Sand Pot, could it be a salt replacement.

Here it is with the tweaking.
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I put the indexing tabs on the underside of the plate. Makes things cleaner looking.
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Ah great! So now you have a sandtube-collector combination, that is probably the most handy? Cause, you could also make one longer tube, and lower the plate in this tube, than there would be only one tube, but that might have some other cons..? Alu-oxide getting in places where you don't want it upon demount of the oven? Just writing down my thoughts here...
 
If you do hat the sand will get between the cover plate and the tube. That's a problem I have right now. If the fit was tight enough then it would reduce that but then it would make it much harder to make and a good chance it would get stuck. Also you want that plate sitting on something so the forge body is taking the weight not the insulation liner.
 
JTknives said:
Ok I did a little testing and have mixed results. The testing befor heating went amazing, nice and fluid at a low flow rate. Then I started heating and holly crap this aluminum oxide was releasing some noxious fumes. About choked me out when I went to look inside the pot. Had to step out of the shop till it was burned off what ever it was. It was not pleasant at all, but after it got up to temp it was all gone and ok. So let that be a warning to you guys. I don't know what could be burning but I'm guessing it's some impurities from manufacturing. When I got choked out I shut off the air to the sand and stepped out side. This was a mistake I think because the sand kinda clumped up in the bottom and messed up my fludizing effect. Also the grains look clumped together. I had a wad of kowool in the bottom and the sand clumped onto it because the air was not flowing. So I am letting it cool down and I'm going to start over and keep it circulating the entire time it burns off. I could tell I had a problem because when it was at temp it was not mixing and it was chugging bad when I would turn it up to increase the flow. This told me one of 2 things. 1- I have a plugged bottom and air is forming a large bubble or 2- the heavier sand needs a larger diamater pot to reduce the chugging. The air was flowing along and up the side of the pot. So I'm guessing there was a hole in the clump at the bottom at the side of the pipe. So once it's cold I will reset and start over.
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Is it possible that they sale to you crushed sand from old worn grinding stone ? And that noxious fumes come from binder used in process of making grinding stone ? I used this way to get sand for sand blasting ............
 
FWIW, I figured I'd post this here as it's obviously relevant as well as it being Peter's HT. Not sure if you guys have seen this or if it will be of any help to ya since you have the books and have already spoken with the guys at Peter's over the phone, but I figure what the heck! :D

If you don't want to watch the full vid, go ahead and skip to 6:10 which is where they are showing their salt pot running.

Looks like they put their (carbon steel) knives in a caged basket and have them hanging in there vertically, then when everything's reading to be quenched they lift the whole basket out of the "sand pot" and lower the entire thing into the quench tank. Also, I heard Brad say the gas being used to fluidize the sand is Nitrogen. Forgive me if that's already been covered, but I thought I read a comment here with somebody asking why not use Nitrogen instead of Argon, as it may be cheaper, or something like that. Anyway here ya are.

[video=youtube;OvC4M_JrJlw]https://www.youtube.com/watch?v=OvC4M_JrJlw[/video]

~Paul
My YT Channel Lsubslimed
... (It's been a few years since my last upload)
 
Nitrogen is what is commonly used. I think argon was brought up because lots of guys already have argon tanks for there welders.
 
Ah, great vid! Thanks! Wow, this toolsteel analyzing gun is crazy! What an awesome piece of equipment.
 
I found locally pure aluminum oxide and SIC and for free .......what I read here is that grain size 100 /which a 0.13mm average size / is ideal for this .But before I start to make sand pot I need to know something .JTkinves , in your setup how much time it take to get say 1500 F ? I don t HT many knives at once , most one and that in a month...so I need to know what is the cost ...Thanks in advance :thumbup:
 
Natlek said:
I found locally pure aluminum oxide and SIC and for free .......what I read here is that grain size 100 /which a 0.13mm average size / is ideal for this .But before I start to make sand pot I need to know something .JTkinves , in your setup how much time it take to get say 1500 F ? I don t HT many knives at once , most one and that in a month...so I need to know what is the cost ...Thanks in advance :thumbup:
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In your situation, a sand pot would be a very poor choice in cost efficiency and time. A good HT oven would cost you far less.
 
I'm with Stacy on this one. Yes the salt pot heats up fast but besides the fact that its still in pre prototype stage I think it's not what you need. right now we are in design and testing phase and so it's not something I would build right now if I needed to heat treat. That being said you have to consider the costs in building and operating a sand pot or even an oven for that mater. By the time your done you will be $500-$1000 into it (rough guess). I was able to toss a test pot together for allmost nothing but I had everything already. And it was just to test the principle and function. It was never connected to a pid control to regulate temp. Now look at the number of knives you make. You said you don't heat treat often and do about a knife a month. With that it would take a long time to pay off a sand pot or oven. If it cost you $25 to send the blade out for heat treating then that's 20-40 months to pay off just the heat treat over or sand pot. This does not include the $150-$200 for a 5gal bucket of quench oil or a liquid nitrogen tank to cryo your blades. You get all thoes features on your blade when you send them out for $25 plus a vitrified hardness test. I do all my own heat treat in house, am I saving money, No but my time is valuable to me and when I have time to work on a blade I don't want to have to stop and send it out. My setup with my oven I build and liquid nitrogen dewar and quench tank filled with AAA quench oil and my aluminum quench plates has set me back over $2000-$2500 for everything. Not including the $70 to fill the dewar with LN.

So with all this being said I still think your best value is to send them out if your concerned about cost. I don't make knives to make money, I make knives because I LOVE it and love providing something for people that thy will have forever. But if your like me and love building stuff no mater the cost then have at it but a sand-pot is not what I would recommend if your just after heat treating. But if you want to join the cause and start prototyping and testing ideas to make the pot work better then your more then welcome to join the group.

Sorry if I sounded harsh, I was just trying to point out all the cold hard facts and give you solid advise.
 
Ok, I'll explain a little bit about me ... First and most important , I found that making knife relaxes me /not for sale / . Now, because of the nature of my business I have lots of contact which can be used to get different thing for free .I have many close friends who have different businesses .Say , one of them have workshop .......CNC , waterjet , industrial digital oven for HT ...liquid nitrogen ...many things that I can use for free. But I like to do it all myself .I'm surrounded by all sorts of industry ......steel , then composites factory where I can get various materials for the handles for free / waste material / but adequate size for handle .I have access for brick to make a house not oven and again for free. And so on....... I asked for time to heat and price, not because of cost but because I use small 10-liter bottle of LPG......I wonder whether it is enough for one cycle ....

But as you write , I love making tools too .... :thumbup:
If I start making electric oven , I must bye many things . And money is not so much the question .Problem is I do not have all that to buy in my country , must use internet or friends from foreign country and all that complicating things and I don t like that . That's way simple way to me is to make this sand pot .I have almost everything available here ........... 52100 , 1095 , 80crv2 , 15N20 ,5160 is steel I have and use and they have simple HT procedure .I have some 1.2519 steel but for that I use friends oven .....
Thanks for help !
 
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I have a little bit I can add to this, though it sounds like you're already finding better materials.
I used to operate a "sonic" drilling rig for soil sampling. It used variable vibratory frequency's to induce liquefaction as one of its methods for soil cutting and sample retrieval. It worked particularly well in sands if you could hit the right frequency. The drill string would basically fall through the sand under its own weight, much like a blade would in the HT pot you're trying to make. So theoretically I think it's totally possible to do this using linear oscillation (not random vibratory) but it would probably be bulky, loud, less efficient, hard to tune to the right frequency, and possibly dangerous when compared to the diffused air set ups. Not to mention massive cost to build an oscillator to power the thing. I could see the potential for a large industrial size vibratory tumbler unit being run, but it seems impractical for home use.
From that same work experience I also came in contact with small diameter stainless steel well screen. It sounds like the sintered diffusers or Kaowool boards or papers are probably a better choice, but there is precut stainless tubing available in small diameters with .010" slots. If you happen to know someone at an environmental drilling outfit they may have a scrap someone could put to use. But the cost is likely higher to buy well screen than to buy the better filter material. A layer of larger graded sand or aluminum oxide over the screen followed by the 120 grit would probably work for a while, but it would probably eventually start to intermingle over time forcing you to rebuild.
 
No update yet, but I am moving forward with a larger build soon. I think I got most of it figured out I just need to source all the components and put it togather. The biggest expense is the stainless tube and other then that most of the rest can be sourced local. Currently I have been using a small tube in my verticle forge and it works but the tube is to small. You need enough volume that when you insert a blade or bar it does not rase the level to much and over flow. I would like a 5-6" pot but we will see what I can find.

What I should do is just do a 15n20 sale as a fund raiser to get the funds rounded up to do the build. Problem is I'm also currently saving up for a Hardness tester so running a fund raiser for the sand pot would be the way to go. I don't want this project to fall into the cracks and be forgotten. I think it's a much better system then some currently available and much safer all things considered.
 
What size tube you want? I could roll it from this 10 gauge, or if thats too thin, I might have some obsolete seamless laying about.
 
4" to 6" is I think what we are shooting for. Out of 303, 304 or 316 stainless. I found all the stuff I need online but it's a good chunk of change to drop of an experamental prototype.
 
That's why I'm offering. I'm interested in building one of these so I'm willing to help you develop it. I'd roll and weld you a tube fit the cost of shipping if that will help you finish development.
 
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