Foundry.

[brightspark]

I do this and it's great but keep some even smaller bits as it takes forever to melt a crucible full of ingots.

place some ingots round the crucible top in furnace and they can be pre heating while the metal inside is melting then just pop a few in till full

 

[grim_d]

place some ingots round the crucible top in furnace and they can be pre heating while the metal inside is melting then just pop a few in till full

Yeah I already do but it's still better with some smaller chunks, Ive thought about getting a cake pop tray to make mini ingots.

 

[captain-destructo]

when i said cake tray i didn't mean Christmas cake size

i was thinking more one mouthful size cakes

 

[Kram]

Mine is swiss cheese. Probably too hot as it was glowing orange. Lots of holes doesnt machine well.

Tuna tin, it will go easy into lathe chuck, but not so great if need to remelt.

 

[DAPPH]

Kram , Did you add any flux such as borax or SIF flux to the mix before you poured it to bring the impurities up to the top of the melt in the form of dross.
Plus did you add any of the de bubble chemicals to get the air out ?

For a remelt can you not turn off the can covering & face it off at the bottom & top if it fits in your lathe ? Was your tuna a can dishwasher clean & bone dry before you poured the molten aluminium into it ?

Finally was it pure aluminium or an aluminium alloy mix ?

 

[Kram]

I did not know borax is suitable for aluminium? Indended to use the salt mix to degas but couldnt find it.

Can was clean and I burnt the coating off. Got a stainless thermal mug/containers and a muffin tray to pour into next time.

It was a mix of some engine casing, extruded scrap, motorcycle parts and a cheap chinese tube bending tool.

I want to buy a parrafin torch/stove and use that as an burner

I weighted them 640g total. After turning 413g as they were not on a flat surface.

 

[DAPPH]

See if you can find anything of use in this site .

http://www.alloyavenue.com/vb/archive/index.php/t-2382.html

 

[grim_d]

So I've done 10+ melts now, I'm on my second 19kg propane bottle and I still haven't achieved what I set out to do.

The end of the tube inside the foundry has all but disappeared now and the end of the burner itself is taking a bit of a beating.

The refractory is starting to degrade a bit too though is still holding together.

Through a combination of degassing, fluxing and adding boron nitride I get material that has a reasonably tight grain structure and only the tiniest speckles of porosity. It doesn't machine particularly well bit with high SFM and a light cut it can be acceptable. I am exclusively using alloy wheels at the moment.

My biggest hurdle is casting a blank for my gear, I need a disc that is 240mm x 25mm to give room for cleanup. My crucible only holds just enough to achieve this.

I have tried 6 times to make this and each has been a failure of some description though came very close this week, just 1mm too small.

My two most dramatic failures are when there is too much moisture present in the sand and it turns into a bubbling mess of molten aluminium. I've tried drying the sand with the burner before pouring which is hit and miss.

Ideally I need some sort of steel form that will give me a perfect blank, if I had steel that big though I'd just make the damn gear from steel...

 

[Wendelspanswick]

So I've done 10+ melts now, I'm on my second 19kg propane bottle and I still haven't achieved what I set out to do.

The end of the tube inside the foundry has all but disappeared now and the end of the burner itself is taking a bit of a beating.

The refractory is starting to degrade a bit too though is still holding together.

Through a combination of degassing, fluxing and adding boron nitride I get material that has a reasonably tight grain structure and only the tiniest speckles of porosity. It doesn't machine particularly well bit with high SFM and a light cut it can be acceptable. I am exclusively using alloy wheels at the moment.

My biggest hurdle is casting a blank for my gear, I need a disc that is 240mm x 25mm to give room for cleanup. My crucible only holds just enough to achieve this.

I have tried 6 times to make this and each has been a failure of some description though came very close this week, just 1mm too small.

My two most dramatic failures are when there is too much moisture present in the sand and it turns into a bubbling mess of molten aluminium. I've tried drying the sand with the burner before pouring which is hit and miss.

Ideally I need some sort of steel form that will give me a perfect blank, if I had steel that big though I'd just make the damn gear from steel...

Have you tried Carbon Dioxide sand casting?
You add sodium silicate to your dry sand, pack it round the pattern as you would do with a green sand casting then inject carbon dioxide into the mould, this bonds the sand together.
You have no worries about moisture in the sand then.

 

[grim_d]

Have you tried Carbon Dioxide sand casting?
You add sodium silicate to your dry sand, pack it round the pattern as you would do with a green sand casting then inject carbon dioxide into the mould, this bonds the sand together.
You have no worries about moisture in the sand then.

I'm reluctant to throw any more money at this and don't have any co2, I'm also doing open casting, it wasn't about money to begin with but eventually one must draw the line, with what I've spent now I could have bought 5 plates of aluminium the right size.

I'm tempted to sell the burner and foundry and just buy some stock as casting isn't something I've found particularly enjoyable. I did want a propane bottle anyway as I'd like to get some heating gear so no loss there.

 

[DAPPH]

if it is a one shot cast make your own crucible big enough out of thick walled steel & weld on a bottom turn your mould up out of blue polystyrene insulation & glue it to make greater thicknesses the hot pour will melt it out the mould . kiddies play sand LIGHTLY sprayed with a trigger pack of water as you pack it round the form worked for me .

 

[Kram]

It might be a bit flimsy at that size but I was casting into steel tins. Cake tins that size are cheap. Sand the coating off, sink it into your sand so that it has support. Position some steel tube to reduce the volume you need to fill?
Thread needs more pictures. I want to do some casting but no time...