Sand casting in our workshop!

[pasner]

Dear all,

We would like to sand-cast a reed valve manifold in our little workshop, try at least, but we don't know the aluminium alloy to be used in these kind of parts.

Anyone can advise us on this?

We know that Al-Si are the most common ones, the A356 and A357 alloys. Any idea what kind of aluminium is used to produce this lammy part? Any advice and idea wellcome.


Best regards,

[willwander]

I'd love to have a go at casting, there's quite a bit of info on the web about it, including the various grades of ally etc

Can't you just melt down an old one? or have I been watching too much 'Worlds Fastest Indian'

[warts]

Like the man said, melt down some old stuff, piston alloy is quite hi tech, but would definately have the mechanical properties necessary. "straight" aluminium would have the lowest melting point, the more alloying elements generally the higher the temperature required. Beware of appling too much heat to these, as its possible to "burn off" or change the mechanical nature of the alloy.
For a manifold, I would think any low tech stuff would do. You can buy ingots of most al.alloys, which means at least you know what you're starting with. I would always use some degassing tabs to reduce the chance of porosity- which you would get from the same place.
To make your pattern, for something like a manifold, you could try using your old one built up with body filler to give you something close your design, then file/grind off to achieve the exact shape you want.
Once you have made your mould, the gating is usually the next problem to face. But I guess the websites tell you about that.
Major probelms WILL be caused by pouring molten metal into anything with moisture in!
Take care, have fun

[RICSPEED]

lost wax is a good way but you will need to make a wax replica of the part you want to cast

[willwander]

a good scrap bin is never empted

[RICSPEED]

true ...cant remember where i posted that ...i guess there wise words that made an impression

[Rich_T]

You could try plaster patterns, I've done that before but you really have to dry them out over a couple of weeks or they tend to spit and crack. I sculpted positive shapes from body filler and old parts then made plaster moulds (good for 6 castings or so).

Making the core and print out is a little more involved but you get the basic idea. If you start to chuck a couple of 100 quid at it you might as well make a cheap CNC tool.

[willwander]

... If you start to chuck a couple of 100 quid at it you might as well make a cheap CNC tool.

I would have thought cnc would be better...but not as much fun

[DMC]

As warts says, degassing tablets are a must especially if your using old scrap. I used flux as well, a couple of table spoons on top of the melted ally.

This may be of interest to you, I'll leave it on to the weekend.

https://docs.google.com/viewer?a=v&pid= ... y&hl=en_GB

[coaster]

As warts says, degassing tablets are a must especially if your using old scrap. I used flux as well, a couple of table spoons on top of the melted ally.

This may be of interest to you, I'll leave it on to the weekend.

https://docs.google.com/viewer?a=v&pid= ... y&hl=en_GB

Wow, that takes me back, we used to have to do sand casting as part of the O'level metal work carriculum at my seconbdary modern school. I made a compulsory set of screwdrivers (had to forge the blades) and then cast the ally handles on them. I then made a deck cleat for a sailing dinghy using a wooden former made during woodwork