previous cast, or will you need to do a full pour?   I'm betting that a DYI boat forum can probably cover this better than we can...

Link to comment
Share on other sites

Thank you Thomas.

The burner is something I have wanted to do for a while and this is a use to justify the construction thereof and motivation to get it done.
If the anode is not right, no big deal, I got the zinc, a heap of it for nothing and figured this could be a learning experience many ways around.  I like the look of the simple brick furnaces I have seen on the net and the guy on YT I have been following  makes it looks easy and inexpensive to do.  If I decide I want to take it further I'll go to more trouble.

From what I have seen and asked, an oil burner is capeable of producing  enough heat to melt anything, even refractory and certainly seems to be the most powerful.  I don't know what sort of heat proper furnaces produce but the ones I have watched do 2-300Kw easily.  They sure look spectacular when they are getting a litre of oil a minute pumped into them.
I'd like to melt some scrap aluminum  which I have seen done just in a drum for separating the aluminum from steel parts which is the self same job I have.

I'll get the burner going and take it from there. No doubt I'll have a lot more questions I hope people can help me with as I go.

Link to comment
Share on other sites

On IForgeIron we push safety.  Did you miss the caution about old (used) motor oil being full of nasty stuff? 

How much volume of HOT liquid metal do you need for the pour? What is your plan B in case something goes wrong? 

Just because you can does not mean you should. Let me put it another way, you can recover from some injuries, but dead lasts a long time.



Link to comment
Share on other sites

Well my thought on that IDF&C was that any exhaust of what's in used oil would be a bad thing to breath and so should be done with 100% exhaust capture if indoors and great care taken with wind direction and neighbors outdoors.  The oil fired forges I have seen all were industrial and included forced ventilation aspects.

Link to comment
Share on other sites

While I wont go into how you heat the zinc this is how I would cast it after making sure the mould was properly heated before pouring in the metal. There is probably already stainless steel bolts welded where an anode has been in the past and this stops damaging the paint and antifouling of your hull if not you should fit some. Just be mindfull that too many anodes can be as bad as none as you have to have a ballance because you are basicly making a battery. The holes in the stainless strap in the centre are to increase the keying of the zinc and stop it coming loose and the strap just rests on top of the channel and the zinc will be held slightly off the surface of the hull Cheers Beaver


Zinc mold.jpg

Link to comment
Share on other sites

On 1/3/2018 at 8:59 PM, Glenn said:

On IForgeIron we push safety.  Did you miss the caution about old (used) motor oil being full of nasty stuff?

No, I read  that and all the other replys  thank you. I will be safe.
I have not worked out how much metal I'll need yet but I'll make sure if I miscalculate there is amply sufficient melted to make up any shortfall. 

As for the CO, I would not allow the combustion products from any fire ( or engine)  to escape into an enclosed area. That is just basic common sense.

Beaver, thank you very much for your comments and Diagram. I was in a couple of minds how to set this up but your suggestion looks excellent and the one I'll follow.  I was thinking of a different approach with round bar but I have a good amount of flat stainless I picked up a while back as offcuts from a factory dumpster and they will work with this very well.

I have mucked around with casting before and I always make sure to pre heat the molds very well. With the output of an oil burner that should be very  quick and easy.

Once again, appreciate the very helpful input!

So does anyone have any suggestions for something to use as a blower instead of a Jumpy castle type that is not too expensive but puts out good pressure as well as flow?
I don't know how to work out air consumption but Ideally I'd like something powerful enough to support combustion of at least 500Ml/ min of oil and up to 1L min.
Won't be running at that rate all the time but would like it when I want. the rest of the time I can either use a controller to slow the blower down or just restrict the intake.
I'm going to use a burner design that runs on excess air so fuel control is more critical than air control

Link to comment
Share on other sites

I have limited experience in this area, but I did run a waste oil forge for a short period of time before deciding it was more hassle than it was worth.  For forced air I used the blower from a power vent water heater.  That was marginal at best.  I also used compressed air to atomize the oil for better combustion and that created an air-inducing effect, but not enough to eliminate the blower.

500mL to a liter per minute seems like serious overkill to me.  For reference sake I was burning less than 4 liters/hour in the forge I built.  At work our shop has heated floors powered by a commercial waste oil boiler system.  The shop is large enough to hold two semi-tractor/trailer combinations and have room all around to work on them and store shop tools.  Lately our outside temperature has been mostly between -10 F and 10 F.  That system has been using about 20 gallons (75+ liters) in a 24 hour period, and that's with the large doors being opened several times a day to move trucks in and out.

There is a lot of energy in waste oil if you get complete combustion, but as already mentioned there are also dangers and hassles.   If this is just a "one off" type of thing I'd recommend a solid fuel fire.  If you plan to do a lot of melting for casting it might be worth your time and effort though.

Without knowing your location I can't offer better advice on a blower, but FWIW I did a quick search for "bouncy house blower" and came up with some as low as $40 US retail.  I didn't even look for used items.  

Good luck and be safe.

Link to comment
Share on other sites


Yes, 3-600Kw an hour should be a lot of overkill for a furnace but it would be fun for other things.  Should be great to stand around at a backyard party in winter!

I got a bounce castle blower off Fleabay that puts out a good gale and I'm going to either restrict the intake or use a PWM controller to slow it down.  Made a burner from a design on the net  but haven't fired it up yet.  I added a 2nd inlet so I can use one for gas for starting and the other for oil .  I think I'll try using a little pulse pump for oil feed and have a valve for controlling absolute flow and another for bypass so the oil loops.
The pump I have is rated to 4L / min which would be  way too much but if I can work up to that one day, should be something.

I thought of another use for the thing today with a bit of modification, a stump burner.  Just need to angle the flame down and I thought using some bypass air from the blower into where the fire is so as to make the stump itself burn not use all the oxygen burning the oil.

Might try for a test light up this afternoon.

Link to comment
Share on other sites

I found restricting the output using a gate valve to be better at regulating the air flow than restricting the intake. Either can work, but to me it seemed harder to get exactly the air I wanted by using a cover for the intake.

Sounds like you have a reasonable plan for oil flow.  I didn't have anything to regulate absolute flow, so everything from ambient temperature to depth of oil in the feed container affected the fuel flow rate through the siphon nozzle.  That resulted in a lot of constant fiddling with the air/fuel controls to keep the forge temperature somewhere near constant.  Then there's the nearly inevitable mess that dealing with used oil involves.  For me it was also a little difficult to keep a burn going on just used oil when starting up.  I tended to start up with diesel or kerosene for a few minutes and then switch over to the used oil after the forge chamber warmed up a bit.  The gas design should make that unnecessary for you.

Let us know how it works out for you and add a couple pictures if you can.  Stay safe.

Link to comment
Share on other sites

Well, That sure was fun!

Made some time this afternoon to give the burner a fire up.  Didn't worry about melting anything, just to try and see if the burner would Burn.
No worries there!

Started it off on gas and with a few powerful bangs that rattled the shed walls, she lit and sustained beautifully.  Paint burned off the gas bottle and I could just see it starting to glow red in the daylight.  Gas flow was pretty high.  hate to run one on gas as I think it would go through a bottle pretty quick.
I Started the pump, opened the valve, waited then  whoosh, off she went. Flame went from  blue which was hard to see to a bright yellow with a distinct increase in roar and noticeable radiated heat.
 Ran it like that for a bit increasing the oil flow till it looked like one of the burners I have watched on YT so many times. Backed off the gas and the thing just sat there breathing this 3-4ft jet of flame. xxxxxxxx awesome.  I sat there watching it for a while and it as like watching a stove. just sat there burning happily away.
I do have a couple of pinhole leaks in my weld I noticed which is annoying because it makes little puffs of smoke now and then.  Easy fixed though.

Was very stable  and I could control the flame then after a bit it didn't seem to matter what I did with teh oil valve.  I noticed the thing start to spit like sparks and realised they were oil droplets. The bottom of the burner  looked pretty cold but the top was really red by now and I could feel the heat radiating off the thing with amazing force. 
I Looked at the drum I was pumping  from and it was down a lot. I was calculating i must have used 7-8 litres and although I didn't know the time I had been running exactly, I figured maybe 15 Min, I'd burnt a lot of oil.  I read you can over fuel the things and the way to test was to turn off the oil and if the thing didn't back off in 30 sec it was flooded.
It sure was.

With no oil flow the thing was stable although doing a lesser flame than before.  I backed the air down and that didn't make a lot of difference although after a minute or 2, the thing seemed to pick up all on it's own.  I opened the air again and it started to take off really building and starting to run away. I thought something is going to happen here and it Did.
I got these huge backfires like shotgun blasts only like a machine gun.  Almost exactly like compressor stall on a flooded jet engine where they back fire. 

It's a bit like a deflagration. The  excess oil in the burner all tries to vaporise and boils at once and there isn't enough air so so it sort of flash backs.

Bet it frightened the Bejesus out the neighbors though but was awesome. Puffs of smoke and all.
After it cleared itself it settle and the flame began to subside.  I played with the oil again there and had pretty impressive throttle control just with the oil  and not touching the air.
I ran the thing a fair while and threw some old bits of ally in front of the output and it melted them real quick.  I can see why they say these things will melt anything.
I fired it into a stack of bricks I turned to it could blow through the holes like a big cat converter and in about 5 min they were all glowing  real well.
I spose I had it going about 45 min and burned maybe 21L of oil.

What I notced when I packed it up was the thing was perfectly clean inside. I expected heaps of soot and black crap but it was just the surface rusted steel with what I think was a little ash, light grey powder but not much.

I was really happy for a first fire up as lots of people say they have trouble with getting them going but the guy I have been messaging on YT said  don't be shy, if it flares up don't back off, give it the beans and it will be fine. and he was right.  they need to be started and run pretty hard till they heat up and can turn the fuel from liquid to gas to burn.

This burner has only 2" inlet and outlet which I think restricts max power. I'd like to do another one with at least 2.5" in and 3 out because the hot gasses going out should be more than the air going in. I'll also go from the 8mm oil feed to 12 MM which is the diameter of the pump outlet.  The guy on YT reckons a castle blower can do 1000Kw worth of airflow so would be interesting to try.

So next I'll do a couple more fire ups and play with the fire size and then make my furnace out of a stack of bricks and mud and put the burner in that and see how it goes.

Glad I got plenty of oil although it don't see like so much any more!  I'll be able to get rid of this stuff quick! :0)

Link to comment
Share on other sites

  • 1 year later...
On 8/29/2019 at 9:58 AM, ConstructionK88 said:

If this topic is open I do have a simple oil fed forge blower design I can give you. Reaches at least 2000f, is fairly efficient, easy to build or have built, and small.

I'd love to see your design.  I've spent quite a few hours developing an oil fired forge that works well.  A lot of trial and error. 

Link to comment
Share on other sites

I'm more partial to them myself. Not because of free fuel but the quick temp and yes still it's cheaper than most other fuels except charcoal (if you make it). I'd show a pic but a drawing for now. Think of it as a square paint can on its side. 



3/8inch thick 7inch long. Took about 15-20seconds to reach temp indirect of blower exhaust 


Edited by ConstructionK88
Remove download file
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...