making ali castings

[taycat]

how hard is it to melt ali to make castings?
want to make some odd sized step pulleys for a little project.
would make a block then turn it down on lathe.
what equipment would i need?
biggest pulley would be 10" smallest 3".

 

[doubleboost]

how hard is it to melt ali to make castings?
want to make some odd sized step pulleys for a little project.
would make a block then turn it down on lathe.
what equipment would i need?
biggest pulley would be 10" smallest 3".

There is loads of information on the net
(A fair bit on my you tube)
Aluminium is easy to melt
A big propane torch & some fire bricks

 

[CRB]

The more work you put into the pattern, the less metal you will need and less subsequent machining.

 

[DanielW]

on you tube type in sandcasting aluminium

 

[Big Pete]

I've cast step pulleys, in fact they are the reason I got into it in the first place. They will need finish machining on a lathe, and they can be a pain to balance. I did mine a mostly solid, which is easier to make a pattern for, and is more tolerant of less than ideal sand. The additional mass also smooths out drive pulses, which may or may not be worth while for you. My setup is a 25l oil drum lined with refractory, and runs off propane and a hair dryer.

There's a bunch of pics of my setup and some castings here

http://s10.photobucket.com/user/Gar...3&page=1&_suid=142048411879604335661191409559

 

[Maker]

Back Yard Metal Casting, MyfordBoy and Doubleboost are the best resources out there.

 

[DAPPH]

I've cast step pulleys, in fact they are the reason I got into it in the first place. They will need finish machining on a lathe, and they can be a pain to balance. I did mine a mostly solid, which is easier to make a pattern for, and is more tolerant of less than ideal sand. The additional mass also smooths out drive pulses, which may or may not be worth while for you. My setup is a 25l oil drum lined with refractory, and runs off propane and a hair dryer.

There's a bunch of pics of my setup and some castings here

http://s10.photobucket.com/user/Gar...3&page=1&_suid=142048411879604335661191409559

Pete , where did you get the variable pressure propane regulator ?
Can you give me the specifications of yours please?
I'm kind of more than interested in getting another and starting off my metal melting again.

 

[Big Pete]

mine came in a box of stuff from a work clearout. It's actually a methane reg, but it works fine. Any adjustable propane reg that will do ~5-8psi should be fine, IIRC most welding outfits have them. My burner setup is as crude as can be, its a piece of exhaust pipe with a chunk of 1/4" stainless tube welded into it for a fuel injector. The hair dryer forces the air in so it doesn't need to be subtle.

This site is full of good info btw

http://www.alloyavenue.com/vb/forum.php

 

[brightspark]

just get and use a single stage acetylene burning regulator

 

[Turbo]

There's plenty of adjustable propane regs on fleabay. I bought one for my oxy-propane set-up for £1 plus £5 p&p! They are also called plugged regulators. You will need a lh thread fuel gas hose connector for it.

 

[DAPPH]

Thank you gents. I will start looking for them tonight.

 

[taycat]

I've cast step pulleys, in fact they are the reason I got into it in the first place. They will need finish machining on a lathe, and they can be a pain to balance. I did mine a mostly solid, which is easier to make a pattern for, and is more tolerant of less than ideal sand. The additional mass also smooths out drive pulses, which may or may not be worth while for you. My setup is a 25l oil drum lined with refractory, and runs off propane and a hair dryer.

There's a bunch of pics of my setup and some castings here

http://s10.photobucket.com/user/Gar...3&page=1&_suid=142048411879604335661191409559

i assume by solid you mean a round block?
that is what i was thinking off doing.
got massive bag of ali swarf from some bits dad did and stuff i have done was going to use that.
can i add drinks cans to mix?
will wash them and make sure dry before adding.

 

[Kent]

I found ali casting easy IF YOU LIKE VOIDS and UNEXPECTED changes under the visible surface. Why cast when you still need to machine and for parts that can be bought off the shelf or bought and adapted most likely. Not saying it cant be perfected at home but better to fight only the battles you have to fight and win them all

 

[bigegg]

Lost foam casting, is, IMO, the way to go - machine it first out of foam (the blue/pink building type, although white expanded polystyrene works), then cast it.

You can buy degassing salts (can't remember what salt, but easily available/cheap) which goes a long way towards stopping voids.
Add a bit (10%) of zinc makes for a better more consistent material - as does using cast scrap (such as alloy wheels) rather than aluminium extrusion scrap.

 

[bigegg]

Also, if you're casting swarf/small pieces, you need to double cast - melt the scrap, remove the dross, then cast into ingots.
when you remelt the ingots, it will be much cleaner/easier to cast.

 

[DAPPH]

I found ali casting easy IF YOU LIKE VOIDS and UNEXPECTED changes under the visible surface. Why cast when you still need to machine and for parts that can be bought off the shelf or bought and adapted most likely. Not saying it cant be perfected at home but better to fight only the battles you have to fight and win them all

The more you do in the long term the less difficulties you'll have , Big egg's comments about scum/dross removers & additives to make the metal flow easier are the secret along with the right temperature for the liquid metals of course. .

Most guys should be able to cast and machine a unique piece far cheaper than a unique or low production run die cast piece costs , plus there is the challenge and massive satisfaction when you get it right .

 

[Rocketman]

These pulleys sound quite basic surely just turning them up on a lathe from a solid bar/block would be far less hassle and time consuming and produce a far strong finished item to boot?

 

[bigegg]

These pulleys sound quite basic surely just turning them up on a lathe from a solid bar/block would be far less hassle and time consuming and produce a far strong finished item to boot?

possibly for a 2" single pulley, but if you're wanting a 6-4-2 step pulley (or whatever combination you like), that's a BIG chunk of bar to turn down for the smaller diameter - and VERY expensive to source ready made.
If it's done "lost foam", the pattern can be made on a drill press, and the cast pulley can be finished by hand - IF it needs it (usually cut off the sprue with a hacksaw, file smooth, then a quick sand)

I've made lost foam pulleys with extruded polystyrene where the shape of the little white balls are evident (which gives an idea of the level of detail which is possible) - I've done "lost wax" casting of a hand where the fingerprints can be seen.
Dipping the lost foam pattern in melted wax for a smooth surface, then a thin shell of plaster of paris before casting can produce a "finished" article (except for the sprues) straight from the sand.

S'pose it depends if you're a machinist or a founder?

 

[Rocketman]

possibly for a 2" single pulley, but if you're wanting a 6-4-2 step pulley (or whatever combination you like), that's a BIG chunk of bar to turn down for the smaller diameter - and VERY expensive to source ready made.
If it's done "lost foam", the pattern can be made on a drill press, and the cast pulley can be finished by hand - IF it needs it (usually cut off the sprue with a hacksaw, file smooth, then a quick sand)

I've made lost foam pulleys with extruded polystyrene where the shape of the little white balls are evident (which gives an idea of the level of detail which is possible) - I've done "lost wax" casting of a hand where the fingerprints can be seen.
Dipping the lost foam pattern in melted wax for a smooth surface, then a thin shell of plaster of paris before casting can produce a "finished" article (except for the sprues) straight from the sand.

S'pose it depends if you're a machinist or a founder?

Time wise I would have thought it would be way faster to do it on a lathe. So it really comes down to is your time cost free? The solid aluminium wouldn't cost that much but if you compare it to scrap ali yes it costs a lot more.

I suppose I'm looking at it with my business head on which may not really apply here.

 

[DAPPH]

Making the styrene form , coating it with a melted, shaped & scraped wax & then doing the plaster shell can make a much cleaner cast . Especially if you pour some petrol inside the styrene form after the plaster has set dried off ..it will melt the styrene into the petrol which can then be poured off . there will only be a thin innse wax shell which will melt /burn out as in lost wax casting & thus allow a much quicker mould filling so allow for plenty of decent sized sprues & vents .

Leave it for a few days to lose the explosiveness of the petrol , put it in the sand box copes /drags etc .then cast away , the finish will be as smooth as the outer shell of the wax was . You can also be artistic in the wax if it is thick enough & put your details , dates or " Stolen from .... etc etc. on it so it is cast in the cast item .