Ruddock Posted June 17, 2015 Share Posted June 17, 2015 I'm making a propane forge which needs a 8 or 9 inch chamber. The problem is the amount of insulation needed. I've done a bit of research and noticed that most people used a layer of ceramic blanket about an inch thick, a layer of castable refractory and itc 100, my question is how many layers of ceramic blanket and how much castable refractory is necessary to sustain heat, the forge will be a blown propane forge. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 17, 2015 Share Posted June 17, 2015 Do you plan to weld in it? Is propane cheaper than refractories where you are at? How do you plan to use it? Long periods at high heat with large items, short runs with small stuff? etc... Quote Link to comment Share on other sites More sharing options...
Ruddock Posted June 17, 2015 Author Share Posted June 17, 2015 Plan to use it for forge welding knife billits, but high temps are needed and so what amount of insulation can aid this process. I know that flux degrades the blanket which is why the refractory cement is needed but would 1 1 inch blanket be sufficient Quote Link to comment Share on other sites More sharing options...
WayneCoeArtistBlacksmith Posted June 18, 2015 Share Posted June 18, 2015 Check out the two tutorials on my Forge supplies page on my web-site. I suggest that you build the forge according to the "Build a Gas Forge" attachment and build a Ribbon Burner for it. The Build a Gas Forge attachment was written before I had built a Ribbon Burner forge but will work just as well with a Ribbon Burner. I am welding billets in my forge with out flux and therefore no inclusions. Let me know if I can help you. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 18, 2015 Share Posted June 18, 2015 How much are you willing to spend on propane? More insulation = less propane. I'd rather spend an extra US$20 on insulation if it would save me $200 in propane over the life of the forge---I'm cheap that way!I once had left my forge go way too long without relining, I kept turning up the regulator to keep the heat up. Well I finally relined putting the new layer over the old layer and forgot to turn the regulator down and the first time I used it my piece *MELTED* Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted June 18, 2015 Share Posted June 18, 2015 Most folks I have seen go for 2" of insulation. And step up a size on the shell, unless your using a monster press or powerhammer somthing on the order of 8-9" deap is sufficent. Quote Link to comment Share on other sites More sharing options...
Ruddock Posted June 18, 2015 Author Share Posted June 18, 2015 Thanks Charles, think I'll use 1 layer of ceramic blank and an inch of refractory cement and a wee coat of itc-100. I think this should be sufficient. Quote Link to comment Share on other sites More sharing options...
LastRonin Posted June 19, 2015 Share Posted June 19, 2015 Refractory cement absorbs heat. You'll have to wait longer for it to get to heat, and I believe use more fuel. More blanket and less refractory would be more efficient I believe. Quote Link to comment Share on other sites More sharing options...
WayneCoeArtistBlacksmith Posted June 19, 2015 Share Posted June 19, 2015 Refractory cement absorbs heat. You'll have to wait longer for it to get to heat, and I believe use more fuel. More blanket and less refractory would be more efficient I believe.Except that Kast-0-Lite is a light weight, insulating castable refractory and it forms a hard surface so that every time you touch it with a piece of metal you don't poke a hole in it. The Plistix or Metrikote will reflect the IR back into the forge. I use the Plistix or Metrikote as a skim coat over the casting.If you don't want to cast the interior you can just paint over the blanket with the Plistix or Metrikote to contain the floating fibers and to reflect the IR, just expect to be doing frequent repairs.Let me know if I can help you. Quote Link to comment Share on other sites More sharing options...
Dodge Posted June 19, 2015 Share Posted June 19, 2015 Many people have built many forges over the 15 or so years since I started smithing and I'm sure many more before that. The majority have found that a liner of 2" of ceramic wool seems to be the magic number. Any less and you lose too much heat through the forge wall. You can almost lay a bare hand (I did say almost ) on the outside shell of my forges while running. This should indicate that there is not a great deal of heat loss through the 2" of blanket and thin layer of refractory mortar I use as a rigidizer. Of course, if it was cold to the touch, it would mean little to none. As a contrast, I know of a shop that built their forges from a 2" wall of castable refractory with an inch or so ceramic blanket on the outside. They ran them off natural gas and ran them for 8 - 10 hours a day so weren't too concerned about the fairly long heat up time first thing in the am, compared to the short time of a ceramic liner on the inside. That being said, even at the later part of the day, one could lay a bare hand on the top of these forges (Used for welding 3/4" and larger steel) and would find the temperature less than warm...Scott Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 19, 2015 Share Posted June 19, 2015 Didn't you start out wanting to build a 2' long forge to make swords? Have you read the gas forge section? Your questions have been answered so many times already I'm pleasantly surprised how patient the guys replying to you again are.Wayne has very complete instructions with materials list and supplies for the reading. I get the impression you either don't know how to calculate volume or just want someone else to do it for you. Either has a simple solution math for dummies is really cheap at used book stores and may be available online. I have a lot of the "For Dummies" books.If you want someone to do it for you get out your wallet and place an order.I've resisted replying as I'm starting to lose patience with folk who won't do even basic research. How do you expect to do something that requires specific and detailed knowledge coupled with a lot of experience if you won't read a few hours worth of available forge building information? If you don't understand all those posts I don't see how you expect to understand what we might tell you now.Really, the best bladesmith on earth CAN NOT teach you a thing. The best any of us can do is offer information, it's up to YOU to learn. Insisting on answers that meet your expectations is too unrealistic to succeed.Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted June 23, 2015 Share Posted June 23, 2015 Didn't you start out wanting to build a 2' long forge to make swords? Have you read the gas forge section? Your questions have been answered so many times already I'm pleasantly surprised how patient the guys replying to you again are.Wayne has very complete instructions with materials list and supplies for the reading. I get the impression you either don't know how to calculate volume or just want someone else to do it for you. Either has a simple solution math for dummies is really cheap at used book stores and may be available online. I have a lot of the "For Dummies" books.If you want someone to do it for you get out your wallet and place an order.I've resisted replying as I'm starting to lose patience with folk who won't do even basic research. How do you expect to do something that requires specific and detailed knowledge coupled with a lot of experience if you won't read a few hours worth of available forge building information? If you don't understand all those posts I don't see how you expect to understand what we might tell you now.Really, the best bladesmith on earth CAN NOT teach you a thing. The best any of us can do is offer information, it's up to YOU to learn. Insisting on answers that meet your expectations is too unrealistic to succeed.Frosty The Lucky.Second that emotion. However, two inches of blanket is a good start. My current preferred build is two inches blanket surrounding dry laid insulating brick that is coated with High temperature reflective refractory. One master blade smith I knew had one furnace for billet work and a second for all other work. Quote Link to comment Share on other sites More sharing options...
Stormwalker Posted September 24, 2015 Share Posted September 24, 2015 I know this late to the discussion, but Frosty and Charlotte, thank you for weighing in on the amount of insulation, and the information about how each performs. This was EXTREMELY helpful. I also think is great that you "cough cough" encourage people to work things out for themselves, rather than spoon feeding them. I think it makes for a better knowledge of the "machine" (in this case - forge ) as well as a better understanding of WHY things are the way they are, rather than just shrugging and not digging deeper.Storm Quote Link to comment Share on other sites More sharing options...
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