Discussion in 'Furnaces and their construction' started by Barry Booth, Jun 30, 2020 at 8:38 PM.
Yes the stuff is pretty amazing. Wrapped with a couple of inches of kaowool is all you need. Worth EVERY PENNY!
Jason, I have never found anything better. After years of use, not a crack in it, its vetrified (melted) on the surface but with no damage at all! My furnace has wall thickness of 2" and no kaowool just pure cast Mizzou and the paint on the outside of the furnace hasn't even burned off! If anyone has found anything better please let us all know...
Yes Jason, worth every penny and then some! Anyone else use Mizzou?
Many of us have mizzou setups. However, there is a certain card carrying radical nutjob group here that have rebelled, swallowed the koolaid, sold their souls and now have straight kaowool furnaces covered in satan shit.
It makes for a very lightweight setup and is pretty decent. I built a glass glory hole rig like this. It heats lightning fast and is dirt cheap to build. It is kinda of fragile and will need a maintenance coat of satanite at some point in the future. I still like my tank of a furnace, it's tough, needs zero maintenance and hasn't cracked. Mine is on wheels and is portable enough for my needs.
The best part with this new school of thought is it cuts down on shipping heavy ass bags of refractory. I got lucky and picked mine up just a few hrs away by car. Not everyone is so fortunate.
Very interesting Jason, my furnace is portable and can be easily picked up and moved even by a old fart like me. I had a local Mizzou dealer but they are gone now and yes shipping drives the price way up so I can understand their thinking. I bought enough to build two furnaces but by the way the first one has held up I don't think I'll ever need it.
Its good for the everyone when people branch out and try new tech materials because it advances the art of foundry work, I applaud them!
Ive got an inch of Unicast-70 (a dense castable refractory that performs similar to Mizzou based on all I've put it through) backed up with 2" of ceramic fiber blanket insulation in my big waste oil/diesel furnace. It works great but it is bigger than I need most of the time, and even with the insulation that inch of dense heat sink takes a lot longer to heat up than my smaller ceramic fiber blanket and satanite propane furnace. I've really only used the small furmace since I built it, but when the time comes when I need to pour something bigger or do several back to back heats, that's when I'll most likely break out the big old heavy duty furnace again.
Very interest Jeff, you have the best of both worlds! I look at it this way, there are numerous refractory materials out there and based on your location a select few have distinct advantages as to price, shipping costs and availability. Metal founding is centuries old and what is available locally or at a lower cost elsewhere is key and the smart way to go.
Barry, welcome to the forum! It looks like you have some really good burners and furnace set up. What were you melting in those pictures? Were you using insulating wool at the time?
Thank you Matt, very kind of you and so glad to meet you!
In the picture I'm casting AL. replacement parts for an antique drafting table. They had a very distinctive shape which I machined from the cast parts. They turned out well with no porosity or inclusions and machined beautifully. And to your question no insulating wool was used. I also do cast iron (model loco parts) and bronze hence the steel cope & drag.
I like your feed system. the right direction to avoid porosity. Did you get any shrinkage on the flat areas?
I've used Greencast 90 which is good for a little higher temperature than Mizzou but there's really not much practical differences in refractories for tiny furnaces like we use. The biggest issue is keeping steel away from the high temperatures, including areas of gas leakage. My brick furnace has just over 450 melts on it with 2,600F brick which takes a beating during iron melts. The advantage of lightweight refractories is the speed of furnace warmup. I like brick because it requires no dryout and is quick to build and repair.
I don’t cast aluminum, but I do look at many of the posts related to it. I thought the consensus was that the optimal mold filling direction was supposed to be bottom up. Exposing my ignorance here, I guess. But that’s ok.
Does look like a nice casting, for sure.
Hello oldironfarmer, very minor shrinkage, the pattern had extra volume for finish machining but very little was needed, I lucked out.
450 melts! Wow you're a busy beaver for sure! My furnace has held up very well thankfully, what really takes a beating is the graphite crucibles. They don't last long melting cast iron, the erosion is excessive, ugh. I've been toying with the idea of building a cupola furnace, we'll see...
Denis you're quite right about the pour direction. It was my inexperience and misconceptions that guided me, if I had to do it over again I would change the pattern, I lucked out. Why I think it turned out so well was because the side lugs acted as feeder wells.
Good point! I was ignoring after the gates, just that he has a surface pool and a weir. While the sizes aren't great the finished product is what's important. Agreed that casting it upside down to what was done is preferable. Put all the pattern in the cope and the gates in the drag.
Like all of us guys I'm learning and just simply lucked out. That's why I joined the site to improve my skills by learning from you! Life would be so boring if we didn't "F" up at times and learn by our mistakes.
Separate names with a comma.