Propane tank/fueled furnace build

Hi All

New guy here and after having done the introduction thing over in the New members area, I thought I would get into my furnace build here. I have been asked these questions.

Questions from Jason...

You've picked a metal, that's a good start! Yes , Aluminum
Now pick a process .... sand casting
..pick a fuel source for your furnace. Propane
Buy a crucible for the size you plan to melt. (Clay graphite, Silicon carbide, ceramic) I thought I would make one to start with a 6" steel pipe.. bad idea?
Furnace.. Make it myself
Furnace Construction - kaowool and a lightweight coating($), or kaowool and hard face refractory($$) And this is where my serious confusion starts...
Tools - Buy online($), make your own Have lots but yes to both options, depending on what I get into after having castings to work with.

you wouldn't do it to cast a big lump of stock to turn in the lathe....mmmm that is exactly what I want to do....

Savvy? I do highly recommend get a crucible (clay graphite) now... OK, will go look at them. What are the benefits of a clay graphite over a home made (welded ) steel pot? But I will look at the sizes and build accordingly.


...., ask questions and be careful! Hence, I am here!

So, a couple questions above, ie the steel pot versus the clay crucible.
Where I live, fire clay is difficult to find... I tried ordering some a few years ago (I actually started then but then the furnace got shelved) from a local supplier and ended up with a 50 lb bag of Heatstop 50. I am not sure if this is usable for the refractory in the furnace. From their website, they show a castable product that might be better. the Heatstop 50 will work for laying the bricks for a pizza oven next summer though. I was looking for the fire clay to mix the home made refractory perlite, clay, portland and water.

http://www.backyardmetalcasting.com/refractories.html

I see furnaces with the insulation around them before the refractory, and some, like mine (an old propane tank) just built with the refractory poured in... I would think you want an insulating refractory of some sort, hence the perlite version, but then I see some sites where it says the Perlite breaks down...or maybe that was vermiculite....

I am not too concerned about the burner. They are all basically the same idea and I am comfortable with that. I have a tiger torch and will just replace the torch with the connecti0n to the burner.

So, where I am at now is either the homemade refractory mentioned above, although the clay will have start as cat litter and get ground up or, Home Hardware carries a castable refractory..

https://www.homehardware.ca/en/3lb-castable-fireplace-cement/p/2045281?page=search-results page

I am fine with that but wondering if I mix perlite with it for insulating qualities or use it straight up? I calculate that I need about 0.3 cu feet for my design and wondering how much that 3 lb container makes. I could not find it . Anyone know? I guess 3 to 4?

That is quite a lot for a first post. I think I will stop my babbling there, and perhaps work on the container a bit so that I can post some photos going forward.

If I have not lost you, Thanks for sticking with me..;-)

 

I would abandon the DIY refractory. Theres commercial stuff available that's proven. Even though HomeHardware calls it refractory, dont believe them. Outside of insulating or dense firebrick you will (most likely) not find anything suitable at a hardware store or fireplace shop. It's just not made for what we do. If I were to start over again, the satinite/kaowool furnace would be my pick hands down. Reasonably inexpensive, lightweight, durable, and effective.

Pete

 

IIRC, you said you were in Northern Ontario, how far is the nearest good sized city? Most cities that have any sort of a mining industry would have refractory suppliers.

 

Winnipeg 8 hours, Sudbury is 12 hours but they are a mining town, Toronto, 16 hours, Minneapolis (if and when the border opens..) is 6 hours. I don't mind ordering, but want to have a good plan in place first

I think I am formulating a plan...tell me what you think or if I have my products mixed up...

Line the tank (12" propane tank ) with 2" of Ceramic Insulation, then mortar over it with about a 1/4" of the satanite.... if I can get it? What are the opinions on the ITC 100 HT?

(International shipping costs are a lot so trying to stay in Canada)

https://www.amazon.ca/Owlhouse-Insu...cphy=9001161&hvtargid=pla-1060416999111&psc=1

But, Canadian Forge looks like they would have everything once I make a plan... https://canadianforge.com/collections/refractory-supplies/refractory-supplies?sort_by=

And Satanite here... although out of stock https://canadian-artisan.com/satanite-refractory-mortar-1-lb/

On that page, it states that 2 coats is best but that is still only about a 1/4" of refractory ? That seems like it would be fragile when just spread over a wool product. This is some of the confusion for me. That site is for a knife making forge, not a furnace.

The inside of the propane tank is 12" and I expect about a 6" wide crucible (not sure why that size..just what I am picturing ) . I am thinking 2 " walls, leaving an inch between refractory and crucible. Does that sound reasonable?

I have read mixed reviews on whether a rigidizer is necessary and or worth it.

As far as I got so far today....

 

Thunder Bay? I'm pretty sure you'd be able to find a supplier or two there.

 

When I was looking for products a couple of years ago, no one could supply what I needed or wanted but at the time, I think I was mostly interested in fire clay to make the refractory mix. Pantene said they could order the fire clay but after several weeks of delay, had a plain brown bag of something that I picked up. By then, I had moved on to other projects and only recently opened the plain brown wrapper to find they had sold me the Heatstop 50...

Now that I have learned a little more in the last few days, I will try again. I think the market is improving too as more people are looking into pizza ovens so insulation and refractory might be more available now than it was then.

 

How about Brock White? They've got a Thunder Bay location.

 

I think I tried them last time and they said no. In fairness, I think I was only asking about fire clay back then as I was going with the home made refractory back then. Now that I have been convinced to use something commercially prepared, I will call around this week to see what is open and perhaps I can find a supplier. Thanks Rocco

 

Good Luck, keep us posted.

 

Jeff

Thanks for the input. I will PM you.

Cheers,
Shawn

 

Ceramic wool is no problem up here, I think Jeff was excited about the prospect of ordering stuff from Budget Casting.

Just out of curiosity, does anyone here know how big a standard sized bag of Satanite is? There's an HWI distribution warehouse less than 10 minutes from my house, they probably have Satanite there but I'm willing to bet 5lbs bags are not an option from them.

 

That's what I was thinking too, the last time I bought refractory, about ten years ago, everything seemed to be 55lbs back then, I bought 3-55lbs bags of Plicast LWI24 Al-Tuff for $34 Cdn per bag ($100 minimum on cash sales), I wonder what inflation has done to the prices since then.

 

It seems that a lot of suppliers in my city are closed for either the holidays or the COVID lockdown initiated Dec 26. I have not made headway on the insulation but do have some Satanite coming. In the meantime, I have started looking at burner designs. In the book readily available on line, The Hobbyist Guide to Casting Metal, instructions are very complete for burner construction. pdf of the burner page is attached. My question is this. I have seen a tee version of this, where the inlet reducer is replaced with a tee fitting, in this case, 1/2". Is there a preference of one over the other? In the tee version, the gas orifice is mounted in line with the burner pipe. See, as an example, an attached image stolen from internet....
The book states a .025" orifice with the 1/2" pipe. Other plans have suggested .o30 but with 3/4 pipe, iirc. The book gets into ratios of fittings, pipes, etc. I figured I would start with the 1/2" pipe and see how it works. I am leaning to the tee version cause I think it would be easier to tune it by using pipe caps and slots cut in the pipes. A picture will follow when I get some done of my own stuff

I should add that I ordered a crucible but already think that it will be too large for the finished furnace. I might have to save it for my next furnace. I worked backwards from what I want to cast with the furnace and this crucible seemed about right. With 2" of insulation, then the satanite, I will only have about 1/2" around the crucible. Too tight? I can just start with a steel pipe as per my original plan, then buy another crucible if everything else is working out for me.

https://www.amazon.ca/gp/product/B07GT5SRDM/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Cheers,
Shawn