Small casting (alluminium) aty home.

[Tom Watson]

I would like to have a go at casting a small IC crankcase. I don't want to invest in a big furnace. How can I melt a small amount of aluminium at home.
Any suggestions. I have a small brazing torch that has oxygen and propane.
Thanks

 

[Tom Watson]

I would like to have a go at casting a small IC crankcase. I don't want to invest in a big furnace. How can I melt a small amount of aluminium at home.
Any suggestions. I have a small brazing torch that has oxygen and propane.
Thanks

Well I just looked a few posts down and most of my questions were answered. I will spend a bit of time going through this thread

 

[Vietti]

I suggest not overlooking pot metal as a casting material. Early pot metal got a bad reputation because it was unstable and broke down over time. Modern alloys like ZMAC are stable, melt at 800 degrees, are nearly as strong as cast iron, machine beautifully and make good bearing surfaces. Except for weight whats not to like?

There was an article in MEB some years ago discussing aluminum molds for the metal. The key was using proper release coatings, it works very well and no sand! The metal can be melted in a pot made for melting lead. I have used it to cast many magneto bodies.

John

 

[ddmckee54]

I would recommend checking out some of the home/backyard casting forums, thehomefoundry.org is a good one. Aluminum CAN be melted in an old cast iron skillet over a wood fire, not recommended - but it can be done.

There were a series of Gingery books that I believe were written in the 60's. These books deal with build the machines for a small home machine shop using hand tools, stuff that anybody could get, and home cast aluminum parts. The first Gingery book deals with building a foundry and making patterns. His refractory recipe is usable but won't last too long before needing repairs.

A foundry doesn't have to be big and or expensive. A large metal flower pot for a shell, either some fire brick or castable refractory for the lining, a small cast iron pot for a crucible, some charcoal, a hair dryer for a forced air source, and you're in business.

Don

 

[SmithDoor]

A Aluminum Found at home is easy.
First melt Aluminum can be as using pipe for curable and a charcoal for the heating.

The sand if get lucky is out of backyard aka nature bonded sand.

Parting powder is baby powder for Walmart.

The pattern can be as simple as old part being duplicated and molding clay from art supply or toy section section of walmart.

Then just takes practice.

Dave

I would like to have a go at casting a small IC crankcase. I don't want to invest in a big furnace. How can I melt a small amount of aluminium at home.
Any suggestions. I have a small brazing torch that has oxygen and propane.
Thanks

 

[SmithDoor]

If will help I had a foundry for manufacturing and sold with my business.

Dave

Well I just looked a few posts down and most of my questions were answered. I will spend a bit of time going through this thread

 

[bmac2]

Hi Tom. Oxygen and propane is way too hot as well as being expensive to run for melting aluminum.

Have a look at a thread I did on my first furnace and burner I put together back in 2014. The furnace is made in a 1.36kg coffee can with a mix of Fire Cement and Perlite and will do about a 5 pound melt of aluminum in under half an hour from a cold start.

The burner and furnace was fast, easy, cheap to build, and uses only common hardware store materials. It was never meant to last forever but ironically I still use it from now and then for small melts. Every time I start thinking of binning it I just patch it up and put it back on the shelf.

Mako Burner

On to the one thing where I think most people fail . . . green sand. Making your own green sand is not magic and can be done successfully if you avoid the most common mistakes I see on the internet.

1 Don’t use Home Depot like play sand. It’s great for a sand box for the kids bit it’s more like fine gravel and unless you’re willing to buy twice as much as you need and spend hours and hours sifting it you’ll never get a nice finish with coarse sand. Instead get a bag of medium mesh silica free sand for sandblasting. Locally I pay around $5.00 for a 50lb bag, less than the cost of 2 bags of play sand.

2 Don’t waste time on kitty litter. Again you’ll spend hours crushing it up and trying to get your sand to work, bin there done that. Look for a pottery supply shop. A quick search I found Blackwattle Pottery Supplies in Sidney. They have Bentonite clay at $6.60 per kg. I don’t know what kitty litter costs but if you can get the real thing for only a couple of bucks more. . . .

Watch out for baby powder most of it these days is corn starch not talc. I used some the other day without looking at the label and it does work as a parting powder but makes a mess of your sand. Fortunately those handy potters use talc in some glazes and at Blackwattle its $7.70 per kg. Make sure you wear a mask using talc there is a good reason baby powder switched to corn starch.

Have fun and don’t forget the PPE!

Oh ya. Don’t melt pop cans you’ll get nothing but a pile of dross (slag) and the aluminum you do get is not very good. Anything that is cast (car parts are great if you can get a hold of it) but even all those short leftover bits in your scrap bin or that bent ladder will be better.

 

[timo_gross]

I have not much practical experience, but as far as my information goes.

If you want to get going quickly and without doing much, here is what you need:

• I am not responsible for this, do not do it at home (go to your neighbour, be careful with toxic exhausts and explosive mixtures)

Charcoal with blower also works, but is more work to clean after you are done ( Carbonmonoxide sucks, beware!).

• BBQ clay pot. ( if your budget is enourmous you can buy more than one. One as oven, one as cover one backup.

It is horribly inefficient and gets hot on the outside. I guess the coffee can versions are much better, but cause more work. This is plug and play, and gets the job done quickly for 10 USD from the local household supply. (24h shop).

• A suitable clay graphite crucible starts from around 10 $ and will last a while.

Iron dissolves in Al (google phase diagram Fe-Al when in doubt), like sugar in water. Iron (steel) is not a clever material for storing molten Al.
Nothing about melting temperature. ( dump sugar cube into coffee, you understand what I mean )

• Use Al-Si variety special casting alloys. It just works better.

Someone I trust, as he works for the Industry, strongly advised me not to use extrusions, forgings or Soda cans.


Greetings Timo

 

[Tom Watson]

Thanks for all of your advice guys. I think I will look for a small ready made crucible. I have spent enough on this crazy hobby, a bit more wont hurt!
Regards

 

[Tom Watson]

This one looks OK. What does everyone think for a beginner?

 

[vederstein]

Here's how I built my aluminum foundry:

https://www.instructables.com/Aluminum-Foundry-1/
Now a couple of videos:

 

[SmithDoor]

This one looks OK. What does everyone think for a beginner?

Looks good
How is the price on that set?

Dave

 

[DKGrimm]

An alternative for me for melting aluminum is to use a small electric heat treat oven. I bought one years ago for other purposes so I thought it was worth a try. It's slow, but I live in a strictly residential neighborhood so it's nice to have no noise and no odors during the melt. A side benefit is that there is no hydrocarbon fuel burned so there is no source of hydrogen to gas up the molten aluminum, hence no need for degassing.

 

[timo_gross]

This one looks OK. What does everyone think for a beginner?

To me it looks O.K. on the one hand and suspicous on the other. The cruicible gripper ( do not know the english word ) looks as for very small equipment.
How much does it cost? Do they say how big the crucible is?


Here is what I used for some experiments. The coffee mug as size comparison.
Green 200 W blower also good to get BBQ going or use as cooling fan in summer. I guess all of it together was maybe 70 $US with the blower accounting for almost half of it and including the plumming for the DIY burner. The crucible was 12 $US or so it seems to be one size smaller than the one from the cylinder casting video. Long pliers made in India not expensive, must have for charging and moving hot things.
The Al slug was the left over from last melting experiment. A small LPG bottle was good enough to get half of the crucible liquid.
Burner is made following the built video i linked above. Burner works well enough and makes a good noise for the neighbour.

Long story short, my opinion: If the crucible from the set you showed is big enough for the parts you want to make incl. riser and feeder I would give it a try, provided they do not overcharge for the set.

Greetings Timo

p.s. should you get the set let us know how it turned out.

 

[DKGrimm]

Another suggestion: a local aluminum foundry sold me a big box of salvaged sprues and runners of A35 aluminum alloy for scrap price. Great for sand casting.

 

[dnalot]

I built my furnace from directions in the book "Gas Burners for Forgers, furnaces & Kilns" by Michael Porter. It has served me very well over the years and is still in great shape. The steel shell is made from a propane tank. I used two tanks so I could make it a bit taller. The refractory cement was store bought and that is why it has lasted so long. The torch is naturally asperated. I melt aluminum, brass and bronze. With a blower I can melt cast iron but that is pushing the limits of the furnace, so I tried it once and said never again. For bronze you will need a better quality glazed crucible if you want it to last. I can melt up to 10 pounds of aluminum.

Mark T

 

[darwenguy]

Hi tom, if you just want to keep it super simple for a first go you should be able to use your tourch, a pepper pot nozzle would help. For small amounts you can use a ceramic cup and a good hearth to keep some heat in.
I would highly recomend getting some oil bonded sand rather than greensand. It avoids a lot of problems i learnt as a beginer and gives a much nicer finish.
Good luck.

 

[Tom Watson]

Looks good
How is the price on that set?

Dave

A$299 + postage

 

[skyline1]

A side benefit is that there is no hydrocarbon fuel burned so there is no source of hydrogen to gas up the molten aluminum, hence no need for degassing.

Good point +1 for electric melting But I imagine it is rather more expensive and limited to fairly small furnaces due to the need for a pretty substantial power supply. And building an electric furnace is possibly not practical for most amateurs.

Gas porosity is a problem with home made Al castings We were lucky in that we were able to obtain small quantities of degassing tablets and active flux at very reasonable prices from Foseco foseco.org.uk Despite being a huge international company we found them really helpful and quite happy to supply our modest needs (minuscule by their standards).

Another REALLY helpful company was Purimachos of Bristol who make refractory materials of many kinds. When we inquired about refractory cements to build our little furnace they actually sent their Technical Director to see us ! It turned out this wasn't quite as amazing as we thought as he lived only a few hundred yards from us. He was so fascinated by our little "micro foundry" almost on his doorstep that he became a frequent visitor (and customer).

Having decided that they did not have exactly what we needed they custom made some specially for us and delivered it F.O.C. "for research"

Our heat source was a Sievert self blowing propane torch with a biggish nozzle on it which was simply directed through a hole in the side on the furnace.
this swirled up and around the crucible and worked really well. You should not point the flame directly at the crucible as it heats it unevenly and can even crack it

Minor rant coming !

Why are crucibles SO expensive, they are a major part of the cost in home foundrywork and have a limited life even if well looked after. (ours were positively pampered) They are made of similar stuff to pencil leads so it can't be the raw material and they are only simple moulded clay pots. !

O,K Rant over (I feel much better now)

I would highly recomend getting some oil bonded sand rather than greensand. It avoids a lot of problems i learnt as a beginer and gives a much nicer finish.

Yes, good stuff especially for a beginner you can even get it on EBay 20kg Petrobond Oil Bonded Metal Casting Sand for Gold Silver Delft Style Clay | eBay
It's a bit expensive compared to traditional green sand but it's pretty much ready to go. Green sand does require a lot of prep work and conditioning. It also needs a fair amount of skill and experience to get it just right.

Although traditional foundries are getting rarer and rarer all the time if you are lucky enough to live near one they will often sell you some if you can transport it.

Best Regards Mark

 

[Drawfiler]

When melting aluminium beware of iron, if the scrap includes screws etc or if you use an unlined steel melting pot, the iron can leech into the metal causing it to go very sluggish an impossible to work with.
A good source of metal scrap is old car engine pistons they are pretty iron free and actually are a special alloy to resist heat in service.