Before starting the smelter was modified, reducing the internal diameter a little by lining the inside with mud. It seemed to improve performance.
The first run of melted cans worked well. But somewhere during the second run aluminium leaked out and pooled down the bottom. Slag has now jammed up the crucible which is no longer usable.
From talking with some friends on IRC it appears the crucible was
overheated and the aluminium formed an alloy with the steel causing it to
fail.
The target temperature we want is around 650 to 800C, no hotter than about
bright red I think. I think we had it to bright yellow which is apparently
1100C+ according to internets.
So maybe lower air flow to keep the temps down and/or isolating the fuel
from the crucible.
I’ve been doing casting for awhile. Have a slightly different approach. Crucibles are a constant problem - proper crucibles are expensive and have to be treated with due care to avoid thermal shock, etc. Should also use a separate crucible for different metals. Also, coke is a cleaner heat source than coal, though charcoal has been successfully used for lower melting point metals. I use propane with home-made refractory and a home-made burner and I use greensand moulds with sand/silicate cores. Would like to be able to do cast grey-iron but it’s difficult to work with in a home setting.
I’ve attached some pics - not in order. Furnace, pattern for the mounting for a tool-rest for a wood-lathe, casting straight from mould with sprue still attached, mostly finished casting, burner under test, furnace and top, temporary crucible.
G’day Ian,
I’ve been contemplating going over to MHV to have a squiz for quite a long time but never seem to find the time to do so. Casting related topics have come up a couple of times over the past few years. Do you think there might be a bit of interest in a show and tell type thing some time? I’m definitely not an expert, and it’s the sort of thing that’s covered quite well on the internets, these days, but it never hurts to take a closer look;)
Cheers, Chris.
Yes!, That would be cool.
I wasn’t sure from you message are you thinking that I show and tell or you show and tell?
I have very little experience, other than the internet this post and the internet.
A session similar to what @clixx_io did the other week would be ideal. Just an informal gathering Saturday morning, $10 per person to cover coal etc (rest to MHV), possibility to order pizza for lunch, If 8-10 people where interested would be ideal. With a basic plan to cast something simple.
Currently at the space there is a furnace / chimney thing. and a bunch of cans. @jambulance has a better crafted bucket furnace and crucible.
What we don’t have is a good mold or much molten metal related safety equipment.
Hi Ian (My name is Chris;))
I have a few things I’d like to cast for a current project. I need to make up the patterns but I think I could arrange to bring along some stuff and give a demo one Saturday morning, if it could be of benefit to your members. It usually takes me a couple of hours to ram up a mould. I use gas in a home-built furnace but happy to show how I built my furnace, burner and forge. (Ummmm - not sure how work-cover would view my efforts:D )
I’ve seen a few questions over the years, though, and I half-completed a foundry course some years ago. I’d really like to be able to work with Iron but that’s a whole other story - too dangerous to work alone, I think, with Iron. As for Aluminium, ZAMAC, and possibly even bronze, these can be done in a home foundry.
One of the patterns will require sand cores to be made. I can make these ahead of time but I can show how it’s done as it might be of interest to HMV members.
Come in and see the space! Get an idea of what we have and the area to work in. Tuesdays or Wednesdays are best. Sadly I don’t think I will be free tonight, but other people usually turn up from 7. If that doesn’t work for you let me know and I can open up some other time.
Lets get an expression of interest from other members, I would like to see a few people, say at least five, better ten, put there hand up.
Pick a date that suits you, perhaps in a 2-4 weeks so people can schedule there time.
Other planning,
Can you advise what kind of safety measures will be needed? - Will everyone need protection or just people close by?
What are the key things to communicate on the day? - Eg it sounds like the mould making is more involved than I realised.
Is there resources / equipment that we need to arrange beforehand?
I will start by making a new post for interest from other members, and talk to the committee about other channels. Let me know if you would like me to open the space at a time convenient for you.
Hi Ian,
I’ll aim for that date and time. I need to finish knocking up a small pattern for a casting that I need for a project. I shouldn’t need help with transport/setup but I’ll drop by sometime beforehand so I can see the layout of the space. My main concern would be how close I can park 'cause some of the stuff is heavy and it wouldn’t be good to have to drag it any distance.
There’s a few different techniques that are used in greensand moulding. I’m thinking that I could knock up an `odd-side’ mould - it’s not a technique I’m particularly good at, or happy to work with but it’s one that is useful, none-the-less. I could do a smallish casting and bring along some examples of things that are used for more complex castings.
As with any process where heat and fuel are involved, there are always some dangers involved. Fumes are always a thing to consider - particularly if you do any sort of casting on a regular basis or on a large scale.
Cheers, Chris.
