Miras Absar Posted July 31, 2013 Share Posted July 31, 2013 After using a charcoal foundry for a bit I've decided to go propane. I've already done some research and have most of the stuff figured out, I just want to see if anyone has any other suggestions for me. As for refractory I will be using a mixture of sand and fireclay (2:1 by volume). The crucible I'll be using is an A2 (3.75" diameter). I'll have 1.5" on both sides and a wall thickness of 2" so the entire foundry will have a diameter of about 11". I'm going to be melting mostly bronze, brass, and occasionally aluminum in the foundry. Any suggestions, am I missing anything? Thanks =) Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 31, 2013 Share Posted July 31, 2013 A more insulative refractory will save you hundreds of dollars in fuel over it's life Have you inquired over at backyardmetalcasting.com? Quote Link to comment Share on other sites More sharing options...
Miras Absar Posted August 1, 2013 Author Share Posted August 1, 2013 Will do, I may use kaowool instead of a homemade refractory. Thanks! Quote Link to comment Share on other sites More sharing options...
Joe111 Posted August 18, 2013 Share Posted August 18, 2013 The kaowoll wont last long. Insulated refractories will be in the $500-600 range for that size furnace or more. Also furnace atsmophere is very important. Most lightweight refractories don't like reducing atsmopheres. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted August 18, 2013 Share Posted August 18, 2013 ? The kaowoll wont last long. Insulated refractories will be in the $500-600 range for that size furnace or more. Also furnace atsmophere is very important. Most lightweight refractories don't like reducing atsmopheres. wont last? expencive? using an over coat of refractory makes it last very long, so do not use the inswool, etc, wiht the open exposed fibers. Risk of breathing the fibers themselves are good reason not to, plus the covering of refractory prolongs the life like you wont believe. Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 19, 2013 Share Posted August 19, 2013 The kaowoll wont last long. Insulated refractories will be in the $500-600 range for that size furnace or more. Also furnace atsmophere is very important. Most lightweight refractories don't like reducing atsmopheres. I have to wonder where you buy ceramic wool refractories. I live in Alaska where everything has serious shipping tacked on and could line that furnace with a couple inches of Kaowool for say about $30, give or take. Kaowool loves a reducing atmosphere, heck it's an industry standard foundry refractory. The fibers are a health hazard but can be encapsulated with a kiln wash like ITC-100 though there are less expensive alternatives. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Joe111 Posted August 19, 2013 Share Posted August 19, 2013 The point was long term expense. Hard refractory vs insulating refractory. Price was for castable refractories. He will have many heat cool cycles. That is the nature of founding. The hard refractory will last him a decade if he dosent break it. The insulating castable will last only a few cycles before it spalls and need to be repaired. Insulating refractories by their nature are porous. this allows gasses to enter and attack the oxides and reduce them to their base metals. A fuel fired furnace needs to be restrictive in gas flow. The heat needs residence time within the furnace for it to be efficient. Most crucible furnaces are designed with a exhaust port that will flow 50% of the required gasses at atsmopheric pressure. Some flow even less. That plus the permeable nature on the insulation leads to gas flow thru the insulation. This leads to deterioration of the lining and low insulatining efficiency. The ceramic fiber is a bad choice all around for this application. Don't get me wrong, I use it and like it a lot. But it has neither the required resistance to reduction nor the mechanical strength to survive in a fuel fired crucible furnace as a hot face refractory for much time. You can coat it all you like but you wont make it airtight. The surface wont decay but the interior will. Just ask yourself how many times you hit the lining with tongs? it will rip the fiber or crack the coating. Both will cost you money. Another aspect to the hard refractory is its nature to store heat and release it in the needed range. Instead of the heat going out the flue, it is radiated directly into the crucible. resulting in a large savings in energy. Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 19, 2013 Share Posted August 19, 2013 Where did you acquire your experience? While I'm not more than an occasional caster I've worked with ceramic wool lined melters since jr. high school. We don't use tongs that will hit the lining. Currently the only melter I've been around that isn't lined with kiln washed Kaowool is a cupola. So, no I'm not a "caster" but I've been doing it off and on for more than 45 years, been building furnaces that produce temperatures far in access of those needed for bronze casting. My propane forge produces a reducing atmosphere, the washed kaowool lid liner is more than 10 years shows no deterioration. Based on personal experience, research and that of personal friends outside of those on IFI I must ask you to provide cites as I find your statements without credibility. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Nobody Special Posted August 20, 2013 Share Posted August 20, 2013 Reducing atmosphere helps a lot with copper, bronze, etc. What's the setup you're planning on your burner? Naturally aspirated? Weed burner? Multi burner? Flamethrower? Are you green sand casting? Using investment? Lost foam? Did you already put it together? If so, hows it working? Pics please! Backyardmetalcasting has a decent homemade refractory, it worked for the small scale casting I did...took to using wool underneath on later furnaces, saved time. If it get's REALLY hot, the portland may slag some. It occaisionally spalled a little, but then again, it was cheap, and it didn't take long to repair either. Setup depends, is it gonna be a once in awhile hobby? Or something you're doing on a regular basis? (dang it.....now ya got me missing it, may go look for some pipe, my regulator and something to use for an outer shell......) Quote Link to comment Share on other sites More sharing options...
Joe111 Posted August 20, 2013 Share Posted August 20, 2013 Where did you acquire your experience? While I'm not more than an occasional caster I've worked with ceramic wool lined melters since jr. high school. We don't use tongs that will hit the lining. Currently the only melter I've been around that isn't lined with kiln washed Kaowool is a cupola. So, no I'm not a "caster" but I've been doing it off and on for more than 45 years, been building furnaces that produce temperatures far in access of those needed for bronze casting. My propane forge produces a reducing atmosphere, the washed kaowool lid liner is more than 10 years shows no deterioration. Based on personal experience, research and that of personal friends outside of those on IFI I must ask you to provide cites as I find your statements without credibility. Frosty The Lucky. Been doing this since I was 15. Im 72 now. I own foundries and mills on 3 continents. But you are right. I know nothing. :D If you want certs, look them up yourself. Anyone with a simple knowledge of chemistry will realize that metal oxides in a reducing carbon laden atsmophere is a really bad idea. Look it up yourself in Ijera or jstor or springerlink . You will probably even find some of my work there. :D I see with 10,000+ posts, you have plenty of time for hands on work. Lots of experience. That's years on the internet by the way. I come here to give for free my experience and all I get is bs from people who are experts in their own dreams. Sad...Too bad. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted August 20, 2013 Share Posted August 20, 2013 I have only been at this for about 20 years. mostly hobby level, but I have worked in a grey iron foundry, and cast a bit myself here, and I see you telling us something does not work, when I have in fact seen it work, now you insult us, even stating that Frosty is full of it. I am also aware that some large things do not scale down and work the same way in the home shop, meaning some things have to be changed for small crucibles from how they are done in large melts. I can see this is getting out of hand. Everyone needs to try to get back in focus, until then I am locking this thread for a few days to let people cool off Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted August 24, 2013 Share Posted August 24, 2013 now that we have had some time to re think the issues here, I hope we can continue the discussion without our passions getting in the way of brotherhood. The thread is re-opened, unless it goes south again. Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted August 24, 2013 Share Posted August 24, 2013 We are nothing if not passionate. Quote Link to comment Share on other sites More sharing options...
Pete Buchanan Posted August 27, 2013 Share Posted August 27, 2013 joe has a valid point... hard refrac will hold up to real use (everyday use) while blanket will work it wont last like the hard will.... so if your a hobbist like 90% of the folks on here, blanket will work for you Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.