Getting ready for first pour finally

So I bought a vevor furnace a year ago and it's just been sitting. Today I finally got around to lining it with satinite. Seems like it went ok, followed some information on this site and painted a coat on then fired the furnace, then repeat several times. At the end of the day I put the empty crucible in and heated everything up for a few minutes. Seems like everything held together.

I need to make a set of lifting handles and a pouring handle still. Also need to build a flask yet. I do have some questions.

I bought some premixed green sand a year ago. It's been stored in a 5 gal bucket with a lid on it. I'm assuming I might need to add a small amount of water back to this to make it right.

Is there an easy way to do this?

What sort of consistency am I looking for ?

I'll be pouring aluminum to start, probably chopped up automotive water pumps and the like. I poured an aluminum ice cream scoop way back in high school but we had a pyrometer.

Is there any certain things I should be visually looking for to judge when the aluminum is ready to pour?

Will I need to flux or otherwise add anything to the melt?

I'll be using the cheapo crucible that came with the kit for now. Probably first thing I'll upgrade.

Do you always empty the crucible on a pour?

Do you keep a spare ingot mold or something out to dump any excess in?

Would it hurt to leave material in the crucible?

After pouring do you leave the crucible out, or put it back in the furnace?

Do you start with what material will fit in the crucible, then add more as it melts down?

Excited to learn more about this and appreciate any help.

 

Use a flower mister/spray bottle. It often takes less water than you think. There are videos about green sand squeeze test on YouTube. You can mix green sand on a plastic tarp and let it dry out a bit if it gets too wet.

I pour extra aluminum in an ingot mold. I usually put the crucible back. I usually only have a thin skin to clean before next use. I have never left the crucible part full to cool off.

No flux. Charge as you described. A pyrometer is nice to have, there are some threads on building them on the forum.

 

Tops is exactly right. Look for Greensand squeeze test or greensand sausage test on YouTube. It’s very, very easy to over-wet it.

Don’t leave excess metal in the crucible ever. It is likely to expand and crack your crucible next time you reheat it. Pour out the excess immediately. It will leave a skin inside the crucible. That’s ok, but never leave a heel in there.

Steel cupcake pans make great ingot molds for pouring off the excess. Avoid teflon because the smoke is poison to any animal that breathes it, including birds. If you have nothing else, you can pour into a dog food or soup can. You’ll just have to cut it open afterwards with tin snips. What ever you decide to pour into, preheat it red-hot over the furnace exhaust to burnout 100% of the moisture and residue while your metal is heating up. Do this every time you pour into an ingot mold. Don’t forget.

After the last chunk is liquid, wait 4 or 5 minutes to superheat, then pour. You can refine this process later, but that should get you started.

Yes

Some put the crucible back into the furnace to cool down, some leave it outside. I haven’t been convinced that one way is better than the other.


Pete

 

Good luck on your first pour.
Be sure and pre-heat everything that the molten melt comes in contact with!

Here is how I judge metal temp. But, I know what my furnace/burner combo is capable of.
I place the crucible in the cold furnace and loosely fill with ingots/scrap. line the vent with the next pieces to melt.
Fire up the burner on low, when the walls are red, bring up the burner.
As the ingots melt and sink, keep adding the pre-heated pieces.
When the crucible is 3/4 full and the last ingot goes in, I will watch it melt. When it flattens out on the surface (completely melted), I start a timer on my phone. When the timer goes off, turn off burner, remove lid, skim, remove crucible, transfer to shank, another quick skim if necessary and pour. Probably no more than 10 seconds between removal and pour.
I'm a firm believer in pouring as cool as possible so each of my patterns have their own time.
A short, thick pattern is 1 minute on my timer. A 1/4 x 8 x 16 plaque is 2 min 30 seconds. My longest heat has been 3 minutes. Small lost foam pieces are usually 1 1/2 minutes. I increment/decrement by 15 second intervals.
The longer your molten metal is exposed to the furnace atmosphere, the more chance it has to absorb hydrogen (porosity). Keep your burner tuned lean. If you have flame exiting the vent, you're running rich.
After the pour I turn the crucible upside down to cool outside the furnace.

 

Thanks for the insight, I'll just have to get some experience and see what happens.

I'm sure it's completely dependent on the actual burner to the point you guys can't really tell me... but does anyone have any idea on what pressure I should be running on the propane?

It came with a 0 to 30 regulator i think. It's a two burner vevor furnace. Simple jet in tube type burners. This set up didn't come with air sleeves on the tube's, my forge has them but not this furnace. Might have to build some so I can tune the flame better.

 

Been busy today building the tools needed to actually pour.

Took the cheapo tong things that came with my furnace and modified them to make a crucible lifter. Still kinda flimsy but better than channellocks. Not much room between the furnace and crucible for tools, but I think this will work to get started with aluminum.


Made a quick pouring shank out of 5/8th rod. I'm not sure if this really needs a hook to hold the top of the crucible. Seems I can turn the crucible almost all the way over without it falling out. I'll probably add one anyway.


Welded up a few ingot molds as well.

 

Nice work on the tools and ingot molds,.
My furnace came with the same tongs and only about 5/8" (14mm) clearance per side with my biggest crucible. Your results inspired me to make a new set with 18" [45cm] straight handles.

 

As others have said, always empty the crucible before cooling down, otherwise the metal is likely to fill the space, and then when you heat it it expands and CRACK.

For startup, one of the crucibles we bought back when I taught metal working came with recommendations:
Start up cold, with a small lump of metal in the bottom, enough that when it melts it will create a puddle about half an inch deep.
Once that is liquid, add in additional metal.

Have followed more or less the same procedure since, with good luck.

In any case, definitely don't jam your crucible full with cold metal, or you could suffer the same expansion problem as mentioned at the top.

 

When melting dirty scraps, I tend to add potassium chloride in the form of low sodium salt (or as Joe Bang would call it, "fake salt").
Seems to cut down on the amount of metal that sticks to the dross.

 

Well just finished turning an old water pump into some ingots. I won't say it went flawlessly, but no injuries and no explosions so overall I'll call it successful.

40 minutes from light to done so that wasn't bad, and I was running the burner at less than 10 psi. I filled the crucible fuller than I was really comfortable with so I will have to watch that in the future. I also ended up with more metal than I had ingot molds which was cured when my crucible tried to fall out and spilled the rest on the floor. I think I need to open the ring on my shank a little and guess I do actually need a top hook. Also forgot to find a skimming spoon so had to use a random piece of metal.

Like I say not flawless but nobody died.

 

Knocked the ingots out and threw the spilled stuff back in and was ready to pour just two little ingots in a few minutes. Opened the loop on the shank and that worked better.

 

At this stage of the game it's a learning experience.
It'll get easier as you go.
One down, hopefully many more to go!
Slice an ingot open and check for pores. No pores = good burner tune.

 

Ahhh…. Looks like we’ve hooked another one fellas!
Pete

 

@FishbonzWV I actually did just that yesterday. The bandsaw didn't cut it very well but it looked solid.

Now I need to get a flask made so I can pour something useful.

 

The aluminum piece cut on the bandsaw, the cut faces can be ground and sanded working from coarse to fine for a better look.

Did somebody say flasks? I need to sort through mine today for tomorrow's pour. I think I like making the 'stuff': patterns, flasks, match plates- about as much as I like making the castings themselves.



I use the ones on the right and the ones on the left most. The two center ones with metal alignment hardware have yet to be used, the one is way too big and the other I just have not tried yet. The far left one with three pieces of wood (long ones on cope, short one on drag) as guides is about the easiest to rig. The next one over is pinned with 1/4" (6.4mm) dowels. The far right are CNC cut plywood (could be cut by hand as well) that have internal 1/4"96.4mm) pins to run match plates. There are two metal buckets full of sand off camera for lost foam, their soup can pouring aids made the picture. The tape dispenser reels and the whale mold were CNC-milled lost foam pieces.

 

Yeah but that word will be pluralized in no time.

 

I assume 1x pine is acceptable for flasks. No real need to go to 2x?

 

I'm not sure what to think of this crucible. It's covered in these little cracks (crazing I guess). This is the crucible that came with my furnace so I'm sure it's the cheapest of the cheap. I was hoping to get a couple of uses out of it before ordering a better one. Is this just something that happens, or did I heat it to fast, or? I tapped it with a plastic hammer. Doesn't sound any real different than when it was new. Course it didn't really ring when new either.


Filed the ingot a little to better show the surface. Seems nice and solid.

I see I have a couple of cracks in my furnace lining. Maybe I didn't fire it enough between coats? Oh well I have lots of satinite left so I can always reline it if it gets to bad.

 

The crucible is just a cheapo crucible, it's made with lumps of recycled fired clay mixed in that contribute to cracking. The lack of a glaze that quality crucibles have also reduces the life by allowing metal slag to erode it. A few crack in your furnace lining is normal too, they can be patched if they get any larger. Congratulations on your first melt too!.