Sand Pot, could it be a salt replacement.

It will be interesting to see how well your able to heat it with electricity. The math says it takes almost 27KW of power to equal 1gal of propane. We pay 9-10¢ a KW so it's about the exzact same price as propane per gal. The advantage of Electricity is you can seal all the heat in which makes it more efficient then if you used propane. But I'm wondering if you can overcome the heat loss of the exposed sand and then adding the steel to the mix. The advantage of propane is we can easily up the BTU/HR input. With electricity you have greatly increese the amps.

Just for giggles if we used say 2lbs of propane an hr (10hr run time on BBQ size tank) which I think is less then we would need but it's a starting point. 2lbs of propane is equivalent to 43,200btu/hr. 1KW is equal to 3,412btu/hr so This means you would need 12.66KW heating elements to equal the propane. This would draw 57amps of power on a 220 circuit. Now electric will be more efficient because it's sealed but I don't know how much more. Heat treat ovens are really efficient but thy are fully sealed where a sand pot is not. You basically have a 6" opening in your Sealed system. Yes we don't have much air circulation besides the air being pumped in from under the defuser plate. So even if it was say 30% more efficient then propane your still going to need 8.86KW elements and 40amps of power at 220.

All these numbers are based around my origanial assumption of 2lb of gas used per hr. I honestly think it might take more depending on how big it is and how much castable you got in there. 2lb/hr is quite good for a small forge and if you crank that small forge up to 11 your lucky to get 5hrs out of a 20lb bottle which is 4lbs/hr. If that is the case for this sand pot and it's not 2lb but 4lb/hr then you just jumped from needing 40amps to 80amps.

I'm not trying to piss on your corn flakes at all. Mostly just trying to see for my self how practical using power is with the limited power most shops have on hand.
 
Thanks Stacy, I'll make note of all of that.

Heating wise, this will be a fairly small pot. 3" pipe for the inner pot as that's what I had available. I figured I would start small, and most of what I make is tiny anyways. I'll leave enough space that I could fit a bigger pot in if it ends up being too small.
The electric is a trial of sorts, if it doesn't have the needed heat I'll convert it to a low temp pot for tempering, marquenching, and the like. I've got a much bigger piece of stainless pipe I could use to build a large gas fired pot of need be.

That small piece of pipe was free, and the pid, SSRs, and kiln elements were cheap enough that I figured its worth a shot.
Even if it totally sucks, I'll only have had about $200 in it including the refractory and wool.
 
I wish you good luck. I'm thinking about casting mine up this weekend as well. Or at least getting it set up to be cast. The issue is it's still to cold for casting. Wonder if the wife will let me do it in the laundry room lol
 
Worst case I make it a low temp pot, I'm sure I'll have enough power for that. This is as much an experiment as anything. I've got a 30 amp circuit for my welder, so that would let me get up to around (iirc) double the power of my evenheat. If that's enough to hit 1475 with a 3" hole in the top, I don't know. But I'm sure it would be plenty to hit 5-600. Either way I'll learn something doing it, and share the results for others who may want to try it.
I'm probably a month or so off building mine. I've got a belt grinder stand to build today, and a few knives that need to get out pretty soon. Get a few bills paid, and order in the refractory. It'd be nice to wait until its a bit less cold and rainy.
 
I post this in wrong thread ..............https://www.bladeforums.com/threads/wip-fluidized-sand-pot.1569133/page-2

But here all this starts :)
kuraki said:
The diffuser was the big sticking point for me in making one of these. I wonder if the expansion issue could be alleviated by bringing the air inlet in from the side and drilling into the fire brick so it terminated inside the brick rather than below it.

The other thought I had is remove it from the high heat chamber entirely and leave 4-6" of the tube that contains the diffuser outside the heat chamber. It will still get hot obviously, but maybe at that point you could hold 1850-2000 on the tube inside the chamber and only be 14-1500 on the diffuser portion.
Click to expand...
Well @kuraki........last two years I try whatever not for diffuser .Soft fire brick are not good /for me at least/ they make ONE big bubble come up AND every time in same spot on surface ...and no mix sand good ,have no idea why that is case ? And they break on high temp .I try ceramic filter ....works excellent but at the end break too ..........Now I think that I found best solution for this problem ,at least I think so :) Carbon ! I will not write to much because of my english .I try this on cold and this kind of diffuser mix sand perfectly ....really perfectly , small bubble come out in many places and there is ZERO resistance when I put steel in sand . Carbon is some strange material when it comes to heat ........Look picture , I can hold for hours that carbon cloth on flame and next second I can hold it with hand ....not even warm ??? I can even put my finger on that thin carbon cloth while is still under flame ,and there are only three layer cloth ??? For now I will try only with about inch thick carbon cloth layer between this two stainless plate .I m 100 % sure that temp under that two plate will be very, very LOW ! Tube is thin walled 3 inch dia. but it is seamless inconel .....once im my life I make some muffler for some bike:) That carbon cloth hold my 100 grit AO with only one layer and I think that should hold sand .....I will try this days how all would work with heat ....
carbon fiber diffuser :)
uzftMQC.jpg

2IUb83n.jpg

I try this even with big torch too.............no way I can heat all three layers.NOW I wonder if carbon is good for insulation HT oven ?????????
QZMDIR2.jpg

All this parts are stainless of course ... carbon cloth will be betwen this two round plate .....that three M6 stainless bolts are spacer for plate ,under that is air chamber ..

Qvxdm5O.jpg

rTWwM0L.jpg

qabeqI7.jpg


hole for argon or air..........
auq6Ybt.jpg

DkVbW7h.jpg

One picture will explain better than me with my english :(

TamOAI8.png


I don t know , for now I can t find why this should not work on HIGH temp for stainless ...

PS. I forget that in this thread we have this short video ......THAT is what i get too with soft fire brick ...........And I have no answer WHY ?

k9ez6hm.gif
 
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Natlek said:
.Soft fire brick are not good /for me at least/ they make ONE big bubble come up AND every time in same spot on surface ...and no mix sand good ,have no idea why that is case ?


k9ez6hm.gif
Click to expand...
I will quote my self :D Ok , today on a lunch break I ate only one sandwich....... something came to my mind and I had to try :eek: You know WHY bubble on this live picture come only in one place/location ? Because tube is not exactly in the vertical position . Thats it ..... that's why I have same problem.........I did not pay attention to it at all :mad: Even with this new diffuser I managed today to get bubble only in one side , just little angle on tube and ONE BIG bubble come out to say hello you stupid :D Obviously the air even in tube will not go aside but right up :) So I think that tube MUST be in a perfectly vertical position to get maximum in mixing sand .....

PS . I have no access here to kaowool but I think that will work in this my solution for diffuser ?
 
I m done with testing , it s time to build one .....
Tube is 20 inch long and 3 inch Dia. Filled with sand 16 inch from bottom .



I make only one hot test to ,without gas....About half hour in almost yellow color with small amount of sand inside .........I think that will work .Part with carbon diffuser is little jammed now. I will need assistance /tomorrow / to pull out bottom part to see what was going on .
nXtSkU1.jpg
 
I think it will quench faster with the air. Each particle of sand that come into contact with the blade will draw away some of the heat. So having billions of them constantly touching the steel then moving away will cool it faster than one static set of sand grains.
 
What is the maximum temperature the a propane heated sandpot can operate at with SiC? Can it be used for PM tool steels at 2150?
 
DeadboxHero said:
What is the maximum temperature the a propane heated sandpot can operate at with SiC? Can it be used for PM tool steels at 2150?
Click to expand...

Why SiC ? Max. temperature in sand pot depends on that which material you used to build , size of furnace and power of heat you have .I have AO sand which can withstand triple the temp then we will ever use in HT steel ?
About tube for sand pot ....Seems that Inconel 600 is what we need https://www.hpalloy.com/Alloys/hightemperature.aspx
 
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Why SiC, because I have a stock pile of it at 60/80 and 120/150for Waterstones.
Two for one. :D

I saw at Bladeshow West that Paragon was making a sandpot and had it on display. I talked to the Australian gentleman and he told me he was using SiC. I thought that was rad.

Anymore pictures of your sand pot Natty?



Natlek said:
Why SiC ? Max. temperature in sand pot depends on that which material you used to build , size of furnace and power of heat you have .I have AO sand which can withstand triple the temp then we will ever use in HT steel ?
About tube for sand pot ....Seems that Inconel 600 is what we need https://www.hpalloy.com/Alloys/hightemperature.aspx
Click to expand...
 
Youwhere at blade west and you didn’t stop by to say hi.
 
JTknives said:
Youwhere at blade west and you didn’t stop by to say hi.
Click to expand...

Yeah, bummed me out. I was pretty overwhelmed the show was a lot of information to take in.

I've been watching your videos, so now I know what ya look like. I'll be at the Eugene OR Show with a table.
 
I didn't know this was a thing until I saw this at Bladeshow West



I had no idea what this was till after the show. I thought it was "molten" sand till Larrin corrected me.



Met this Australian guy at the show. I thought it was really cool that it used 120grit SiC powder and wasn't as dangerous or as complex as the Molten salts. Also it doesn't need special high temp saltsfor stainless and pm tool steels

It's takin me a while after the show to realize what I was looking at.

Looks really interesting, I'll keep going through and reading this thread, lots of information here.
 
DeadboxHero said:
Anymore pictures of your sand pot Natty?
Click to expand...
Not finished yet , I put this project on hold for now .To much thermal mass to heat for one blade at the time . . . I would build something like this over winter. . .I will use electronic which I have for sand pot so n no additional costs .


PS. If you decide to build sand pot , maybe Kanthal have best steel tube for that I just found that . ..
https://www.kanthal.com/en/products/furnace-products-and-heating-systems/furnace-tubes/
 
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