Home Foundry

[100model]

or is diesel fuel really necessary?

Diesel fuel is not really necessary, you can use waste motor oil. In this video a simple waste oil burner is made and he melted lava so if he can melt lava he can melt cast iron.

 

[GreenTwin]

A few words of caution on using waste motor oil.
As mentioned in the video, waste motor oil contains heavy metals.
Is there enough heavy metals in waste oil to cause problems?
The video guy is just speculating, he has no idea what levels of heavy metals are in waste oil, or what level may be harmful, and I don't know either.

And sometimes folks use waste oil that has been contaminated by radiator fluid, etc., and this won't give a good or safe burn.

It should be noted that diesel combustion fumes are considered hazardous too, in spite of the fact that all diesel trucks on the highway burn it, and you drive behind them and breath the fumes.
You should avoid any fumes coming out of a furnace, regardless of the fuel type used.

The reason I don't like or use drip burners is that they have poor fine control, and tend to surge.
As ironman shows, a drip burner does work well for melting iron, so there is no question that a drip oil burner works well.
The beauty of a drip burner is its simplicity.
I still dislike drip-style burners, and will never use one (it is a personal preference thing, to each their own).

I use diesel with a spray nozzle because you don't need propane preheat with sprayed diesel; you just light it, and almost immediately you have full burner output.
2nd reason I like diesel is that it is relatively clean to handle, unlike waste oil which is very black and dirty to handle.
Both fuels are oily, but waste oil leaves black marks on everything ot touches.

3rd reason I like diesel is I can dispense it from any gas station that sells diesel into a gas can, and then pour that into my foundry fuel tank.
Or I can take my foundry fuel tank to the gas station and fill it there.

A reason I don't like waste oil is sometimes it contains globs of foreign material, and a siphon nozzle has zero tolerance for anything other than perfectly clean fuel.
You can filter waste oil.
If I used waste oil, I think I would use an inline spin-on auto oil filter.

I use a small automotive inline fuel filter just before my burner, and that is all I need with diesel.

The only downside I see with diesel is cost, and if you do a lot of metal casting, diesel could get expensive.
Some foundry folks use offroad diesel, and it is a cheaper fuel than automotive diesel.

Most mix 20% or so of diesel with their waste oil to thin it a bit, expecially in cold weather.

Diesel is impervious to cold weather, and I have started my siphon nozzle at 30F with no problem at all during either starting or operation.
And diesel is a consistent fuel, so you will always get the same burner output every time.
I literally never have to adjust my siphon nozzle burner. I don't adjust it before a melt, or during a melt, or between melts.
Diesel with a siphon nozzle and a fuel tank pressurized to 10 psi gives a rock-solid almost instant and non-varying burner output.


Propane has a lot of issues with cold weather operation, and the colder it is, the more problems you will have with propane.

And beware of the statement that "almost any oil can be burned in a furnace".
I have heard that burning hydraulic oil is extremely toxic (I have not verified this), so do your homework and don't burn something with known toxicity when it burns. This goes for any metal you melt too. Never burn the insulation off of electrical wires; those fumes are deadly toxic.

A buddy of mine uses waste food oil, from a fry grille, and with the right filtering, he says this works well for melting iron, if you can find a source.
I looked at using waste food oil, but these days they seem to have it all locked down like Fort Knox, and nobody wants to give anyone anything.
Waste food oil supposedly has a sort of french fry odor to it when it burns, which would be pretty cool in my opinion.


As fuel prices soar ever higher, we will probably all end up burning waste oil, just as a matter of staying solvent financially.
There seems to be no end to inflation these days, and it would be rather difficult to operate an iron furnace from the new"green" batteries that seem to be so politically correct now.

I think I would just add a spin-on filter if I convert to waste motor oil.
I always avoid breathing when I am near the furnace lid opening, so it does not matter if I am using waste oil.

I also have a powered respirator that I have used when trying to melt brass, to avoid the zinc fumes, but that is a pretty extreme solution.

.

 

[100model]

Waste food oil supposedly has a sort of french fry odor to it when it burns, which would be pretty cool in my opinion.

That is a myth that if you burn waste veg oil it smells like french fries. I have used waste veg oil in my furnace to melt cast iron and never noticed any smell. The same goes for waste motor oil it smells really bad when using a very rich smokey flame in my furnace.

 

[GreenTwin]

If I do start using waste oil, and it seems like that is becoming more likely with each day, I think I would preheat with diesel instead of propane.

It is easy enough to go get a 20 lb bottle of propane, but that takes perhaps 45 minutes to drive to the store and get an exchange, and I don't really have 45 minutes to spare.

I can buy 20 gallons or more at a time of diesel, and do that quickly.

I guess I would use a 3-way valve, and start on straight diesel, and once the furnace was hot, switch to waste oil.

If veggy oil did burn with a smell, I would insist upon Crispe Creme oil, from the legendary "hot donuts" place.
I think you could market Crispe Creme oil just for the odor, if you could get that same smell as cooking donuts.

.

 

[D and D]

Hmmmmmmmmmm - - - - that means that supply if I were to get into this would be problematic!
Local scrap yards only allow material IN - - - anything out is to the smelter only.
Absolutely NO sales of anything.

Brake disks are the go to for me.

 

[master53yoda]

I use waste oil for my scrap processing furnace, The 2 burners have a small (60,000 BTUH) adjustable propane burner built into the combustion air for the waste oil, the propane flame surrounds the nozzle for stable cold furnace ignition and shuts off when the furnace temp gets to the 750F manual to programed Control point of the oil firing rate.

The furnace holds about 200 lbs of scrap automotive engine parts, Depending on how much oil etc. is on the parts, I start and close the furnace but, if it needs more air for a clean burn I will fire with the lid open until the furnace and all the metal gets up above 400F or the oil has burned off the scrap. then I can close the lid. The actual melt time once the furnace hits the melt point is about 20 minutes. I am looking at increasing the 6" exhaust to 8" and adding more combustion air, The 8" will have a propane after burner to burn off any smoke that I get on the initial startup. The after burner will shut off at the 750F change over point. The initial 20 to 30 minute manual control deals with fuel/air variables caused by the oil on the scrap parts.

I use a 20 gallon tank that I pressurize to about 5 psi, the oil leaves the tank through an automotive spin on filter, I do use the high efficiency 5 micron ? filters, they cost about triple the price of a normal Fram filter but it does eliminate any particulate problem and they will last through 500+ gallons of waste oil , I have only changed it once in 4 years and that was due to a drum of oil that had water in it. To eliminate the water problem, when I start into another 55 gallon drum I pump out the bottom of the drum into another drum until I get only fuel. most drums have a few gallons of water in the bottom.

The oil runs through a pre-heater set for 150F, depending on what weight oil is in the drum, the heater provides stable consistent viscosity on the oil even below freezing temps outside.

The oil then flows through a 120 vac primary solenoid control valve then to servo controlled needle valves for firing rate control, I have override pots on the needle valves for control until the furnace gets above 750F it then is controlled based on the melt pool temp. it goes from full fire (6 - 7 GPH up to 1400f and modulates down to low fire (1 burner off and 2nd burner about .75 GPH) at 1475f. The control system uses an Arduino MEGA2560.

My burner atomizing air pressure is about 10 psi. using siphon type burners.

I will add some pictures from todays melt this afternoon.

 

[ajoeiam]

Ha ha haww. That is really funni! We have you completely fooled. I live in the Eastern part (actually central) part of the Soviet where it gets cold in the winter, but there is rarely a lot of cloud couver in the sky. I know because I do nite-time telescoping. Look on a map and you can find the Cascade Mts. which stretch from BC to N. California (actually further). Those mountains block the rain. Seattle has a bad rep for rain--and a certain time a year it is pretty bad, however, my nephew lives in Eugene, Ore, which I thimpfks if MUCH worse. Funny thing is Oregon does not get that rainy bad rep,but I thimpfks Ore. is actually worse. Ore. on IT'S Eastern side is also like the Soviet, far less rain, even a desert.

In the Soviet itself, as you approach Spokane, it starts to become wetter but not the type of area that has much fir, it is mostly pine which thrives in an almost desert like area. As you get into Idaho, you start climbing the 4th of July pass (or is that in Montana?) and you get lots of snow, don't know about rain. The people that live in the area (Idaho and MOntana) seem to like it.

Moses Lake, at one time, had the longest runway for fighter jets in the nation--it was SAC headquarters till '72, but the runway has been cut down now. The area is being considered for the HTOL space vehicle but it won't happen (me thimpfks) for two reasons: too much population and the weather HAS indeed become less sunny.

Well - - - so you're 'that' far east - - - grin!

Oh well - - - I like my garden - - - so I'll still pass on that offer - - - grin!

Sure wouldn't mind your scrap guys though!!!

 

[Richard Hed]

I use waste oil for my scrap processing furnace, The 2 burners have a small (60,000 BTUH) adjustable propane burner built into the combustion air for the waste oil, the propane flame surrounds the nozzle for stable cold furnace ignition and shuts off when the furnace temp gets to the 750F manual to programed Control point of the oil firing rate.

The furnace holds about 200 lbs of scrap automotive engine parts, Depending on how much oil etc. is on the parts, I start and close the furnace but, if it needs more air for a clean burn I will fire with the lid open until the furnace and all the metal gets up above 400F or the oil has burned off the scrap. then I can close the lid. The actual melt time once the furnace hits the melt point is about 20 minutes. I am looking at increasing the 6" exhaust to 8" and adding more combustion air, The 8" will have a propane after burner to burn off any smoke that I get on the initial startup. The after burner will shut off at the 750F change over point. The initial 20 to 30 minute manual control deals with fuel/air variables caused by the oil on the scrap parts.

I use a 20 gallon tank that I pressurize to about 5 psi, the oil leaves the tank through an automotive spin on filter, I do use the high efficiency 5 micron ? filters, they cost about triple the price of a normal Fram filter but it does eliminate any particulate problem and they will last through 500+ gallons of waste oil , I have only changed it once in 4 years and that was due to a drum of oil that had water in it. To eliminate the water problem, when I start into another 55 gallon drum I pump out the bottom of the drum into another drum until I get only fuel. most drums have a few gallons of water in the bottom.

The oil runs through a pre-heater set for 150F, depending on what weight oil is in the drum, the heater provides stable consistent viscosity on the oil even below freezing temps outside.

The oil then flows through a 120 vac primary solenoid control valve then to servo controlled needle valves for firing rate control, I have override pots on the needle valves for control until the furnace gets above 750F it then is controlled based on the melt pool temp. it goes from full fire (6 - 7 GPH up to 1400f and modulates down to low fire (1 burner off and 2nd burner about .75 GPH) at 1475f. The control system uses an Arduino MEGA2560.

My burner atomizing air pressure is about 10 psi. using siphon type burners.

I will add some pictures from todays melt this afternoon.

Whoa?! 200lbs? you must have a really nice setup to hold that much. I can barely lift 20 lbs without help. (I only weigh 98 lbs myself). You didn't tell me you live in the Soviet! Me thimpfks there are more HMEMembers in the Soviet than any other place. You should invite me to see hyour setup. I sometimes come out to Spokane to go to Costco as there is none in Moses Lake. I also invariably go to Alcobra on Freya ST.

 

[Richard Hed]

Well - - - so you're 'that' far east - - - grin!

Oh well - - - I like my garden - - - so I'll still pass on that offer - - - grin!

Sure wouldn't mind your scrap guys though!!!

Yes, I went there again today (actually yesterday by now) but with no $$, will get a check today and got some cast iron billets and some special iron, the type of steel that I got there before that I have needed and wanted since I bought it a couple years ago. They had some, it costs 35c / lb! More than the stainless! It is some kind of special stuff, it's the stuff that Genie makes their Genie bodies with. Whatever, I stashed it in a corner and will pick it up after work today. I thimpfk I will pick up more than I planned. The piece I need is 1-1/2 " thick, and that is what I found at tshe scrap yard. (Yay)

 

[GreenTwin]

I use waste oil for my scrap processing furnace, The 2 burners have a small (60,000 BTUH) adjustable propane burner built into the combustion air for the waste oil, the propane flame surrounds the nozzle for stable cold furnace ignition and shuts off when the furnace temp gets to the 750F manual to programed Control point of the oil firing rate.

The furnace holds about 200 lbs of scrap automotive engine parts, Depending on how much oil etc. is on the parts, I start and close the furnace but, if it needs more air for a clean burn I will fire with the lid open until the furnace and all the metal gets up above 400F or the oil has burned off the scrap. then I can close the lid. The actual melt time once the furnace hits the melt point is about 20 minutes. I am looking at increasing the 6" exhaust to 8" and adding more combustion air, The 8" will have a propane after burner to burn off any smoke that I get on the initial startup. The after burner will shut off at the 750F change over point. The initial 20 to 30 minute manual control deals with fuel/air variables caused by the oil on the scrap parts.

I use a 20 gallon tank that I pressurize to about 5 psi, the oil leaves the tank through an automotive spin on filter, I do use the high efficiency 5 micron ? filters, they cost about triple the price of a normal Fram filter but it does eliminate any particulate problem and they will last through 500+ gallons of waste oil , I have only changed it once in 4 years and that was due to a drum of oil that had water in it. To eliminate the water problem, when I start into another 55 gallon drum I pump out the bottom of the drum into another drum until I get only fuel. most drums have a few gallons of water in the bottom.

The oil runs through a pre-heater set for 150F, depending on what weight oil is in the drum, the heater provides stable consistent viscosity on the oil even below freezing temps outside.

The oil then flows through a 120 vac primary solenoid control valve then to servo controlled needle valves for firing rate control, I have override pots on the needle valves for control until the furnace gets above 750F it then is controlled based on the melt pool temp. it goes from full fire (6 - 7 GPH up to 1400f and modulates down to low fire (1 burner off and 2nd burner about .75 GPH) at 1475f. The control system uses an Arduino MEGA2560.

My burner atomizing air pressure is about 10 psi. using siphon type burners.

I will add some pictures from todays melt this afternoon.

Art B (masteryoda) has a heck of a nice aluminum scrapping furnace setup.

And he sells some really nice aluminum ingots too (I have quite a few of them).

.

 

[GreenTwin]

As far as melting iron using natural gas, I recall some converstations years ago about this, but it is all hazy now.

As I recall (check me on this stuff) you need a 2" gas line to your furnace.
Your natural gas regulator may or may not be able to provide enough flow to your furnace for an iron melt.
You may starve your other natural gas appliances if you put too much demand on your gas regulator.
You many need a higher flow and perhaps higher pressure? natural gas regulator.

I also recall reading about installing a natural gas generator at a home, and the things you have to do to make sure you have sufficient natural gas to feed it. Generally they put natural gas powered gensets very close to the gas regulator.

Hope this helps.
This is all I can recall.

I am sure natural gas can melt iron, but as with propane, you need a high-flow and somewhat high pressure regulator to get the flow that you need to melt iron. And you need a blower for compressed air.

.

 

[Richard Hed]

Well - - - so you're 'that' far east - - - grin!

Oh well - - - I like my garden - - - so I'll still pass on that offer - - - grin!

Sure wouldn't mind your scrap guys though!!!

Damn! Was at the scrap yard to pick up my winnings and was going to take photos so you could drool but I forgot. Was too excited to get the metal home. Want to take a small piece and see if I can harden it. If so, it will be even better for the project I have in mind for it. did I tell what that project is? It's a cross slide for the lathe.

Remember the older lathes (and the tiny hobby lathes today) used to have slots for mounting tools on the cross slide? They don't do that nowadays so I am going to build my own. Also, I am going to add a couple inches in length to it. Was hoping to be able to harden the project so I could grind the ways on it.

 

[GreenTwin]

One guy online broke up an old lathe for iron scrap.
He never lived that down.

One thing you don't do (apparently) is break up old lathes.
Something sacrosanct about old lathes.

Old machinery was typically made from gray iron.

Some have suggested weights, like you see at the local health place, but I have found the new ones to be of compressed metal, and not good for any foundry use. I am not sure about old dumbell weights. I have never tried to break one.

.

 

[master53yoda]

The residential Natural gas system is limited at about 600,000 BTUH ( 4.25 GPH diesel) that the meter will actually pass. In order to get that flow you need to have a very short piping run. Most NG utilities wont put a higher pressure system in residential.
On my furnace as I run the Propane through 1/4 lines Because of the line loss I need the 10 PSI that comes of the main tanks. I can get about 175,000 on my gas burners with an open line and using the line loss as an orifice. My burners have needle valves on the propane which allows me to vary the firing rate down to about 5000 BTUH when the burner is acting as a pilot for the oil.

On the scrap issue I end up with a lot of camshafts and I think they are mostly cast but I'm not sure

Art b

 

[master53yoda]

Here is a few pics of the furnace firing 1 with the furnace after the metal is melted, the other 2 are cold fire running about 60%, if i closed it this would have smoked due to not enough air.

Art B

 

[100model]

Green twin have you watched this video about a burner for cast iron melting? Hmmmmmm there was no cast iron melting and he sounded like a politician in election mode.

 

[GreenTwin]

Green twin have you watched this video about a burner for cast iron melting? Hmmmmmm there was no cast iron melting and he sounded like a politician in election mode.

I think I have touched on the "youtube burner guys" before, but it is worth noting again.

There are profession youtube "burner guys", and "ingot casters" (olfoundryman has some other terms for the ingot guys, which I will not repeat, but it has to do with polishing things).
It is not my place to tell people how to have fun, and so its all good as far as I am concerned, but not necessarily all good if you are trying to find a reliable foundry burner.

Generally speaking, the quantity of videos and view count for the burner and ingot guys is directly proportional to the usefulness of their content, ie: the more videos they have, and the higher the view count, the less useful it seems the information they offer is to a typical backyard casting person.

There also seems to be a correlation between the size of the flame from their burner and how useful the burner is, ie: the bigger the flame they are shooting out the end of the burner, the less useful it is for foundry work. A good foundry burner may not operate well at all if it is not inserted in the furnace opening (the opening in the furnace for the burner tube is called the tuyere, pronounced "tweer" I think).

There are a number of what I consider "junk" burners on youtube, and by "junk" I mean not useful for foundry work, or not reliable for long term foundry work. These burners may have other useful purposes.

How to tell if a burner is not useful for foundry work:

1. The burner tube gets red hot during operation. Red hot burner tubes do not last very long, even if made with stainless steel.
There is no reason to operate a red hot burner tube or burner for foundry work.

2. Used car salesman shrill pitches about burners that seemingly will do just about anything, including powering a Saturn V rocket are useless burners for foundry work in my opinion.

3. "Better mouse trap" burners are generally some unique twist to a standard foundry burner, to make a better mouse trap, but these burners in my opinion add useless gimicks to a burner that serve no purpose, and often give a burner that degrades over time. Some burner types appear to be outright dangerous, such as those using high fuel pressure.

4. High velocity burner outputs are not useful for foundry use. The high velocity flames just climb up the back of the furnace to the lid, instead of swirling around the crucible and transferring heat to the crucible.

5. BIG burners are not better for foundry use. I have tried some big burners, and they actually run cooler than the smaller ones.
The secret to operating a very hot burner and furnace is to introduce exactly the amount of combustion air and fuel into the furnace that a given size of furnace can completely combust, and making sure that complete combustion occurs INSIDE the furnace around the crucible.
Excess fuel and/or combustion air cools a furnace.
Bigger is definitely not better in the foundry burner world.

6. Burners that preheat the fuel like a Coleman gas stove burner does are not useful for foundry work. Running a fuel line through a hot part of the burner or furnace just cokes up the tube, and clogs it. There is no need to preheat fuel for a foundry burner unless you are running thick waste oil in the winter.

7. The Ursutz burner is what I call a "precombustion chamber" burner (not sure if that is an official term or not).
The Ursutz burner uses a chamber outside of the furnace, and the fuel is combusted in the chamber, and then piped into the furnace.
I have tried an Ursutz burner, and they get red hot when operating, and degrade quickly over time.
The Ursutz burner is reported (by someone who has used one a lot) to be easily capable of destroying crucibles due to producing too high a temperature inside the furnace, when the burner is operated at its maximum.
The Ursutz burner is also said to be capable of degrade the plinth quickly.
Given all of the problems that Ursutz burners cause, I can't think of any reason for using one for foundry applications.

8. It should be noted that some videos show burners that are not installed on a tangent to the side of the furnace, and thus the burner flames impinge upon the side of the crucible.
The crucible should never have direct flame impinging upon it, else it will fail very quickly.

BIG burner/BIG flame videos are great entertainment, but are not useful for foundry applications, in my opinion.

The burner types that have been demonstrated to work well for foundry work, that I have seen are:

1. The drip-style oil burner, which I hate, but others love.

2. The siphon-nozzle burner, or its cousin the pressure-nozzle burner.
I use a siphon-nozzle burner, and will soon be converting to a pressure-nozzle burner so that I don't need compressed air for atomizing the fuel.

3. The propane burner works well for aluminum melts, some brass/bronze melts, and even cast iron melts, if you have a high pressure/high flow regulator, and if your tank does not get so cold that it will not longer vaporize.
I use propane burners for aluminum only to avoid the cold tank/low pressure problem.

4. The Ursutz burner can I guess be argued about.
I know of one individual who has used an Urstuz for years to melt iron, and he likes it.
I would not go so far as to consider the Urstuz a good foundry burner, but I can't deny that this individual has melted perhaps a thousand pounds of iron (or more) using his Urstuz.
He has also had a lot of problems with his Ursutz, and problems caused by his Urstuz, which he just tolerates for whatever reason.
He sees lots of burner and furnace rebuilds which I think can be attributed to the Ursutz, which to me is totally unnecessary, and wasted time and money.

At the risk of sounding like one of those angry old gray haired guys who shouts at the schoolchildren "GET OFF MY LAWN !!!! ", I offer the following thoughts:

Rube-Goldberg style burners are not useful for foundry work, in my opinion, although they may be impressive to observe.
Many (perhaps most) burners on youtube are what I consider Rube-Goldberg style burners.
Millions of views, thousands of subscribers and likes, hundreds of videos, totally useless burners for foundry work.
Many burners on youtube are better classified as flame throwers I think, so perhaps they could serve some useful purpose.

.

 

[creast]

I often hear that you should never pour straight down the sprue, but this is indeed the method I use.

Most folks on youtube pour their metal with the crucible elevated some height above the top of the sprue (the sprue is the hole in the sand into which you pour the metal), and this should never be done.

The lip of the crucible should be as close to the top of the sprue as possible, to avoid a waterfall effect, which can entrain air and slag into the melt.

There should be a trap at the end of the horizontal runner, such that the initial flow of metal that contains air and slag has somewhere to go before metal begins to enter the mold cavity.

The sprue should be sized so that it fills very quickly, and remains full during the entire pouring process.
If the pour is interrupted for any reason, you will aspirate air down the spure, interrupt the mold filling process, and generally ruin the casting.

The sprue should transition smoothly from vertical to horizontal, to prevent turbulence in the metal.

Turbulence anywhere in your sprue/runner/gate/mold system will churn air, slag, bifilms, and often mold sand into the casting, causing defects.

I generally use a 3" diameter short length of steel pipe (perhaps 1" long) at the sprue, just to catch any initial spill from when the pour starts.

You can practice pouring water from a container into a small opening or basin, and try to keep the sprue full, minimize splashing and turbulence, and avoid the waterfalling. Pouring metal from a crucible into a sprue is a bit of an art, and you get better at it as you go.

Ironman (luckygen1001) has excellent pour control with minimal spill, most of the time.
Watch his videos to get an idea of good pour technique.

.

We all find out methods.
Luckygen and olfoundryman are my heroes too but Martin would disagree about pouring basins and has stressed the importance of them when pouring aluminium.
Cast iron is a different fish I guess.
I know he has also criticised extended sprues but I note he has also used them.
As you know, I have broken accepted methods to achieve a result and I think aluminium has to be treated differently due to its oxidation during pouring.

 

[GreenTwin]

I have studied myfordboy's methods, and he has great success with aluminum, but often does not use runners and gates in the same fashion I do.
Myford gets great results, and so it is tough to argue with success.

Aluminum melts easily, pours easily, flows very well, and is easy to get a good surface finish with, especially with petrobond.

With the backyard version of "lost foam", which is not the same as the industrial version of "lost foam", I have seen mixed results; sometimes pretty impressive results, and sometimes very rough results, with aluminum.
The backyard "lost foam" with iron is a disaster, from what I have seen, and the industrial method needs to be followed for that to work.

I have not dabbled in investment casting, so I can't really say what does or does not work well.
I have seen some pretty impressive results with aluminum (see creast's thread).

I like to watch anyone's casting work really, with the hope that I can always learn new tricks and techniques.

And I like to play with fire, so there is that.
The "danger-factor" makes it pretty exciting.
The pours where I don't kill myself are especially pleasing.

I like the model engine hobby, but I REALLY like the model engine/foundry hobby !
One of the more fun and interesting things I have ever done.

.

 

[Richard Hed]

I have studied myfordboy's methods, and he has great success with aluminum, but often does not use runners and gates in the same fashion I do.
Myford gets great results, and so it is tough to argue with success.

Aluminum melts easily, pours easily, flows very well, and is easy to get a good surface finish with, especially with petrobond.

With the backyard version of "lost foam", which is not the same as the industrial version of "lost foam", I have seen mixed results; sometimes pretty impressive results, and sometimes very rough results, with aluminum.
The backyard "lost foam" with iron is a disaster, from what I have seen, and the industrial method needs to be followed for that to work.

I have not dabbled in investment casting, so I can't really say what does or does not work well.
I have seen some pretty impressive results with aluminum (see creast's thread).

I like to watch anyone's casting work really, with the hope that I can always learn new tricks and techniques.

And I like to play with fire, so there is that.
The "danger-factor" makes it pretty exciting.
The pours where I don't kill myself are especially pleasing.

I like the model engine hobby, but I REALLY like the model engine/foundry hobby !
One of the more fun and interesting things I have ever done.

.

I want to know about the pours where you DID kill yourself. How did they work out?