Clean your entire weld area well, 2 reasons.

[Gumby]

Clean your entire weld area well, 2 reasons.

Of course the first rule is you clean or shape the area for a proper weld.

But don’t rule out how an area around a weld can effect things.

Example, my oh so beloved 90* drill suddenly stopped last night.
Felt like something in the gear box broke. Once I got it open I found inside the sun gear was slipping inside of the case and the power never reached the chuck.
The sun gear has 3 notches on each side that locked into the gearbox case.
Which were magnesium and the 6 tiny tabs sheared off.

If you don’t know, magnesium is beyond flammable, like a blowtorch once going.
I took the case and made two punch marks in the area the sun gear was held, right down the seam of the case so it was easy to get on and off. I drilled two holes in the case for new notches to lock the sun gear.

Now I then welded two spots on the sun gear to line up with the new holes, weld a blob of metal to the sun gear in said spot and let that lock into the case so it can’t spin.

First weld went fine and then I shaped it for the hole, now the catchy part when I went to weld the other side I got a puff of smoke and fire, some stray grease was on the other side and was wicking up.
Which in turn hardened the weld to a point that I could not shape it with any of my metal files, I had to go get a metal girding disc to shape it.

30sec more on clean up would have save allot of trouble, and a few files.




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[ETsC10]

Great thread Gumby!
I especially like the re-enforcement of proper prep and the comment about Magnesium...it can be quite the hazard.

[Gumby]

The smell of sulfur when drilling it was quiet evident and helped clue me in.

It does say “magnesium used” for weight loss on the drill, but it was just on the metal covers or drop shields on each end, glad I didn't just drill the holes in the gear box then weld the notches assembled [would have done that if aluminum, no metal shaping] would have been one heck of a light show.

Other clue, the drill shavings felt like tin foil, not sharp at all like aluminum.

quick uboob search, magnesium rim in a fire
http://www.youtube.com/watch?v=IVuP4Nyw7MM

[ETsC10]

Magnesium can be pretty fun on camp fires. We used to add VW magnesium
during parties...man, those fires were bright!

I once witnessed a mag fire go through the chip tray of a lathe ...scary hot!

Back when I worked for Boeing, we were required to have a fire department rep
standing by until we were done working with the stuff.