Sand Pot, could it be a salt replacement.

It was fun seeing that sand "boil" when you put the hot blade in it, but what was even more interesting was how much more even the heating of the blade appeared just by eyeball test when you used the high temp sand pot compared to the forge. You looked a tad overheated at the tip coming out of the forge, but not so with the sand pot.
 
You can get very fine hole, but thick stainless mesh "screen" material from McMaster, I've got some on hand I was planning to try stacked in layers for the diffuser.


I'm gonna order some media, 120 grit AO with the best grading consistency is what we want right? Anybody find a good source?


Is there any reason not to use Argon for this? (I haven't read half the links posted, sorry, been busy getting ready for a show), seems like the expansion under heat would require only a very small flow rate from what's being described.

I've got a complete setup ready to test this, just need media and to throw together a burner.
 
javand said:
You can get very fine hole, but thick stainless mesh "screen" material from McMaster, I've got some on hand I was planning to try stacked in layers for the diffuser.


I'm gonna order some media, 120 grit AO with the best grading consistency is what we want right? Anybody find a good source?


Is there any reason not to use Argon for this? (I haven't read half the links posted, sorry, been busy getting ready for a show), seems like the expansion under heat would require only a very small flow rate from what's being described.

I've got a complete setup ready to test this, just need media and to throw together a burner.
Click to expand...

I have a full tank of Argon, so I will be using it in my setup when I make it.
 
Read in one of the articles that the diffuser can be made by using course media at the bottom of the bed. The course media is not fluidised but contributes to distribution of the air. Possibly a pipe into some course sand for the diffuser?
 
JT thanks for documenting your journey for us to follow along. I enjoy reading all the posts and ideas and I like seeing everyone work together to help make this a success. Having a salt pot on my list of future upgrades I think I will modify that to sand providing all this works out.

For the diffuser I was thinking that small holes in the stainless brake line then shape a soft fire brick to the size of the bottom of the main tube. Drill into the side of it so you can insert the brake tube into it and use it the same way you would a air stone for a fish tank. I would weld the end of the break tube closed so the pressure out of the holes would be constant and help disperse the air/gas better through the fire brick. I'm thinking that drilling in the top, bottom and sides of the tube would help disperse air through the brick better. This may not be as effective as the mesh Javan mentioned so long as that keeps the fine sand out.

Looking forward to more!

-Clint
 
I don't see any reason not to use argon. I'm really supersize at how little is needed. Also even with how little I use I would say 50% is going back out the hole where the pipe enters the bottom of the tube.

Now that I have played with it more I think my first eruption was the fault of the media used. That being said if using aluminum oxide I bet you don't need to flow the gas till your ready but I would flow the gas a little while befor just to make sure the temp is evened out.

Using corse media in the bottom might work perfect for what we need but I think we need something that's heavier then the sand so it does not float. But if you where to fill the bottom 1" or so with stainless ball bearings that might just be the ticket.

As to the even heating of the sand I was shocked. It was a HUGE difference compared to just sitting verticle in the forge. If you look at the long bar I pull out first it's very even. To my eye that bar looked the same color on both ends I was shocked. Can only get better with the proper sand.

The great thing about this is you can convert a salt pot to this very quickly and easily without permanently modifying it. What would be the cherry on top is a wide flared end that catches the sand and funnels it back into the tube.
 
I don't know if soft firebricks is as porous as aquarium stone. What about seeing if the stuff used for aquariums will flow enough gas and if it is available in a large enough size?
 
If the sand works well enough for our purposes, then the danger of he salt makes using LESS attractive unless you are using steels that can REALLY benefit from it compared to sand, possibly HSS. I was told by the MetSol guys in Providence that precise heat treating of HSS is pretty much what keeps the in salt pot business.
JTknives said:
I don't see any reason not to use argon. I'm really supersize at how little is needed. Also even with how little I use I would say 50% is going back out the hole where the pipe enters the bottom of the tube.

Now that I have played with it more I think my first eruption was the fault of the media used. That being said if using aluminum oxide I bet you don't need to flow the gas till your ready but I would flow the gas a little while befor just to make sure the temp is evened out.

Using corse media in the bottom might work perfect for what we need but I think we need something that's heavier then the sand so it does not float. But if you where to fill the bottom 1" or so with stainless ball bearings that might just be the ticket.

As to the even heating of the sand I was shocked. It was a HUGE difference compared to just sitting verticle in the forge. If you look at the long bar I pull out first it's very even. To my eye that bar looked the same color on both ends I was shocked. Can only get better with the proper sand.

The great thing about this is you can convert a salt pot to this very quickly and easily without permanently modifying it. What would be the cherry on top is a wide flared end that catches the sand and funnels it back into the tube.
Click to expand...
 
what I would like to research personally would be how to make air holes small enough in the tubing that the media can't get into them. There has to be some sort of process that can achieve this whether it be chemical, electrical or mechanical.
 
Yeah, even tiny wire drills will be larger than 120 particles. I like the coarse media on bottom idea. I have argon on hand anyway for the TIG, so if it does not use much, that'll work out well. Might try JT's valving idea- come up to heat with air, then switch to argon before inserting blades.

JT, here is the link to that book by the way. Lots of good stuff there.
https://books.google.com/books?id=A...fluidized bed heat treating equipment&f=false

ETA: I watched the quench video... that was cool. It looked to have cooled it quite a bit, quickly. I was reading that it could quench comparably to slower oils... but imagine, quenching into argon fluidized sand, no nasty oil to clean off... or as mentioned above, maybe following with a superchilled fluidized bed!
 
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Joe the only issue I see with actual aquarium stone is that I don't know how it reacts to high temperatures. I think a porous stone like that would be ideal but I would be afraid of it exploding. Perhaps some tests are in order.

I like the ball bearing idea but do you guys think that the sand would eventually fill up the negative space in between the bearings and eventually make its way into the tube?

-Clint
 
You could cut slits in the tubing with a wire edm but even that has its limits. When I ran a wire edm normal wire we used was .010 thick but .004-.005 could be used but was a pain in the butt. But the wire will over burn making a .010 wide slot .012 wide. Also very expensive to have stuff made with one. About $150hr at a machine shop. When I was in the silencer design and manufacture business I was doing heavy research into using ceramic foam. It's an open cell foam like any other but can be made from almost any material including ceramic and silicon carbide. You order it using 2 factors density and ppi (pores per inch). I have been looking into it again for this project but the only hitch is that it's expensive and only a few places make it. This technology is also used in making filters for filtering liquid metal befor casting. And these filters can be bought but the PPI is usually much smaller and the density is much less as well. What we want is a very high PPI and also high bulk density. Bulk density is how much of that square inch is silicon carbide. So having a low bulk density and low PPI means you have few holes per inch and thy are large. If you had a low PPI and a very high bulk density then you have few holes per inch and thy are small. So it's a trade off because higher density means more strength but less holes. But it can only be cut with a wire edm.
 
Augus7us said:
Joe the only issue I see with actual aquarium stone is that I don't know how it reacts to high temperatures. I think a porous stone like that would be ideal but I would be afraid of it exploding. Perhaps some tests are in order.

I like the ball bearing idea but do you guys think that the sand would eventually fill up the negative space in between the bearings and eventually make its way into the tube?

-Clint
Click to expand...

This stuff flows like water when peserized so once you cut the air it's flowing where ever it can get to. But I think what we are after is breaking up any large bubbles so thy don't cause large boiling action.

The only thing I can see with using screen is to block the sand it will need to be very fine mesh. And even stainless will scale off at thoes temps so I'm wondering how long the screen would last.
 
Maybe kitty litter of some type, many people use it in the bottom of their forges for a flux barrier.
 
You know that if you could devise a "plug and play" version of this using a basic 12-16 vertical blown forge design, it could probably be had at half the price of a high temp salt setup and you could get your gasses at any local welding shop, right? PLUS you would have a welding capable forge to boot. Maybe a setup with a hinged bottom for easy cleanup and swap out and a hollow steel "plug" for the top hole filled with castable refractory material? That is another $400-500 saved. That doesn't even take into account that you might not even have to buy a dedicated HT oven for tempering. ;) Just out of curiosity, how much space do you have between the outside of the sand pipe and the walls of the forge? I know that Ed Caffrey and others have built oblong forges buy cutting well casing pipe and welding in flat sides in oder to get deeper welding forges. i am wondering how big you would have to make the forge and the pipe in order to say heat treat wide pieces like integral tactical tomahawks? What kind of pipe do you have to use of the actual "pot?" You obviously do not have the corrosion issues that you do with salt.
 
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Another fun question. Could this be the fluidized setup that you could use to heat treat a clayed up blade with worrying about blowing your entire shop up with you in it? ;)
 
From what I understand, a fluid bed quench will not reach the speed of fast oil or water or even salt, so hamons might be a no go entirely.
That said, using the more expensive shielding gases like helium and hydrogen expedite heat transfer, much above the qualities afforded by fluidizing with plain air or even argon. That, and the fact that the sand can be run at a lower temp than salt and that the cross sections being quenched are quite thin metallurgically speaking, leads me to think that it's not necessarily out of the question.

An interesting thing about fluid bed quenching is that the quench speed can be customized by tweaking the fluidizing gas, particle size, gas flow, and temperature of the pot.

Javan, I like the kitty litter idea! I have some cheapo clay litter in my shop, just for the welding forge floor. Might work!
 
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