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I Forge Iron

can I modify this or just start new?


BHein

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I have a paintcan forge I built for heat treating knives. I have had very mediocre success with getting it hot enough. I started with a bernzomatic torch and propane, upgraded to mapp gas and went to an oxy/map gas setup. The oxy/mapp gas set up has reached adequate heat treat temps, but I am going broke buying small cylinders to keep it operating (one 1.4oz oxy tank will heat treat two knives). I want to install one of frosty's T-burners in this but, I am considering building a whole new forge so I can get to welding heats to eventually start doing some Damascus work.

To make a long story even longer, I am working in a small shop (12'x24') so size is a factor. I have very quickly come to appreciate the vast amount of experience and wisdom contained on this forum so before I start to construct another forge I would see if this one could work. 

IMG_0282.JPG

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No it's not the simplest or  cheapest; you have already spent several times the cost of a kaowool liner trying to get it up to heat not to mention all the different burners/fuels you have already worked with.  Stop throwing good money after bad. Trashcan that liner *NOW*; put in 2 inches of kaowool and get to forging!

 

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  • 2 weeks later...
On 11/1/2015, 11:43:38, BHein said:

I have a paintcan forge I built for heat treating knives. I have had very mediocre success with getting it hot enough. I started with a bernzomatic torch and propane, upgraded to mapp gas and went to an oxy/map gas setup. The oxy/mapp gas set up has reached adequate heat treat temps, but I am going broke buying small cylinders to keep it operating (one 1.4oz oxy tank will heat treat two knives). I want to install one of frosty's T-burners in this but, I am considering building a whole new forge so I can get to welding heats to eventually start doing some Damascus work.

To make a long story even longer, I am working in a small shop (12'x24') so size is a factor. I have very quickly come to appreciate the vast amount of experience and wisdom contained on this forum so before I start to construct another forge I would see if this one could work. 

IMG_0282.JPG

There are so many questions you haven't asked, which you really need to. I would suggest that you look up Larry Zoeller Forge as the most practical starting point for free information on building small forges. Either a Frosty "T" burner or Larry's modified side-arm burner would do fine in such a forge. Build the forge properly and forget about so called MAPP gas (which is actually propylene as MAPP has not been manufactured since 2008). If you must use propylene it is much cheaper purchased in regular industrial cylinders from a welding supplies store, but if you build your burner and forge correctly propylene gas and air would be much too hot to run in it, let alone propylene and oxygen. You can also input "Mikey Burner" to learn a lot more than you know on the subject of constructing burners.

The only comprehensive source of information on the subject is still my book (Gas Burners for Forges, Furnaces, and Kilns); do you have to buy it? Nope; it has been pirated so much that there are about 120 sites advertising free PDF downloads on any given day. Of course, there is an old saying about laying down with dogs and getting up with fleas...have fun, and watch your six.

Michael Porter

There are so many questions you haven't asked, which you really need to. I would suggest that you look up Larry Zoeller Forge as the most practical starting point for free information on building small forges. Either a Frosty "T" burner or Larry's modified side-arm burner would do fine in such a forge. Build the forge properly and forget about so called MAPP gas (which is actually propylene as MAPP has not been manufactured since 2008). If you must use propylene it is much cheaper purchased in regular industrial cylinders from a welding supplies store, but if you build your burner and forge correctly propylene gas and air would be much too hot to run in it, let alone propylene and oxygen. You can also input "Mikey Burner" to learn a lot more than you know on the subject of constructing burners.

The only comprehensive source of information on the subject is still my book (Gas Burners for Forges, Furnaces, and Kilns); do you have to buy it? Nope; it has been pirated so much that there are about 120 sites advertising free PDF downloads on any given day. Of course, there is an old saying about laying down with dogs and getting up with fleas...have fun, and watch your six.

Michael Porter

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On November 1, 2015 at 8:35:57 PM, BHein said:

It is plaster of paris and sand. It was the simplest/cheapest starting point, I definitely want to upgrade to kaowool in my next one tho.

As Thomas mentioned, you're really screwing yourself over with that kind of junk in the forge.  Some imbecile puts a video on youtube and next thing you know, everyone wants to believe sand and plaster makes a decent insulation instead of actually thinking things through for a minute.

If sand and plaster was good stuff, you'd see every professional out there using it.  If it was cheaper and did the same job as Kaowool, nobody would be buying kaowool.  There'd be no talk of kaowool, Satanite, refractory cement, plistix, etc.  All of the kiln and oven manufacturers would be using sand and plaster in the products they sell rather than the "more expensive" stuff they're currently using.

Then you cancel your savings on the insulation by buying can after can of fuel, trying to get a decent heat.  Why?  Because the insulation isn't insulating. It's just a heat sink.

Get with Wayne for some proper supplies and build a proper forge.  You'll be very happy that you did.

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As I mentioned in another post on this forum the same thickness of high temperature glass fiber blanket is around 10 times better insulating material than a plaster/sand mix from what I could find regarding these materials.  Even though there are certainly some losses due to radiation out the open door and convection of the heated combustion byproduct gasses, this is a rather significant difference.  This is not even taking into account the thermal mass of the plaster/sand mix which will take a lot of time to heat up every time you fire the forge up.

As Vaughn correctly states, using this material for a gas forge liner is a false economy, unless you get free fuel...

I'm in process of building a quick paint can forge to use as a demo for my blacksmithing group this weekend.  I plan to use a scaled down Frosty T burner (1/2" dia. burner tube with a 0.23 MIG tip).  This forge will be insulated with Kaowool and will have both front and back door openings.  If successful I will post results, but I fully expect it to get up to forging temperatures easily.

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  • 3 weeks later...

Wayne's website is a good one. I have built many casting furnaces using Kaolite 3000, and find it to be hard wearing, and and quick to heat up; it also requires no kiln shelf, as it's already resistant to flux, and will support work pieces just fine. So what's the difference between this kind of construction and straight ceramic fiber? About ten minutes more heating time, if you finish coat it with a high-emissive coating, and if you use a secondary layer of fiber insulation, so that the inner layer of cast refractory isn't thicker than an inch. Such construction can provide a full time working shop with the best blend of heartiness and efficiency in a heating tool.

I also agree with his hinged design, something I've pondered doing for years, but never got around to trying; I'm glad Wayne did.
The article posted on his site about ribbon burners and how to build them is the best information I've found on the Net thus far.

And, I don't think you can find a more reasonable source for purchasing the small amounts of refractory products anyone building a knife forge uses.

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Apologies to BHein for hijacking this thread.   Can anyone expound on the nuances of Mizzou 3000 vs Kastolite 3000?  I've heard that Mizzou is more durable and that Kastolite is more insulating.  Also, according to Wayne's website on the ribbon burner pdf, Mizzou can be used for this type of burner.  Would Mizzou be a more universal type of castable refractory between naturally aspirated forge interiors and that of ribbon burners?

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Mizzou is a high density, high temperature castable with fair resistance to molten glass (flux).  Refractory castables with higher percentages of alumina and/or zirconia have better flux resistance. It has very little insulating value (close to that of concrete).  As you noted, it is a good choice for forge liners, if you are looking for a high thermal mass forge (and plan on backing it with some kind of high temperature insulating material), and ribbon burners.  It is more economical than the equivalent high alumina refractory castables and in my experience a bit less prone to thermal shock.  It also has a coarser surface finish than the high alumina castables, which can be an issue with ribbon burner ports.  Additional info here: http://supplies.foundryservice.com/item/castable-refractories/dense-castables/mizzou

Kastolite 3000 is a castable insulation which can be used for a forge liner as well without  specific requirement for backing insulation. It is still higher mass and less insulating value than refractory blanket insulation, so you will need more thickness to get an equivalent insulating lining.  As far as I know, Kastolite is not very resistant to flux, so some kind of inner protection, at least at the forge base, may be required.  A composite lining of an inner wall of 2-3" Kastolite wrapped with an inch of blanket, and a forge floor of bubble alumina, Mizzou, or Greencast 97 might be the best of both worlds, though it will certainly heat more slowly than a blanket insulated forge with a thin refractory liner.  Additional info here:  http://supplies.foundryservice.com/item/castable-refractories/insulating-castables/kaolite-3000-kast-olite-30-li

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