Not strictly welding but...

[jeremyf]

I know its not welding but you guys know all things metal...

I have a brass drain plug in an alloy case which is seized/very tight. Possibly not moved in 10's of years. I was considering using heat (I have propane or mapp gas torch) but was worried about melting the case. Is there an indicator material/putty that I can stick on the case which will melt at a certain temp eg 200 degrees?

Any advice on getting this plug out - its a flat screwdriver head and I have air impact wrench or hammer impact driver but I think the head will get mangled with too much force? I just want to drian the oil and refill and not dismantle the gearbox. (Its a small rotovator gearbox)

thanks

Jeremy

 

[rtbcomp]

You could use a bit of thick oil and stop heating when it's boiled away. Keep the flame moving.

 

[wyn]

You can buy things like "tempil sticks" that give an indication of when you reach a certain temperature.

If you rub soap on an aluminium surface it will turn black when it gets to the annealing temperature. which i think is around 300-400*c.

I should imagine the screw driver slot could well get chewed up before the plug comes out. You could drill it out and try to remove whatever is left but if it is an old machine it might be tricky getting hold of another drain plug.

Maybe even drill and tap the casing somewhere else to fit another drain plug.


If the machine is only small you could turn it upside down and drain the oil out of the filler hole or any other bolt hole it might come out off. The trouble is that would spread the accumulated gunge back around the box.

 

[hotrodder]

Wouldn't worry about melting the casing with MAPP/air, a decent sized chunk of ally conducts the heat away faster than a small plumbers torch can apply it. Go with MAPP as the faster you can heat it the better luck you'll have.

I'd go with the bar of soap (or a permanent marker- ink will burn off at similar temp to the soap turner black) as a temp indicator, mark in several places adajcant to where you're heating but you'll probably get bored before you reach annealing temp of the casting with a small plumbers torch unless the gearbox casting is sub 2mm ish wall thickness

 

[jeremyf]

Ok, thanks for the replies. I'll give the MAPP a go and report back. Once heated up, should I try and cool the brass with a metal object to shrink it or something

jeremy

 

[hotrodder]

Won't hurt anything, could use compressed air too. Ally has a slightly rate of expansion than brass IIRC which'll be in your favour in breaking the 'seal'.