Sand Pot, could it be a salt replacement.

[JZknives]

Much much less than pumping air directly around the steel

 

[JTknives]

Yes very true but still there.

 

[JTknives]

I just think that with proper diffusion this setup would us very little gas and should not be looked at as a drawback but a very universal shop tool that can be used for everything from forging to heat treating. But also remember you don't always have to use argon, you can use air for just getting it heated then switch to argon to do the actually heat treating. Or use any other gas you want that might be cheaper.

 

[JTknives]

Double post

 

[JZknives]

I was merely asking that the machine could be made less complex to operate with alternative ways to mix the sand.

It would also potentially create less scale

 

[Rody]

Usually vibration is used to compact sand so I would think the effect would be the opposite of what you want...

 

[KnuckleDownKnives]

Usually vibration is used to compact sand so I would think the effect would be the opposite of what you want...

+1.

I would think it would tend to compact than separate. Most machines that use vibratory systems tend to keep a medium moving in a certain direction through the system vs fluidizing it in a containment. Of course you have your vibratory tumblers and such, but introducing the amount of vibration it would take to make the sand act in a fluid state would be very dangerous I would think, and the idea behind this is to take away the dangers present from using salt. Using vibration with sand vs a salt pot would be trading one danger for another. IMHO.

 

[JTknives]

And the vibration tumblers only work because of the shape of the bowl. This shap causes the sand/media to mix in a spining/rotating motion. I think it would be difacult to recreate this if the depth was incressed. There are bigger tumblers but the diamater also increases proportional to its depth.

 

[jdm61]

The idea of using air while getting the pot up to heat and then switching over to an intern gas may have some legs if you were certain that the air was "purged".

 

[Willie71]

My book has not showed up yet and I think I ordered it a few days befor you. Must take longer to ship to the middle of no where lol

One of you guys got my book. :grumpy: I got a refund as the book was no longer in stock. I haven't sourced it again, as there was some pretty great info in this thread and the articles linked.

 

[JTknives]

I think you should give it a few min on the "intern" gas to make sure it is indeed purged. Just the fact that the sand is mixing and going to the top will also carry the gas as well. but I think the duel system only makes sence if it uses a crap ton of gas. But there is also the possibility of using other gas that is much cheaper. Why could we not use propane as the fluidizing gas.

Before you go running around with your hands in the air yelling fire fire let's give it a thought. The gas would burn off at the top of the tube so there is that hazard but we deal with forges shooting flames out the doors so it's not something your not use to. The other thing is gas consumption but I don't think in the pot sizes we are talking about that it would be a problem. Next up would be does or would the super heated propane cause any negative effect on the steel befor it's burnt off at the top. By this I'm wondering if we would run into a carberizing problem. So I did some research and in prime carberizing environments it does not look like it would be much of a problem at the amount of time we would be soaking because carberizing is measured in hours not min. But here are a few graphs I found that show depth to time.

But let's leave that for now and move onto the next aspect of using propane. That is volume of total gas we have access to compared to price. The expansion ratio is 270:1 so one ft^3 liquid is 270 ft^3. But one cubic ft is 7.481 gal which means that for 270 cubic feet of has propane gas you need to buy 7.481 gal. So for me I pay $2.23 a gallon which is $16.68 for 270 cubic feet of gas. But look at the price of argon at an average of $50 per 100 ft^3. Now prices on compressed argon cane be wildly different between different suppliers even in the same city. But price also hugely depends on the amount you buy. But either way propane is much much cheaper.

On to the last point I think is worth pointing out. If propane would work for what we need then we only need one gas, one bottle and one regulator. This is huge for me because I can haul my 50lb propane tank to the gas station in my car for a fill. Also less shop space taken up as well as I already own the bottle. You would set the pressure on the regulator to the pressure needed for your burner and then set the flowing pressure for the sand with a needle valve. This would make things much more simple in design and setup.

With this all being said something popped into my head which I don't know if it would be an issue or not. That would be carberizing of the sand pot but I don't know if you can carberize stainless.

Here is the carberizing charts

 

[jdm61]

LOL. Stupid spell check can't tell INERT from Intern.

I think you should give it a few min on the "intern" gas to make sure it is indeed purged. Just the fact that the sand is mixing and going to the top will also carry the gas as well. but I think the duel system only makes sence if it uses a crap ton of gas. But there is also the possibility of using other gas that is much cheaper. Why could we not use propane as the fluidizing gas.

Before you go running around with your hands in the air yelling fire fire let's give it a thought. The gas would burn off at the top of the tube so there is that hazard but we deal with forges shooting flames out the doors so it's not something your not use to. The other thing is gas consumption but I don't think in the pot sizes we are talking about that it would be a problem. Next up would be does or would the super heated propane cause any negative effect on the steel befor it's burnt off at the top. By this I'm wondering if we would run into a carberizing problem. So I did some research and in prime carberizing environments it does not look like it would be much of a problem at the amount of time we would be soaking because carberizing is measured in hours not min. But here are a few graphs I found that show depth to time.

But let's leave that for now and move onto the next aspect of using propane. That is volume of total gas we have access to compared to price. The expansion ratio is 270:1 so one ft^3 liquid is 270 ft^3. But one cubic ft is 7.481 gal which means that for 270 cubic feet of has propane gas you need to buy 7.481 gal. So for me I pay $2.23 a gallon which is $16.68 for 270 cubic feet of gas. But look at the price of argon at an average of $50 per 100 ft^3. Now prices on compressed argon cane be wildly different between different suppliers even in the same city. But price also hugely depends on the amount you buy. But either way propane is much much cheaper.

On to the last point I think is worth pointing out. If propane would work for what we need then we only need one gas, one bottle and one regulator. This is huge for me because I can haul my 50lb propane tank to the gas station in my car for a fill. Also less shop space taken up as well as I already own the bottle. You would set the pressure on the regulator to the pressure needed for your burner and then set the flowing pressure for the sand with a needle valve. This would make things much more simple in design and setup.

With this all being said something popped into my head which I don't know if it would be an issue or not. That would be carberizing of the sand pot but I don't know if you can carberize stainless.

Here is the carberizing charts

 

[Drew Riley]

Would there be a big enough disadvantage of using something like Nitrogen instead of Argon? If I'm not mistaken, Nitrogen is quite a bit cheaper than Argon, is it not? Is it cheaper than propane?

 

[Rody]

Or CO2...doesn't get much cheaper AFAIK

 

[Fiddleback]

I'm going to try to set one of these up. We have an old ceramics kiln from craigslist. I'm going to mod the top and use a larger diameter tube as my sandpot. This was an exciting thread JT. Thanks.

 

[Stacy E. Apelt - Bladesmith]

Some thoughts and ramblings:

A sand pot tube will be far easier and safer than a salt pot tube to build at home, as it isn't containing a liquid and there is no serious risk if a weld has a leak.

A fluidized bed sand pot can be built and experimented with as a tube alone. This will allow changes in air/gas injection and quick modifications to be done at room temperature. Once the fluidizing action is sufficient and all the design issues are tackled, then build it into a kiln or forge. The tube and air/gas setup can be done for probably less than $100.

I sketched a 12" per side hexagonal fire brick arrangement that would be easy to build and reasonably priced. I will have to compare that with the extra difficulty and time to build it from wool and satanite.
A simple cutting jig made from 2X6" wood would allow cutting all the bricks for a perfect fit. By stacking the bricks flat, you have 4.5" of refractory wall thickness. 9 bricks per layer and 3" height per layer would make a 30" tall forge (for a 24" deep sand tube) about $500 in bricks ( roughly 100 bricks).

I am also considering a build with two layers of 1" ins-board as the chamber walls. Both scenarios allow for placement of burners and such to be made after the chamber is assembled, and for easy changes with just a little patching up.

Now, I have about 2000 pounds of castolite-30 castable refractory sitting in a storage unit. There is a wild part of me that says this great excess has been waiting for a massive HT chamber to be cast. I'll have to think about it, but there would be no cost for the major component that way. I could build it as large as I want, and would only have to wrap it in an inch of wool and a sheet metal jacket. Heck, I could probably jacket it with a couple inches of kitty litter and get no heat loss at all. I would have to build it in place on a rolling base, as it would be very heavy.

 

[Natlek]

Some thoughts and ramblings:

A sand pot tube will be far easier and safer than a salt pot tube to build at home, as it isn't containing a liquid and there is no serious risk if a weld has a leak.

A fluidized bed sand pot can be built and experimented with as a tube alone. This will allow changes in air/gas injection and quick modifications to be done at room temperature. Once the fluidizing action is sufficient and all the design issues are tackled, then build it into a kiln or forge. The tube and air/gas setup can be done for probably less than $100.

I sketched a 12" per side hexagonal fire brick arrangement that would be easy to build and reasonably priced. I will have to compare that with the extra difficulty and time to build it from wool and satanite.
A simple cutting jig made from 2X6" wood would allow cutting all the bricks for a perfect fit. By stacking the bricks flat, you have 4.5" of refractory wall thickness. 9 bricks per layer and 3" height per layer would make a 30" tall forge (for a 24" deep sand tube) about $500 in bricks ( roughly 100 bricks).

I am also considering a build with two layers of 1" ins-board as the chamber walls. Both scenarios allow for placement of burners and such to be made after the chamber is assembled, and for easy changes with just a little patching up.

Now, I have about 2000 pounds of castolite-30 castable refractory sitting in a storage unit. There is a wild part of me that says this great excess has been waiting for a massive HT chamber to be cast. I'll have to think about it, but there would be no cost for the major component that way. I could build it as large as I want, and would only have to wrap it in an inch of wool and a sheet metal jacket. Heck, I could probably jacket it with a couple inches of kitty litter and get no heat loss at all. I would have to build it in place on a rolling base, as it would be very heavy.

I did not really understand what you exactly mean without drawing , but what do you think about this? I need to drill a few more bricks to get about 18 inches in height, the hole is 4 inches now ...... 2.5 inch stainless steel tube would be enough for small knive ?

 

[Brian Ayres]

http://www.mantectechnicalceramics....ramics/fluidisation-and-aeration/fluidisation

At the bottom of this page. The applications specifically says Fluidised Burners. Basically it says to sandwich a flat brick in the bottom of the burner and cement around the sides.
I deal with this type of material in burners on water heaters. I have worked on up to 2,000,000BTU burners for boilers so I am not unfamiliar with burner technology.


One other thing. Let's not all forget that while not salt dangerous, a shotgun blast of over pressurized sand started this thread. Lol. A 2.5" sand pot is a 1600 degree shotgun blast to the face waiting to happen. The velocity increase of the air flow through the small tube could potentially be extreme.
A properly sized and set pressure regulator should be installed to prevent accidental over pressurization. Possibly another reason propane might be a good fluidizer. I hope this works out as I truly need to put together a good heat treat setup and this would also allow forging Damascus especially fluxless welding methinks from the same forge/burner bed.

 

[Brian Ayres]

http://www.motherearthnews.com/renewable-energy/fluidized-bed-combustion-zmaz80sozraw.aspx

And this is something to think about. Building a fluidized bed burner for you coal/off the grid guys and people with kids named Fire, there is a possibility of making a coal fired combustible burning burner.

 

[Salem Straub]

Building a fluidized bed burner for you coal/off the grid guys and people with kids named Fire, there is a possibility of making a coal fired combustible burning burner.

Hey, I resemble that remark!