Ok So how do i decide how much to melt.

[trapper]

Im in the process of building my own refactory furnace with the intention of using it to cast in alluminium brass and bronze. I'm at the stage of collecting all the bits to start the build . In the meanwhile I'm doing my best to learn the how toos.
One question icant get to grips with is how much do i need to melt for a given project is there some sort of weight to volume calculation. my greatest fear is not melting enough for a required pour

 

[hermetic]

Try this formula,

The approximate weight of a casting can be determined by weighing the wood pattern and multiplying by the appropriate factor indicated. Aluminum 8, cast iron 16.7, copper 19.8, brass 19.0, steel 17.0.

A white pine pattern weighing 1 lb, when cast in aluminum will weigh 8 pounds, in brass 19 pounds etc.

from http://ze-engineer.blogspot.co.uk/2010/02/metal-casting-pattern.html
Hope this helps,
Phil.

 

[jpfabricator]

A more hands on approch, and a more exact mesure, would be to measure the volume of the pattern. If it will fit in side a 5 gallon bucket, fill the bucket with water and the pattern till it is completly coverd. mark the water level, then remove the pattern, letting the most water run back into the bucket. measure the diffrence in the water level, then multiply that by the radius of the bucket, multiply that by pie (3.14), then all that by the radius of the bucket again. This will give you the cubic measurement of your pattern.

Since I use the english standard it would look like this,

water level diffrence in bucket X radius of bucket X 3.14(pi) X radius of bucket = in/3

Then you can do the same for a one pound piece of aluminum, wich would give you the cubic measure of 1# of aluminum.

 

[trapper]

Try this formula,

The approximate weight of a casting can be determined by weighing the wood pattern and multiplying by the appropriate factor indicated. Aluminum 8, cast iron 16.7, copper 19.8, brass 19.0, steel 17.0.

A white pine pattern weighing 1 lb, when cast in aluminum will weigh 8 pounds, in brass 19 pounds etc.

from http://ze-engineer.blogspot.co.uk/2010/02/metal-casting-pattern.html
Hope this helps,
Phil.

Thanks Phil
I'm guessing but common sense tells me to add a bit so to achieve for example an 8pond aluminium cast I should melt maybe 9lbs etc
Its some time off before i actually get casting although im making up the wooden patterns
Thanks again
Steve

 

[trapper]

Thanks for that between the two approaches I'm hoping I can build up a data sheet which should help in stock control as much as in casting actual items by allowing me to size some casting ingots as well .

 

[DMS]

Don't forget to throw in a bit extra to account for dross, and the material that will take up the gates, sprue, and riser.

 

[Hawkeye]

Once you're close to the required amount of metal, I'd suggest add in 20% or so. That accounts for dross, as DMS suggests, but also for any factors missed in the first calculations. Any extra can be poured into muffin tins (not the good ones) to make convenient ingots for the next melt. That also tends to clean your metal so that there's less dross next time.

 

[Snag_one]

I usually melt about 1.5X what I think I'll need for a given casting . This will allow plenty for risers and sprues , and any leftover gets cast into ingots . Here's a photo of the flask pieces I cast , before machining . Apologies for the large file size , I didn't realize these hadn't been resized ...