Welding Tips and Tricks

Looking at amazing works shown on this forum decided to "fix" my own prop. It is about 30 years old Evinrude and had seen better days as you can see on the pictures. The motor exhaust is through the hub so there was enough oil and other s--t through the years of use.

"welded" at 200 Hz, 40\60 balance, 2% lanthanated, 120 A, 30 CFM, copper backing, 4043 filler, 6011 donor -11 Ga.
Everything was fitted, ground clean and prepped with acetone.
Long story short - I had a very hard time to establish a normal puddle and lay a bead. The alloy seems to be porous. Once it is heated enough it implodes and becomes a mushy peppery mess. It also often pops with a lot of soot. If I hold the arc long enough on one spot it produces a gray "cake" which is not melting at all. I had to stop, grind it clean and start over.
The 6011 donor plate with the same settings welds like a dream. Clean shiny puddle, full control, no soot.

So I cobbled together the prop as well as I was able to. Ground just to make it somewhat smooth and left it thicker at the bead hoping that it will be a bit stronger.

I would like to ask if there is a known "no-no" about welding aluminum props or I just stumbled upon a POS? Somehow people weld the cast aluminum low ends. I welded quite a bit of cast aluminum before but never had it that bad...

The lower units I have encountered seem to be pretty "clean" as far as cast goes. All the props that come in to our shop get sent out. Balance and pitch are your biggest concern with props. I'd suggest you keep it in the boat for a spare and buy a new prop to run. Sounds like you got your money out of the old one.

Kent

I run into that kind of mess when welding Muncie 4 speed transmission cases.

aeroplain wrote: I'd suggest you keep it in the boat for a spare and buy a new prop to run.

Kent, that's the plan... after I found that I cannot fix it well. On the other hand - how much longer the 30 years old motor can run. Is it worth to buy a new prop that will way outlast it? And I "sail" like an old granny, slow... Half a mile upstream, half a mile back to the landing.

big gear head wrote:I run into that kind of mess when welding Muncie 4 speed transmission cases.

lol Geeze I bet you do haha. I've never welded on them before simply because the cases are always shattered to pieces, but the castings have always looked horrid and very low quality.

Cricket, for what it's worth, I use these parameters, (75He/25Ar, at 120hz, 72-/28+ balance, at a 120 amps) and have really good results with most cast welds I do; however, it is possible that you could have just come up against a really bad casting as they seem sometimes to be the luck of the draw.

big gear head wrote:I run into that kind of mess when welding Muncie 4 speed transmission cases.

gotta love an old m22 rock crusher

As long as we busted the same prop once again last Weekend I welded it again. It does not have any value anymore so I played around and figured that my gas flow was too high for this particular cup. Once I dropped it to 12-13CFM everything became normal. Good clean puddle, quiet arc(except the AC buzz).
Thanks for the help!

P.S. A new prop is coming in two weeks but before that I will "test" the old prop hard.