lotus 30
classic car enthusiast mostly lotus
- Messages
- 684
- Location
- caldicot south wales uk
Great information thank you i may have a chance I'm i better getting a good tack then removing the top plate i have made as access with it on will be pretty impossibleFWIW a drop of vinegar is a more reliable test than trying to set fire to swarf, the acetic acid in it reacts instantly with mag and it's alloys (fizzing away producing hydrogen) but won't react with aluminium, even AlMg alloys. As said weight is usually the first big clue, corrosion the second... a bare mag casting that old would typically look a LOT mankier. Between the different flavours and tempers mag can sometimes be harder than ally, always machines waaaaaay more nicely though
I'd wager it's an AlSi?? casting simply as they're way more common. Probably AlSiMg given the age as i think AlSiCu is a more modern thing?
Personally i'd use 4043 filler wire and if it puts up a fight maybe switch to 4047* The various 5xxx series AlMg filler wires will usually physically work but can make life more difficult sometimes
* 4047 has more silicon in it and a lower melting temp because it's at the eutectic_composition Useful if what you're trying to weld is full of crud and/or when solidification cracking is an issue