Welding transmission housings

The materail is mild steel plate that I bead blasted. Gas is argon. We could hear the gas coming out of the torch, and he said he could feel it when he stepped on the pedal.

I have practiced with no filler rod and it looked a lot better than last night. Actually for the last two times in class it went downhill. And with the woman instructor more interested in chatting I just kept practicing by myself. Last night the reason Nathan came over was I said something to the admin lady. Told her I think it would be a good idea for the instructor to check in with every student at least once per class.


This was my best weld other than the crater at the end. Looks more like wire feed than tig. This was my second night at class. Same materail, same bead blast surface prep.

Then everything went to crap.
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Before you move up to ali welding get the mild steel nailed down. I have been having success with fairly simple ali box section fabrications.

But half the time I try something more complicated or more mass/thicker material I have the sudden "where did it go?" moment as the aluminum gives no obvious warnings that it's about to burn through.

By the way the beads are looking ok , it's just about practice and learning the dexterity. The finesse comes with time.

I've been using someones button torch recently which has taken a while to get the hang of as I'm used to a foot peddle.

:)

Stu
 
Welding cast ali is trying at the best of times. Dubious quality ali, porosity, baked in oil, inclusions.... It's not pretty. A spool gun may goober some metal on there, but you're fighting the same things with far less control than with the TIG torch and no reverse arc cleaning action and no ability to let the arc longer and let the impurities pool out. A good recipe for having some metal snot sat on top, but not bonded to the casting. The low temp soldering rods have a slim chance of working, but you'll fight oil and inclusions bubbling out too. Take a torch to it and see how much smoke you get coming off it as it heats...

The various problems illustrated perfectly here:


I'm a great believer in the mantra "make your requirements less dumb". Meaning absolutely no disrespect. It's easy to tunnel yourself down one particular way of thinking and totally miss a smarter way. The best solution here involves not welding it if at all possible? Even if that means different positioning. Or could you mill a flat and a piece that bolts on and seals with a gasket?
 
It's a pretty steep climb to go from zero to welding used, oil impregnated cast aluminum. Once you feel like you've finally got a handle on steel, you start all over again on aluminum. I would recommend getting some pieces of a scrap trans housing and going to spend a day or two with your weldor friend. Take plenty of his favorite beverage.
 
Based on your reported location, I would suggest looking for someone that repairs damaged chainsaw crankcases. It is a very similar job, welding on stressed diecast aluminum parts that have been immersed in oil. Usually, these welders do jobs for auto enthusiasts, too, and will understand what you are trying to do. Years ago we had a guy in this area who could weld up a crankcase with a hole in it from a thrown connecting rod, so with the advances in technology, your project should be very simple for someone with that sort of experience.

Ask around at the local saw shop. You should have a name and phone number within a day or so. Often, the pay is with beer! You get to chat and help drink the beer, and perhaps have found a mentor.
 
Your TIG class sounds as bad as my first one. The instructor gave us a 1 hour lecture with notes, then lined us up behind the welding bench. We were allowed to weld until we dipped the tungsten or burned through. I managed to weld about half an inch before I failed (first time). This kind of reminded me of PE class when I was a kid. 90% of the students fell through the cracks and received almost no benefit from the class.

I hate to say this, but it is not safe to do nearly anything these days without a review. Youtube can really help. Everybody tells me that I should go to community college and take a course. Maybe this was once a good idea, but all the welding programs have been shut down. The closest one is in Aptos, which isn't really in the Bay Area. Over an hour under the best of conditions. I know some of the staff who worked there a few years ago. They are really serious and devoted teachers, but they said that the students often lacked basic learning skills, and most of them never made anything of this resource.

Going back to my course, I don't blame the teacher. He was a good blacksmith, a better CNC machinist, and an amazing foundryman. Maybe welding was just not his thing. I think that, looking at his website discussing his views on education, that he expected the students to catch the spark from their few minutes of hood time and buy their own cheap import TIG welder and watch Youtube or barter their way into a decent lesson. It worked for me. Try to find somebody to help you. That class sounds terrible.

As for those TIG welds, you should be doing better by now. I suspect bad gas or a leaky torch. Quickly find somebody who can show you the right thing.
 
alloy said:
I guess I should have chosen a different word other than boring. Where the sleeve has to go only half the sleeve is surrounded by the tail housing casting. The other has is out in the open.

I'm not at my shop now, but I'll post pics later. Ironically I'm in town waiting to go to my welding class. I came in early yo get my 2nd covid booster.

Yes they stressed metal prep in my class. And the housing is saturated with oil for the last 20 years.

I've looked at the map gas cylinders. Can I use them on my propane torch head?
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Yes you can, and it burns hotter.
 
I'm still not real good at TIG welding but when I first started I found it easer to use a finger controll/switch and just set the amps. Another thing I learned is that with TIG welding things need to be clean. Not only removing the mill scale but wiping the metal down with acetone after bead blasting also helps. Sometimes I leave my filler rod just laying next to the welder, if it's been a day or two I wipe it down with acetone also.
 
alloy said:
Top plate is all me except for the one weld the bottom two rows. Second plate is all Nathan. I gave up and left before the class was over. I don't understand why everything turned brown.


alloy said:
Top plate is all me except for the one weld the bottom two rows. Second plate is all Nathan. I gave up and left before the class was over. I don't understand why everything turned brown.
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You have a couple of possibilities here, but let me back up just a touch. With problems like this you need to remove variables as much as possible.

TIG needs everything clean...no coatings, no contaminants, no oil, etc. In the top plate you didn't do any surface prep like in the second plate where the use of a grinding wheel shows. Even "clean" metal needs to be taken to white, shiny metal, and then ideally wiped with acetone. Even a grinding wheel can leave behind traces of the wheel that will cause issues. Often you have to use a grinding wheel to remove mill scale, then a flap disc to get to smooth, shiny metal, then wipe with acetone. If it's really important I follow the flap disc with a unitized wheel which is a non-woven abrasive similar to compressed Scotchbrite. In short....clean, clean, clean!

Once you've got a clean surface you can look at other stuff. It certainly appears to be a gas issue. It could be the wrong gas (needs to be 100% argon). It could be contaminated gas (it really does happen). It could be a leak somewhere between the tank and the torch that's pulling in oxygen. Aside a normal check for leaks, the easiest thing to do is try the bottle from another machine that's working properly.

Once you've done that, confirm you're getting flow out of the torch. You want to set the flow meter to give you double the cup size being used in CFH on the flow meter. So, if you're using a #7 cup on the torch, shoot for around 15CFH on the flow meter.

As far as machine settings it's not too critical on steel...as long as it's DC electrode negative. What model welder are you using?
 
On the question of the transmission housings, realize that aluminum is quite different from steel/stainless. People on welding forums will debate whether aluminum is "harder" to weld than steel, but that's a welding forum...they argue over almost everything...lol.

In general, aluminum is more challenging for most people to get the hang of. Assuming the casting can be welded (some aluminum castings are nearly impossible to weld) you have to approach it differently. The oxide coating on aluminum melts at around 3800*F while the aluminum melts around 1200*F. Because of that, you have to hit it hard with lots of heat to get through the oxide, then back off quickly so you don't blast through the base metal. Because aluminum transfers heat so efficiently you can't just creep up on it like you can with steel by gradually applying the heat. If you do that, you'll put so much heat into the metal the beads won't cool and freeze properly and you'll have to move very quickly to try keeping up with the heat...usually you get frosty, ugly beads or blow through the metal the farther you go.

The short version on proper technique for aluminum is that you want essentially full throttle so that you get a puddle started in 1-2 seconds, then back off and start adding filler. Because of that heat transfer you also have to move fast with the torch and filler. Dab, move, dab, move, dab move...very little in the way of pausing. That often means people struggle most with feeding wire fast enough with the support hand. If it starts to get away from you it's just better to stop, get reset and start again.

The heat transfer and oxide issues also mean you generally need a machine with more power for any given thickness compared to steel. For example, my small TIG is a 210A machine and the practical limit is around 3/8" thick aluminum. Yes, you can stretch it by using lots of pre-heat or adding helium to the argon (even 20% helium helps a lot, but it's very expensive). When I weld 1/8" coupons I normally set the machine around 150A and use most or all of that to get the puddle started...just as a point of reference.

If you're around water with marinas you might be able to find someone who repairs outboard motor lower units...usually cast aluminum and expensive so there's usually somebody fixing them that might tackle your transmission housings....just a thought.
 
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