Poured some metal yesterday, attempted cast iron. I cast this part in Al to see if I could make a good part. Succeeded in Al. So thought I'd try iron. Only melted iron once and just to see if I could. I'm sure the iron was too cold, but what did fill was nice. Broke sprue and runner, nice gray iron. Was burning propane, I'm sure I'd have better luck with oil, but I'm still working some things out for oil. This part is for my Kalamazoo 610 horizontal band saw to mount a table to use the saw vertically.
Good to see that you tried cast iron for the first time! Any more attempts in the future? These are two of the biggest hurdles for a beginner to cast iron, 1. getting soft cast iron, 2. getting your cast iron hot enough to fill up the mold. It is good to see that you only have one to cross (getting your hot enough to pour). I had both those hurdles when I first started to melt cast iron and took a while to overcome them as there was no internet then. This is how I know when cast iron is hot enough to pour, after scraping all the slag off the surface of the iron it should be very shiny to look at and if the slag keeps forming on the surface it usually means the iron is not hot enough to pour.
If not for forum members like yourself and all the other veteran metal casters who so freely offer there knowledge and experience, guys like me would be hard pressed to do any of this. Yes I plan on giving it another shot. I have oil set up for my furnace but I think I need more air, it just doesn't burn like it should. I'm using a small shop vac now and its maxed out, I have a leaf blower that I'm going to adapt to my set up and hopefully that will give me the needed boost. Thanks for the tips and encouragement.
Dave, You might possibly need more air. But, it is good to remember that the most common reason for poor iron melting it too much air. If you can post up a vid of your next melt, you might get some feedback on the question. I think that the optimal fuel burn rate for my 14" bore furnace is about .18 to .19 liters per minute and the flame coming out of my chimney should be just faintly visible against a shaded tree background and not visible against the sky. It is also easy to push too much fuel and air through the furnace in the right ratio but not fully combusting in the furnace. I like having a good fuel flow meter on the line so I can know where I am. If one is guessing about fuel flow rate and guessing about air flow, that is too much guessing for me. Lately I've been melting 70 pound batches of iron and each run has been plus/minus 1 liter total of 24 liters and very close to 1 hr and 55 minutes. Probably not record setting by any means, but I love the idea that I can tune my furnace to the same settings so closely and get consistent melt times and temps. I measure my melt with an immersion pyrometer tip and a homemade readout and pour at 2550 F. I agree that it is possible to learn what hot iron looks like and the shiny melt surface mentioned by Ironsides has also been pretty good for me. I also note that the iron is roiling at 2500 or so. I do like measuring things though. Denis
Thanks Denis for the input, but I'll probably be leaning toward guessing, I'm only melting an A6 full of iron for the part I want to make. I'm sure if I were doing things on the scale that you do I would want to be more precise. Trial and error will do for now. Thanks.
I did not mean to put you "on the apot", Dave. I guess my answers to questions are directed to the person asking, but I realize that many of us read through threads to see what is being talked about. So, I direct my answers to both the person who actually asked the question, but also to someone else who may be reading it. I was speaking more about my personal philosophy rather than necessarily what you personally should do. This is especially true if you expect to melt iron only occasionally and do not mind some inconsistency in your melting outcomes. Denis
When I first started melting iron a 850 watt vacuum clear was used and worked OK but on hot humid days it would struggle to get really hot iron for thin castings. One day I used a larger crucible and the iron took forever to melt (lots of failed castings in this pour) so it was then I realized I needed a larger vacuum cleaner (1600 watts). Since then hot iron has never been a problem with a bigger vacuum cleaner. A lot metal casters watch my videos and try to melt cast iron with their furnaces so they complain to me that their furnace will not melt cast iron or will not get the iron hot enough to pour. From what I can see in their video is that they melt aluminium but what they fail to understand is getting to iron pouring temperatures so much more fuel and air has to be burnt so this will happen. I use three different sized crucibles in my furnace so the smallest one uses a lot more fuel per minute than melterskelter does. The middle sized crucible uses 0.18 liters per minute and the largest crucible uses 0.17 liters per minute. Using the smallest crucible I have to careful not to overheat the iron as the furnace is only melting less than half the iron that my middle sized crucible melts. I used propane for many years to melt iron and it worked really well so I had to pay for propane but waste oil is for free.
Ironsides, It is interesting that, though separated by 7000 or 8000 miles and working quite independently, we have converged on such similar burn rates. I am burning diesel, of course, and you WVO (I think or is it wste motor oil?) which has a slightly higher energy content than diesel, but still, remarkably similar burn rates. I suspect you came to those rates by simple trial and error as did I. It suggests that those are data points that new melters might consider as resonable starting points for their own operations. Obviously furnace design variations, altitude, and temperature will all affect the ideal setting. But as a place to start... Denis
I use a low tech method, use a clear plastic container and place it on a scales then weigh 1000 grams of water. Mark on the container to what the water level was and tip out the water. Put the plastic container on the scales again pour waste oil mix until it is the same level as the water was and see what the weight is. I then weigh the oil tank before melting and after melting to see how much fuel I have used so then I can convert the weight into liters. It takes 55 minutes for a melt and divide 55 by the the amount in liters and you have liters per minute I use waste motor oil, 80% waste motor oil and 20% diesel. As I live near a snow ski resort cold days requires in winter a 30% diesel mix. My iron melting furnace has a inside dia. 355mm and is 380mm tall.
If you like low tech, before I implemented the flow meter linked above, I would put my 5 gallon supply can of fuel on an electronic scale and observe the weight change over 5 0r 10 minutes and calculate flow rate. The trick was that even decent electronic scales made discerning .01 or .02 L/minute flow rate changes difficult. And each tweak required a time delay to try to see how much the flow rate changed. But, at least you could get a rough idea of where you were. You might be wondering if you really need to discriminate between .18 and .20 L/M flow rates. In my foundry it makes a real difference in furnace performance. So, trying to get a real-time handle on flow rates is worth some effort IMO. There are other possible strategies where you could have a 1 or 2 liter graduated cylinder incorporated in your fuel line and one could periodically fill it and observe the rate of depletion. That would likely be more sensitive than the weigh method. And using a smaller cylinder would increase sensitivity at the expense of convenience. One could have two lines feeding the furnace arranged on a "T." One branch would feed straight from the tank and the other could feed from a small graduated cylinder. Periodically switching from tank to cylinder would allow flow rate measurement. That would be about as low tech as it gets. Denis
With all the variables that can have an effect on the fuel rates ...burner design..furnace design..air flow rates...chemical composition of fuels..altitude...atmospheric pressure...humidity...sooo many more I didnt list...yet you guys are almost identical in fuel consumption rates! Thats freaking incredible! If anyone wanted a place to start that would be a good place.LOL
