Sawed off cupola

[vtsteam]

CO2 and CO are organic compounds that are off-gassed during partial combustion of coal. And charcoal.

Graphite has recently come into favor in commercial practice for replacing sea coal to reduce unwanted emissions. Graphite is pure carbon.

Most references I found online said seacoal was used to produce a reducing atmosphere. There was not specific mention of the need for VOCs to do that, just a reducing atmosphere,.....which a mix of CO2 and CO would produce, since they have absorbed and continue to actively absorb oxygen.

I'd still like to hear from Ironman on this, or anyone who has actual experience using charcoal in greensand for iron casting.

[ironman]

vtsteam Charcoal will not do anything because as awemawson has said it burns and forms a gas  layer.

I used to add coal dust to my sand after every melt but I don't do it anymore. Each time the cast iron burns the coal dust it turns to coke which is an inert byproduct that I don't need or want in my sand. The sand becomes very brittle after a while and so more bentonite has to be added to give the sand more strength.

 I now make a facing sand with coal dust and use it to cover the pattern only so the sand lasts for many years. When I added coal dust to the sand after every melt I would throw out the sand about every 12 months.

If you want to don't use any additives and just wire brush or sand blast the castings

[vtsteam]

Thanks Ironman, so coal only in the facing sand. That is easier for me to come by, since I have some coal that I can pulverize, and I wouldn't need much of it

I'm still confused about the charcoal since all of the online talk is that you want a reducing layer of gas between the metal and mold surface to get a good finish, and that seacoal produces it. But charcoal also seems to produce it, but now it is seen as a negative. Maybe because it burns more easily, and produces too much gas? Would reducing the amount help that?

Anyway experience is more important than theory, and you have that, more than most people doing iron on the scale we are interested in. So I won't add coal or charcoal to the molding sand, but only to facing sand.

I suppose I could do some small batch experiments with various amounts of ingredients just to satisfy my curiosity about all of the above. I also have some plumbago (graphite) that I could try. Since it doesn't have to be in my main casting sand, there's less of a concern that I'm going to wreck it all by mixing in the wrong ingredients right now at the start.

[vtsteam]

One more accidental addition to the gear....the propane torch I'm experimenting with in another thread -- trying to get it to braze -- no good for that so far, but would probably work fine as a ladle heater.

[ironman]

I was about to suggest doing experiments to see what works and what does'nt, that is  the way I learnt. We all come from different parts of the world so what we use may not the same and give a different result.

I have heard about this method but never tried it, is using CO2 gas from a bottle and filling up the mold so there is no oxygen left. The castings have a nice colour and skin because there is no air to oxidize the surface.

With your ladle heater it might be easier to place the ladle on top of your exhaust vent to recover the waste heat coming from your furnace. It also means you do not waste propane heating your ladle. I wanted to try this method with my own cupola but my the ladle was too heavy to lift to the top so I scrapped the idea because of safety concerns.

[vtsteam]

Thanks Ironman. I just ran across a reference in Stewart Marshall's book to yet another facing dust -- from store bought charcoal briquets. He doesn't like them for iron use otherwise, but mentions the dust  So maybe I could try a test of all 4 types of facing powders in sand so far mentioned and see what happens.

I had thought about an exhaust ladle heater, but when I saw yours in action it was glowing really yellow, and I was wondering if the exhaust from my sawed off cupola with a lid could really get a ladle to glow.

Definitely would be nice to save propane if possible, so just one more thing to find out.

[vtsteam]

Rain stopped this morning, I think we got 8" total since last week with 1 day of sun.

Thought I'd try to fire the cupola lid a little harder with a propane weed torch, but the thought of dragging a full tank 300 feet up the saturated hill wasn't apealing.

I remembered the wheels and handle I'd taken off of the cupola shell (it was originally a commercial vacuum cleaner), and decided to make a oxy-propane welding cart with the remnants. A little rebar, a cutoff of 1/8" sheet, and an old discarded toolbox were assembled, and I tried out my oxy-propane rig for the first time as a cutting torch by simply changing the cutting tip. It cut the sheet and rebar easily, so I'm very happy with the changeover from acetylene.

Everything that went into this was a discard -- the wheels and handles twice over. The rebar was just short cutoffs, so I welded them together to get a usable length. In short, this is a total work of scrap!

It rolls and balances very well, and I may actually take a grinder and a paintbrush to it to give it some respectability. It sure is nice to have -- Just as I finished taking the picture a monster gray cloud rolled up and it started to rain again.!! But wheeling the rig back into shelter was the work of a moment and It was very pleasing to be able to do that.

[dsquire]

VT

Darn it, you would be a handy guy to have around my junk treasure pile. 

It's a good thing that you and Rob Wilson are on seperate Continents. I can't imagine what we would all see if the two of you got together. 


That cart looks pretty darn good. With a lick of paint nobody will ever know where it came from. 


Cheers 

Don

[NeoTech]

So now we should start the get the madmodders onto the same scarpyard project? ;)

[awemawson]

I reckon your next project needs to be a Funicular railway up that hill of yours - save all that hassle 

[vtsteam]

Thanks Dsquire -- Rob has some pretty talented friends over there already -- apparently involved with tool grinders at the moment! Did manage to add a fender under the hose to prevent rubbing, grind some of the worst looking parts and empty a spray can of paint at the thing, before the honey-do list ad to be attended to -- since we actually had sunshine all day. Basically I mowed with a push mower from 2:00 to 6:00 PM. Grass was 6 " tall -- where it was low!

Sure Neotech, join in the junkyard fun anytime!

Awemawson, I wish -- that would be fantastic. I've dreamt of a scenc railway through this property. But funicular in spots, for sure!

[awemawson]

Basically I mowed with a push mower from 2:00 to 6:00 PM. Grass was 6 " tall -- where it was low!

I'll lend you some sheep if you like 

[Rob.Wilson]

Hi Steve

Thats a nice compact set you have there  , thinking of doing similar , due to space and cost of fuel gas .

I may go down the Propane route too .


Rob

[vtsteam]

Basically I mowed with a push mower from 2:00 to 6:00 PM. Grass was 6 " tall -- where it was low!

I'll lend you some sheep if you like 

That would be great! Sheep are making a comeback here after wool industry collapsed many moons ago. Specialty cheeses are the reason. Guess I'd have to figure out what to do about Eastern Coyote (wolf mix) which are also new upon the scene. Our little mutt is half border collie, but half dachshund, so he'd basically make a meal for them!

[Mayhem]

Throw a couple of alpaca's into the heard - they protect the sheep from canine threats.

[vtsteam]

Hi Steve

Thats a nice compact set you have there  , thinking of doing similar , due to space and cost of fuel gas .

I may go down the Propane route too . Rob

I like propane a lot, Rob, now that I've tried it. Took me a bunch of cuts to understand the difference. Preheat is a little longer, but not much -- but you do need to keep the flame about an inch above the cut to preheat, not touching the blue cones as in Acetylene.

But you lower when you hit the oxygen to normal cutting height -- didn't realize that at first and so was interrupting cuts. Makes sense now because, of course it's the oxygen jet that cuts, not the propane (or acetylene). 

I like the compactness of the rig, too -- and there is 170 cu ft of propane in there instead of the 40 cu ft of acetylene in the B size tank that matches the oxygen tank. Plus propane is 2500 btu/cu. ft, and acetylene is 1750 btu/cu ft. Costs the same to fill the propane tank as the B size acetylene tank, and much more widely available. Also just a lot more stable a gas than acetylene, with its tricky storage medium and critical flow rates. so generally I feel better about just having a tank of it around.

Changeover for me was just buying a T rated hose ($35) and a propane cutting tip for my torch ($15). I had a spare acetylene gauge which I'm using. I've kept my acetylene tank in case I want to flame weld, but if that doesn't happen often enough, I'm thinking about trading it in for a second oxygen tank.

[vtsteam]

I got a chance to work on a tuyere for the cupola today. I took an old piece of 2" pipe with an elbow attached that I had found half buried in a field . It was well rusted together, and filled with dirt.  I sawed off the pipe to a 3" stub. Then welded  a bandsaw cutoff from a 1-1/2" pipe with threads to the elbow. That made it into a Tee and will serve as a peep hole. I cut out the connecting hole through the elbow inside the new fitting using the oxy- propane torch.

Then I bent a piece of 1/8" plate to fit the barrel curvature, and burned a hole in it. I then welded the tuyere to the plate. The plate will serve as a mounting flange to attach to the furnace barrel. The barrel skin is very thin stainless and I'll probably rivet the tuyere plate in place. This is what it looked like, and a pic of test fitting it in place on the furnace. It isn't attached yet. A thunderstorm came up and I had to get tools under shelter.

[vtsteam]

Riveted the tuyere on tonight and patched the lining and lid.

[vtsteam]

Sunsine!!! This morning I decided to try to fire the patched lining and lid, and to do that I would try using my new propane burner. I  took the oxy bottle off of the new propane cart and wheeled it up the hill to the furnace position in what was once cleared dirt, and more recently, mud. But today with the sunf and a breeze, the mud dried up.

To fire it I also needed a prop to keep the cupola doors shut, so I welded a length of chain onto a section of 2" pipe, and scrounged a square of 1/4" plate as a base. I didn't weld this to the pipe because I think it would more likely hang up that way.

Anyway, I got everything set up, dialed 5 PSI on the gauge, which seems to be a nice even flame for this burner. The Mako burner, which this one is similar to, has a range of 5 PSI to 15 PSI. I wasn't in any hurry to fire the lining, and I've never had it up to 15.

I just propped the burner in the cupola's tap hole and there was a muffled roar, much quieter than running a blower with charcoal. I figured I'd run it an hour.

[vtsteam]

Naturally as soon as you start heating up a furnace, you think, why not use that heat? I didn't have a mold ready, and the sand isn't in condition anyway, but I figured I might try to melt a chunk of aluminum that has been a challenge to my bandsaw. Not the best stuff for casting -- 6061 t6 I think, but I might be casting some flasks like ironman's, and surface finish wouldn't be important. Some of the best structural aluminum types are not too pretty when cast.

Anyway I figured I'd take this recalcitrant 4 pound chunk and see whether I could reduce it to muffin ingots. The darn thing would hardly fit in the pot!

[vtsteam]

And it fought bravely for about an hour, but finally succumbed to gradually increasing furnace temps. I have 4" thick walls and lid, so the furnace has a fair amount of heat inertia. And with a modest burn rate set on the propane burner, I didn't expect to set any records. But it definitely turned into a full to the brim pot of the silvery stuff, and poured nice as you please into 9 muffins. 

Well that just fired the enthusiasm up, and I repeated the same thing with another chunk that might have been its twin brother.  It melted in half the time with the furnace temps up. By the time two hours was up I had done four melts -- the last were pieces of a Chevy bell housing and a heavy cast aluminum tray from the thrift shop. These, having been cast items made much better looking aluminum than the 6061 had. All in all about 15 pounds of muffin ingots.

[vtsteam]

Well things were going along great when my 6 year old daughter came up and said, Daddy do you think you can make a picnic table in 5 days?

Sure, I said, I promised you. Her birthday party is coming up and she said she wanted a picnic table from me as a birthday present. Unusual level headed and practical 6 year old!  She also has her mothers sense of urgency when it comes to chores.

Seemed like the furnace had baked long enough, anyway, so I turned off the burner and checked the tank. Not even cold. No condensation, and at least a half tank left. Pretty economical, I guess -- I don't know. My first experience with propane in a furnace.

So switched gears, drove an old pine log onto the sawmill with the cant dog. Slicked off the bark with a flat shovel, poured about a cup of gas into the motor, turned the stopcock, gave it the choke and it started instantly. First pull. As if it hadn't sat all winter.

I did a rough job on the boards -- blade needs sharpening after sitting, but I got it done. By afternoon I was bolting the table together.

Good day! Nice to see sun again.

[vtsteam]

Made another load of charcoal today. Made up the sand bottom in the cupola. Lined the breast with refractory and lined the spout. Checked the ladle fit under the spout.

[Mayhem]

Looking good VT - is the chain to pull the doors or to keep the guard dog in close proximity.

[vtsteam]

It pulls out the prop holding the doors shut.