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  1. #11
    Join Date
    Jul 2008
    Location
    Flin Flon & Creighton area
    Posts
    232

    Default I always try to put the ground right on the case.

    Quote Originally Posted by blackwire View Post
    Yeah I've played around on corroded cast aluminum,sure shows up some interesting things!lol!I was using a Precision Tig 225,but not enough power,welds good,harsh arc however.So I just ordered a Synchrowave 250dx,I tried an older one at work & liked it.Just as mentioned,the need to puddle fast on thick sections to lower overall heat input will be great.So far none (skegs) have fallen off leaving the dock..lol!Some that have been re-hit bent over & didn't break,happy about that.The biggest gearcase so far was a 150hp,but I didn't have to replace much.Ok I appreciate the advice & need one more opinion(for now).Where do you ground the welder on gearcase?Is there anything to the idea that current thru the bearings is bad?I was given two differing opinions around here
    Its usually best to ground as close to where your actually gonna weld, I try to usually put the clamp on the actual fin , that way there is much less chance of any arcing out of bearings etc. I know there are some that would not even think of welding without stripping the whole lower end, but if you are careful and develop a procedure for controlling the heat, its easy work. once you get your piece tacked on good you can maneuver the ground to get it out of the way of welding. I have had a couple where i had to tack a grounding tab of scrap aluminum very close to the edge of the actual weld joint zone, that way there are no random spots or arc strikes on the gear case.
    I have a welding addiction

    ...the only stupid question is the one you didn't ask

  2. #12
    Join Date
    Feb 2013
    Location
    N.W Ontario
    Posts
    10

    Default sounds good

    Thats a great idea about a ground tab.Grounding to the fin makes a lot of sense too,I am doing this now,but I've seen some guys ground to the prop shaft,handy but....My thoughts were getting juice from arc to ground away from bearings not thru them.Just one less thing to think about.A friend is a licensed marine mechanic and he says welding on empty gear cases is tricky -easy to oval the bearing bores.So I have been leaving grease in & taking my time to let cool down.It sounds like you have done a lot of aluminum work,I am enjoying learning how to weld the stuff.Do you ever weld skegs on with gearcase still attached to engine?

  3. #13
    Join Date
    Jul 2008
    Location
    Flin Flon & Creighton area
    Posts
    232

    Default done many still attached.

    I usually get guys bringing them to me right after they found rocks or reefs... I have done a lot with everything attached, the big thing is to not pound too much heat into the casing while you are welding, and also to control your interpass temperatures. I have a bunch of beach type towels i soak in water , and then place on the actual bearing bore area of the lower leg. you have to be careful with wet stuff and AC high frequency welding if you get my drift. Between passes i usually put another towel right on the weld area. This heat conducts out very fast so it doesn't take long to cool everything down quick. i occasionally use the IR thermometer to keep track off how hot, but i have done enough that touching them bare handed tells me how much welding a guy can get away with between "coolings" make sure you dry the metal off good before you start welding again also. the moisture hitting the molten aluminum puddle is neat to watch , but crappy to repair. Best usually to keep as cool as you can, no boiled out gear oil and rubber seals get cooked that way.
    I have a welding addiction

    ...the only stupid question is the one you didn't ask

  4. #14
    Join Date
    Jul 2008
    Location
    Flin Flon & Creighton area
    Posts
    232

    Default Oh yeah , and do not groud on the actual prop shaft!

    I just thought about your comment of what some guys do. I would never ground to the actual prop shaft. Aside from the bearings and the possibility of the bearing failing due to arcing out, the splined ends of the shaft can end up doing the same thing when fitted to their mating parts. a nice small gap of a couple thousandths of an inch between the high and lows of the splined parts could also cause similiar conditions. If one of the splines gets flash hardened it can become brittle and shatter . Usually this would cause the whole thing to pile up like a broken tooth on a gear, i saw a shaft that failed and this appeared to be the cause. you could actually see the temper colors on the shaft where the failure occured.
    I have a welding addiction

    ...the only stupid question is the one you didn't ask

  5. #15
    Join Date
    Feb 2013
    Location
    N.W Ontario
    Posts
    10

    Default gonna try it

    Great info -I can't wait to try this stuff...I always wondered why the gearcases were removed around here.Maybe I can save the boat owner some money doing it attached to motor.The damp towel idea is perfect.I'm glad I'm not the only one to be wary of HF shocks!I just finished an outboard test tank & got HF blasted(my fault) half inside the thing.Gotta be careful thats for sure.What kind of interpass temp we talking about?I need more experience to "just know",I have a IR temp gun too.Hopefully the 250dx will allow me to puddle faster & reduce heat soak.What welder are you using?

  6. #16
    Join Date
    Jul 2008
    Location
    Flin Flon & Creighton area
    Posts
    232

    Default you will learn if you have to remove them or not.

    I was always very careful when doing them while still attached, and havent had one of them come back saying i burnt oil seals or any heat warpage that oblonged the holes. I have a small synchrowave 180 sd in the garage and a trailblazer 302 with the hf251 setup. I usually just use the synchrowave and havent really been under-amped yet. I suppose it all depends on exactly how you prep your joint to put the skeg piece on. I usually tack it on really good and weld one side like a root pass then turn it over and grind the backside off to clean any possible inclusions or contamination and then weld the back side of the weld in a fill style pass. Then depending on how thick it has to be I will build it up alternating side to side to eliminate distortion and any real warpage. While i do this I use the wet towels to control the interpass temp and cool down the gear case as to not cook any seals or oil. It is a kinda tedious method but it has always worked for me and i have had no problems with defects in the welds , and the guy was always happy it was done right. I have found using the 4043 filler metal to be a little more forgiving than 5356, but i guess its all opinion. I use straight argon, but have tried and seen another guy use an argon helium mix that seems to really give more intense penetration, everything seemed to wet in better. I am a creature of old habits so I learned using argon and thats what i stuck with.
    I have a welding addiction

    ...the only stupid question is the one you didn't ask

  7. #17
    Join Date
    Feb 2013
    Location
    N.W Ontario
    Posts
    10

    Default Helium mix

    I have used the Helium mixes 75/25 & 50/50,they do work,but costly.The lighter mix is friendlier & does help reduce porosity.My Precision Tig225's arc transitions from soft (below about 150 amps) to a harsh digging square arc...good for clean aluminum.On thick cast sections it will agitate puddle LOTS.....with LOTS more crap pulled into puddle.So the Synchro 250 will help in that regard I hope.The one I tried was smoother-same arc across amp range.

  8. #18
    Join Date
    Feb 2013
    Location
    N.W Ontario
    Posts
    10

    Default Cast joints

    When welding cast aluminum joints have you found that square edge open roots pull more crap in?Like if there is no bevel on pieces to be welded?I tried this.....I imagine the cleaning action of arc was hampered or something....especially if the edge was rough(plasma cut).I guess thats why guys bevel!(lol).Like I said about the learning curve!The bevel also allows lower amps to be used.Do you let the puddle keyhole?I'm playing with this using copper back-up strip-pain the _ss & maybe not needed.

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