A while ago the discussion came up about if you burn waste oil you need more space between the crucible and furnace wall to burn oil to get the hottest flame. With propane you can get away with less space between the crucible wall and the furnace wall. With my furnace there is a 75 mm (3") gap to burn waste oil and it works really well. So I watched a video from a former AA member and his furnace has a 25mm (1") gap, so is that too small and what is the best gap people should use ? He melts iron and pours castings so maybe that gap is enough. It is great to see that others are putting their iron melting adventures on youtube. To see the furnace gap have a look at 5:51. If you are interested in iron melting the whole 40 minute video is good viewing.
Yeah, but it's Chirpy! God only know what he burns! I love watching him fart around in the machine shop barefooted. He came here when AA was still limping along and then he decided he didn't like it here. Not sure why, but I wish he'd come back.
I have a 1" crucible gap with a 1/3rd larger furnace than Chirpy's and get mixed results, with a couple of good melts in the 30-45 minute range. Going to a 2" gap would more than halve the speed of the combustion going past the crucible and help heat the crucible I think. Still working on the settings for a reliable run. The simple proof for me would be to buy an A16 crucible instead of the A25 I use and see if the increased gap helps things.
I am not sure why you are having mixed results as chirpys gap is 25 mm and it works well for him. There seems to be another factor as to why you are getting mixed results as the gap can range from 75 mm to 25 mm and it still works well when melting iron.
