Welding Tips and Tricks

How can you tell aluminum from pot metal? Tried to TIG a lawn mower engine case with shitty results. Does pot metal TIG? Any suggestions?

I doubt if the engine case is pot metal. It is probably cast aluminum and if it's old it is probably permeated with oil and carbon. Need more info on your results from the first time to give more advice.

If you take a file to it, aluminum will be soft, gummy, and shave off easily, while Zinc-laden aluminum (pot metal) will be harder, and resist the file more so you'll have to press down harder to get the file to shave anything off.

In my experience with cast aluminiums, cleaning is key. Since you are welding a engine(remember that metals are porous and as such absorb contaminents, meaning non-metal) the aluminium will be laden with all sorts of contamination. I recommend using some sort of grinder-operated wire wheel to start, and running a lit tungsten over the weld area( the ac current will help clean it). Another trick is to make a weld, grind it flat, and make another weld, and contenue to do this until the weld looks clean and non-sooty(you may have to do this more then once), and the arc becomes stable over the weld area.

also, play around with different rod types, I have only ever used 4043, and I make it work becuase I have to, but something tells me someone out there makes a rod especially for dirty aluminium castings.

The owner of this site once recomended torch brazing to me for a similer problem. I dont know.

Hi, not got any experience (yet) but that welding rod you need might be

Hastelloy W

Do a search on here, the man who knows said something about it.

HTH

johnny

steam it!...there is a "pot metal" rod ,its got a square profile like lead rods and cast iron rods...we have a local supplier ... www.joneswelding.com they are here in the southeastern u.s. -tallahassee -thomasville-albany-cordele

johnnywgk wrote:Hi, not got any experience (yet) but that welding rod you need might be

Hastelloy W

Do a search on here, the man who knows said something about it.

HTH

johnny

Nope, dont try hastelloy W...it only works on steel and nickel alloys...a good aluminum rod for castings is 4047

jody

Been doing outboard motor blocks for awhile now. Jody's dead on with the 4047. Here's the trick I use. Clean the part with Dawn dishswashing detergent and warm water. Clean again with Acetone. Heat to 200-250 to bring the soaked in oil to the surface. Wait until it cools in natural ventalation. Wire brush and Clean with Acetone. Wash and Rinse with Dawn again then scrub the part with de-ionized water until the water forms a solid sheet over the area to be welded. Some times I have to repeat the process a couple of times.

If you have a blast cabinet (I do) then you can blast it with 60-70g crushed glass after the first detergent wash. This will open up the pores of the metal and helps to release the contaminants during the heat process. DO NOT GLASS BEAD it will close the pores and the heat process won't draw the contaminents to the surface.

Pretty much, this is the same cleaning process you use when you use Alodine 1201 as a surface conversion/paint prep. Make no mistake, it's a lot of work but the end result is worth it.

I ran across a material yesterday that was curious - the crankcase cover of a honda motorcycle. Does anyone know what kind of alloy this might be?

It appeared fairly brittle, as it had fractured into several small pieces from an impact (which I was asked to repair) with very little bending of the material involved. The file test told me that the material wasn't much different than common aluminum alloys. (It was certainly a lot softer in comparison to my zinc-aluminum filler rod.)

In a "weldability" test I made with the TIG torch (on one of the fractured pieces), it appeared that the alloy had a significantly lower temperature melting point than standard aluminum alloys (as I could jab my 4043 filler rod into the puddle, without it necessarily melting the 4043.) But adding enough heat to melt the 4043 resulted in it flowing together nicely, with no hot cracking noted.

The material also exhibited no "zinc burning" tendencies. To be sure I was getting it hot enough for zinc burning, I tried dabbing in some zinc-aluminum filler rod, and then sure enough the zinc in that stuff burnt and smoked quite readily.

I wish I had some 4047 to use to weld it so I don't need to add so much heat, but I guess I'll just use 4043 and hope the heat doesn't runaway on me. The thickness of the part is mostly in the range of 1/8"-3/16".

Update - the motorcycle crankcase cover seemed to not be pot metal after all. I had no issues with it melting excessively while welding it.