DIY Aluminium Casting - Anyone done it?

[georgexs]

I've been thinking about casting my own manifolds for supercharging my MX5, does anyone have any experience with making a DIY furnace and doing some casting with aluminium?

There are already manifolds for putting an Eaton M45 which I have (MINI Cooper S flavour) onto an MX5 but (a) I think they look curse word (and must flow curse word as well) and (b) I like a challenge.

My plan is to do some investment casting, but instead of using a wax mould, use a 3d printed plastic mould.

I bought a 3d printer earlier this year and I figure this could be the perfect project for it as I can make a really nice flowing manifold very easily using it.

Essentially copying this idea with a more complex mould: 3dtopo.com/lostPLA/

Anyone attempted anything like it before?

[SamR380]

That process looks good in theory but bear in mind the size of the things he was casting, compared to an inlet manifold!

DIY furnaces are quite common for making jewelry (using old gas bottles as a base) but again that's all pretty small stuff.

I'd love to see it done but you're going to need a pretty big furnace... good luck!

[georgexs]

Ah should have said, not going to aim for a full big inlet manifold, that may be a bit ambitious!

Most people mount the chargers on the hot side of the bay for easy packaging so have seperate inlet and outlet manifolds for the supercharger, as the MINI casing has some unusual shaped casting to mate onto.

Inlet (flows in from left):


Outlet (flows out towards the camera and then left):


So I'm going to try and make my equivalents to these two.

[3point141]

if you are investment casting... here's how you get the plastic pattern out of the refractory mould;
normally, a wax-pattern is melted out by; firstly placing into an autoclave to melt out the bulk of the wax before being transferred to a kiln for firing (800-degrees for 12-hours)

With this in mind. I'd suggest simple parts can be made by the more basic sand casting method. there are plenty of sources of information should you decide to follow this route but you will be limited to far more simple part geometry, unless you make some very complex multi-core patterns.. which is very tricky.

OR you could make a sacrificial pattern (3-D printed out of a lower-temperature melting polymer should be acceptable) and actually get a proper company to make it by the lost-pattern route. Seriously, I'd forget the idea of investment casting at home, the process is nothing like sand casting, which in itself is already pretty hard for the DIY foundry-man.

I can recommend this place for low-volume casting work; based in sheffield
www.geallencastings.co.uk/

I used to work there

[v8ian]

Home casting is full of pitfalls, ranging from the type of sand you use, its purity, this can cause porosity, the type of aluminium is not always suitable for home casting, especially ones with a lot of zinc in them, which can burn off and give highly toxic fumes, magnesium in casting alloys can make them flammable, normally controlled by dusting the surface of the pot flowers of sulphur, not a pleasant substance when burning either.
One of the biggest dangers of casting is moisture on the mould, think how hot oil reacts when water is introduced, have a moist mould, and the metal has the potential to explode out of the mould and causing serious harm.
The foundry where I did my apprenticeship, in the 50s took the roof off its main building when a large box exploded, 2 fatalities and several bad injuries,

[colnerov]

Hi, the thing with forced induction is that it doesn't have to be flowed because the air is being...well forced through.

Colin

[SamR380]

Air still flows, just at higher than atmospheric pressure. Works the same as 'system head' in hydraulics: less restriction, more fluid (air) moved for the same pumping effort. In car terms, better flow = increased power from the same size turbo/supercharger.

[georgexs]

Jul 21, 2015 11:58:04 GMT 3point141 said:

if you are investment casting... here's how you get the plastic pattern out of the refractory mould;
normally, a wax-pattern is melted out by; firstly placing into an autoclave to melt out the bulk of the wax before being transferred to a kiln for firing (800-degrees for 12-hours)

With this in mind. I'd suggest simple parts can be made by the more basic sand casting method. there are plenty of sources of information should you decide to follow this route but you will be limited to far more simple part geometry, unless you make some very complex multi-core patterns.. which is very tricky.

OR you could make a sacrificial pattern (3-D printed out of a lower-temperature melting polymer should be acceptable) and actually get a proper company to make it by the lost-pattern route. Seriously, I'd forget the idea of investment casting at home, the process is nothing like sand casting, which in itself is already pretty hard for the DIY foundry-man.

I can recommend this place for low-volume casting work; based in sheffield
www.geallencastings.co.uk/

I used to work there

Yeah the shape of manifold i'm thinking of would be difficult to sand cast, would need several cores, for that reason I think it'd be too difficult for me to attempt doing DIY. 

I was leaning for the sacrificial pattern, you can now get some 3d printing polymers specifically designed for this application, turn very thin and wax like when they are heated to about 270 IIRC.

Thanks for the advice, I'd already approached one company about doing it and they were very dismissive of it, said they'd tried it before and the plastic had expanded and cracked the mould. TBH they weren't interested in doing low volume work anyway though. Thanks for the suggestion, i'll get in contact with them.

Jul 21, 2015 20:23:52 GMT v8ian said:

Home casting is full of pitfalls, ranging from the type of sand you use, its purity, this can cause porosity, the type of aluminium is not always suitable for home casting, especially ones with a lot of zinc in them, which can burn off and give highly toxic fumes, magnesium in casting alloys can make them flammable, normally controlled by dusting the surface of the pot flowers of sulphur, not a pleasant substance when burning either.
One of the biggest dangers of casting is moisture on the mould, think how hot oil reacts when water is introduced, have a moist mould, and the metal has the potential to explode out of the mould and causing serious harm.
The foundry where I did my apprenticeship, in the 50s took the roof off its main building when a large box exploded, 2 fatalities and several bad injuries,

That's interesting, when I was at school we used to sand cast stuff quite regularly, I remember it being quite easy, we were well kitted out for it however.

The aluminium I plan on using is from Bosch Rexroth extrusions which we have in plentiful supply at work going spare. A bit of digging reveals it's 6063t6 alloy, which is rather nice stuff, low zinc content too.

Thanks for the advice, i'm not going to walk into doing this blind, i'll be doing my homework.


Another avenue I'd thought of (and this may be curse word) was to cast a manifold using high temp epoxy resin. Far less fraught with danger, but I don't know if it'll work!

The resin says it's stable up to 180 degrees: www.easycomposites.co.uk/products/epoxy-resin/very-high-temperature-epoxy-laminating-resin.aspx

Which should be enough, from what i've read most people see supercharger outlet temps of around 110 max, although I need to run the theoretical numbers myself to be sure, found the supercharger data curves so that should be easy enough. I could also impregnate the epoxy resin with aluminium powder to make it look like a ally manifold.

[georgexs]

Jul 21, 2015 20:59:55 GMT colnerov said:

Hi, the thing with forced induction is that it doesn't have to be flowed because the air is being...well forced through.

Colin

Jul 21, 2015 21:37:00 GMT SamR380 said:

Air still flows, just at higher than atmospheric pressure. Works the same as 'system head' in hydraulics: less restriction, more fluid (air) moved for the same pumping effort. In car terms, better flow = increased power from the same size turbo/supercharger.

As SamR380 says less restriction is still the aim. 

The kit that exists already for putting the MINI charger in an MX5 takes this nice charger inlet shape:

and ruins any good flow into it by turning it straight into a round pipe (bottom left):

[slater]

No it doesnt. don't forget the air is moving from the pipe into the blower.

[skylinedave]

I really would not bother with casting . If you are doing it at home are you really going to be able to provide enough heat to melt all the aluminium you need, and get it poured all in one quickly ? And the cost of building moulds , one or two oxy sets of burner made .

I would just pay someone to fabricate something , if its two tight for a bend or piece of a good company should be able to use parts of pressings .

[logicaluk]

Home made furnace





Dan

[edwell]

I have been looking into almost the exact same thing except for a set of inlet manifolds for some ITBs on my 205. I think home casting is fairly common although not without its "health and safety" risks. There seems to be plenty of info out there on making the furnaces etc, and products like moldlay make the transition from printed part to casting mould a lot easier. Like you I did some sand casting at school and it seemed dead easy at the time, maybe ask your local school or college if they would be interested in helping for a small donation to the school fund?

I am going to try using a printed part as the final piece. A lot of intake manifolds are plastic nowadays, usually nylon, my printer can print nylon, It is petrol proof and doesn't melt under 200 degrees and I guess they will be quite well cooled with air constantly flowing through them anyway. What is the worst that can happen? (apart from a catastrophic engine fire etc!). Your supercharger manifold might be a bit too structural for plastic though and boosted air will be hotter etc.

How about cold casting in some form of resin? you could 3D print the mould (as opposed to a buck?) and reinforce the piece with fibreglass of similar. Will the injectors be after the printed part? If so then you wont have to worry about chemical resistance, just temperature range and strength.

[skylinedave]

Why not just get a 3d part made and send that to a foundry ? Saves a big chuck of time and or money .

[chairchild]

Done lots of research into backyard metal casting - even built a couple of furnaces (but had nowhere to actually light them alas). The bits I can recall, that will be of use simmer down to:

The right aluminium is a major part. Using extruded aluminium is actually going to make your life harder, as it doesn't have enough silicone content to flow nicely when molten. The best source, is something like engine cylinder heads. These can be cut down into manageable sized chunks, and will still have enough of the "right" chemicals once you've had it smelted in a non-industrial furnace.

Degas your molten ally - some say to only do it once it's been melted a few times (ie: from engine parts, into ingots, then remelted to cast something else) but the general gist I took from it, was just do it every time. One method involves dropping something in (which for the life of me, I can't remember what it is) another involves bubbling pure Argon gas into the mix.


For the furnace, use a crucible of a decent thickness of steel - I had an old CO2 tank that I chopped in half, and welded stubs to the top to lift+tilt it with. Once you've made it, leave it outside to go as rusty as possible - molten ally will barely react with it (compared to clean steel, or stainless steel). If you're thinking small-scale, a disposable welding bottle would work well. Charcoal + a big fan is a good cheap way of getting the heat you need. And if you want a speedy warmup, insulation of the furnace is not to be snubbed at!

With your pattern - sprues, and risers, can NEVER be too big! Most of your ally will go into filling these. Styrofoam works well for these basic parts (and even for the main parts!) and burns straight out if you pour ally onto them.


For the actual mould, a light coating of plaster of paris, then supported in a bucket of dry sand (any sand will do tbh). The plaster will breathe just enough to allow vapours/etc to escape into the sand, whilst supporting the shape. The sand also plays a big part in supporting your structure. Having a high "head" pressure into the mould (a long runner) can help with intricate shapes.





However......


Whilst it's pretty fun to make moulds, and furnaces - fabricated parts from steel are MUCH easier to make, and cheaper too.

[waveman1500]

myfordboy on YouTube is the best channel I have found for DIY casting. This man is extremely dedicated! Well over 60 videos with a lot of detail.

www.youtube.com/channel/UCNC9gjgYrzLfyMQmp31DnjA

It looks expensive and time consuming. If you use propane as your fuel, you will use a lot of it. You can use old engine oil, but it requires a special burner with a supply of compressed air to spray it in using a venturi. Basically, it can be done, but don't expect your first few parts to turn out right. I've never done it personally, but often thought about it!