Casting grain

[Julian]

I was looking at cooksons 925 casting grain it says : "Casting Temperature Range : 970 - 1090°C. Nominal Cast Hardness HV : 75 Flask temperatures are typically 500-600°C "

Solder melts in the 700 - 750 range. Does this mean it can't be soldered?

Julian

[Dennis]

No it can be soldered alright, even with hard solder. The only problem is that castings blot up solders, so you have to be canny how you do it.

Normally what you want to add on is sheet or wire, and they have to be liberally coated in solder and then sweated onto the casting to give a secure joint.. Dennis.

[Julian]

Ok thanks, but what do they mean by "Flask temperatures" them ?

Julian

[ps_bond]

That's the temperature the investment should be at to avoid chilling the metal too quickly. The flask is just what holds it - and in a pinch, can be a tin can with the ends cut off (although offcuts of stainless exhaust are a better solution on the cheap end).