Welding Tips and Tricks

A friend of mine was over at the house the other day trying to patch up a few chips in a Seadoo prop with my Lincoln MP210 and was having a time. Couldn't get the arc to act right and didn't seem to want to burn the filler rod into the prop. My guess is that it was some kind of odd alloy of stainless. I think the filler was 309 or 316 and we cleaned it with scotch brite and acetone. It eventually worked out but it wasn't easy. Any ideas on why it did that or what kind of metal those props are made of?

jroark wrote:A friend of mine was over at the house the other day trying to patch up a few chips in a Seadoo prop with my Lincoln MP210 and was having a time. Couldn't get the arc to act right and didn't seem to want to burn the filler rod into the prop. My guess is that it was some kind of odd alloy of stainless. I think the filler was 309 or 316 and we cleaned it with scotch brite and acetone. It eventually worked out but it wasn't easy. Any ideas on why it did that or what kind of metal those props are made of?

I've welded on jet ski props using stainless filler, don't remember if it was 316 or 312/309 filler. I'd guess the issue was contamination. Was this a crack or a clean break you were trying to build up?

We were building up the edges of the blades where they had gotten thin and were chipped up because of rocks. We eventually got it but I wondered if it was anodized and that was what contaminated it?

Stainless isn't/can't be anodized

Contamination?
-welding in open air at prop edge, lack of shielding gas, mixing air into puddle,
no backup plate or purge gas damming, or solarflux backside coating
-mig welding with (presumably) 75AR25Co2 instead of 98/2 or tri-mix doesn't help
for corrosion protection
-TIG would be more appropriate

dave powelson wrote:Stainless isn't/can't be anodized

Contamination?
-TIG would be more appropriate

I didn't realize it was a MIG unit the OP referred to, I successfully welded with TIG and stainless filler, very low amps

LtBadd wrote:

dave powelson wrote:Stainless isn't/can't be anodized

Contamination?
-TIG would be more appropriate

I didn't realize it was a MIG unit the OP referred to, I successfully welded with TIG and stainless filler, very low amps[/quote

Whoops! maybe the OP did TIG it….he needs to chime in

We did tig it. Pure argon maybe 45 amps. Gas was on 15-20 cfh inside my building. We didn't use a backing plate though. That may have helped but not sure. Didn't know if maybe Seadoo put something on their props. Not anodized but some kind of coating?

jroark wrote:We did tig it. Pure argon maybe 45 amps. Gas was on 15-20 cfh inside my building. We didn't use a backing plate though. That may have helped but not sure. Didn't know if maybe Seadoo put something on their props. Not anodized but some kind of coating?

You have to think though, if you're welding on the edge, you're creating a low pressure zone right on the back side of the prop as the argon blows by. Kind of like lift on a plane wing, it will pull air in with the venturi, contaminating the weld.

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I had some aluminum I could've used to back it. Thanks for the explanation of what could've been happening. I'm sure we'll run into this again so next time I'll try to back it.