[ljdm1956]

Been trying, not a whole lot of success. That's why I asked about the gas - trying to find out if my lack of success is due to my skill level, or if just won't work without straight helium, and I'm just wasting my time.

[Superiorwelding]

The down and dirty answer is yes you can weld alum on dcen using argon. Now is is suggested or proper, that would depend on what it is you are welding, machine capabilities etc. You will not get the penetration using argon that you would with the helium. I am not around the computer now but there are a lot of videos out there depicting how to weld dcen on alum.

To answer your question on having clean alum and therefore not needing the cleaning action, you will still have a layer of oxides on the surface even with a wipe down and wire brush.

-Jonathan

[dogfood]

@ljd

Read through the thread and gave it a try on EN with Argon gas with similar results, regardless of cleaning-still couldn't break through the "skin." Some beautiful side effects, though. Switched to EP and, with brushed and scotch-brited base metal and rod, got that familiar rounded tip and bead lay. I forget which direction the heat comes from with which polarity but I guess it takes a certain intensity to break the oxide layer that Argon and EN can't deliver.
It's basically AC with the dial turned all the way to one side from the sound and look of it.
Mind you I'm doing this on a big ol' 350 transformer that can do AC, so I'm curious if it'll work on a little inverter suitcase.

D

[MinnesotaDave]

@ljd

Read through the thread and gave it a try on EN with Argon gas with similar results, regardless of cleaning-still couldn't break through the "skin." Some beautiful side effects, though. Switched to EP and, with brushed and scotch-brited base metal and rod, got that familiar rounded tip and bead lay. I forget which direction the heat comes from with which polarity but I guess it takes a certain intensity to break the oxide layer that Argon and EN can't deliver.
It's basically AC with the dial turned all the way to one side from the sound and look of it.
Mind you I'm doing this on a big ol' 350 transformer that can do AC, so I'm curious if it'll work on a little inverter suitcase.

D

It does work on little inverters that can tig. Only for thin aluminum though since the tungsten and torch heat up fast on DC+

Side note: my Miller Maxstar 150s is stick only and won't keep an arc going on scratch start tig. But my cheap little Century does scratch tig fine - weird.

[DeweyO]

I realize this thread started quite some time ago but it's very relevant to a situation I have. It's a old motorcycle case from a historic machine 1932 vintage (Douglas to be exact). It's a copper aluminum alloy, maybe some zinc too, and very brittle. It has the reputation of being unweldable and so far that has been the case. There are cracks in structural areas and all attempts to repair them by many respectable welders have just created more cracks, not just fissures next to the immediate weld. Salvaging this case is of great importance due to it's historic value. AC and Argon was used in all the attempts. I was thinking about the shape of the weld puddle as being a major contributor to the stress that creates more cracks and started thinking if DCEN was used the stress could be reduced. Then I started searching and found this thread. Any input would be appreciated.

Dewey

[MinnesotaDave]

I realize this thread started quite some time ago but it's very relevant to a situation I have. It's a old motorcycle case from a historic machine 1932 vintage (Douglas to be exact). It's a copper aluminum alloy, maybe some zinc too, and very brittle. It has the reputation of being unweldable and so far that has been the case. There are cracks in structural areas and all attempts to repair them by many respectable welders have just created more cracks, not just fissures next to the immediate weld. Salvaging this case is of great importance due to it's historic value. AC and Argon was used in all the attempts. I was thinking about the shape of the weld puddle as being a major contributor to the stress that creates more cracks and started thinking if DCEN was used the stress could be reduced. Then I started searching and found this thread. Any input would be appreciated.

Dewey

Two things to think on in my opinion.

What is the actual blend of material and what filler rod would be the most appropriate based on this information?

2nd, what preheat and postheat treatment would help this situation?

I just welded some 74 Triumph cases, covers and a head. I used 4043 filler and no preheat.
Your cases sound like they would not be weldable in the same simplistic manner.

[dsmabe]

You might be better off using silicone bronze or aluminum bronze and tig brazing from the back side.

[DeweyO]

MinnestotaDave

No one seems to know the exact composition of the alloy. There's one person, possibly the most informed in both the Douglas motorcycle and what and how they were made 80 years ago, who insists they were cast from floor sweepings. Douglas also made aircraft but not the large ones we associate the name with, and as I understand it the Cu Al alloy was commonly used in that field.

I do some welding, including TIG starting back in the 70s, but not profficiently so given it's importance I decided it should be done by someone who does it for a living and has a good reputation. The first welder makes all sorts of things for the medical industry. He put in an oven prior to any welding and finally gave up due to the fissures next to the last bead. We blanketed it overnight and the next morning there was a new crack, not a fissure, in a totally new area. The second welder is a gear maker and repairer and TIGs on the side. He didn't do any preheat that I remember and gave up for the same reason as the first one. The third one welds in a machine shop in another state and it was the same story. The fourth welder is a welding instructor and adamantly insisted preheating is a bad idea with a casting like this. He too reached a point where he didn't want to go any farther. The fifth welder, who has it now and has the reputation that if it can be welded he can do it, tried some 1100 rod on a small area thinking that being softer it would give a little when it solidified, but it didn't make any difference - fissures big time.

I too have repaired Triumph & BSA cases, all with acceptable results. In fact, repairing bike cases for local dealers was the whole reason I got started in TIG.

dsmabe -

I have considered using an Al brazing rod which is Zn/Tin but am afraid to put a lot of heat to this case given its tempermental nature. I'd have to heat it up to a minimum of 730°.

[Otto Nobedder]

This suggestion is a bit "over the top", but...

"Floor sweepings" means 'pot metal', which can be soft-soldered, but not welded by any practical process.

Consider "leading" it, using flux and lead/tin solder to build a new surface on the inside to seal all the pores... You can make one continuous thin surface. I suggest dressing the exterior first, so the high-temp work is done and it appears as it should.

Lead/tin solder will melt well below the temperatures that affect your exterior dress...

Steve S

[DeweyO]

Well, I never gave that a thought but I'll certainly try it. Easy enough temperature wise.

Thanks

[steeldr.]

I developed a welding procedure for welding aluminum pipe, 5 in.diameter and 1/2 in. wall. 60 degree inclusive angle , 1/16 in. landing,with an open root of 3/32 in.I used 3/32 in. thoriated tungsten ground to a point. and torch purge gas of 100% helium , and a flow of aprox. 20 cfm.,and amperage of aprox. 180.... the results of the tests were as follows; P.t.,sat. x-ray sat, bends ( root and cover) sat.
Note; you have to try different torch angles, and distance between tungsten and work (arc length) and cleaning methods, and flow of helium. .......... ron

[DeweyO]

Thanks ron -

You didn't say if it was DCEN, but I assume it is. I'm quite sure the pipe you were welding is a lot more forgiving than this old casting.

I've been playing around with an old dirty broken half of a transfer case using DCEN, pointed electrode, and Argon. 180+ amps and getting full penetration. The unknown electrode did ball up so it may have been straight tungsten. The weld itself was good enough for me if I can get a similar result on this engine case. Too bad it's such a valuable item to be taking chances like this.

I've been thinking of plugging all the holes on the opposite side I want to weld from, filling it with dry sand and covering it with a piece of board, metal, something flat, and flipping it over so when I do hit it with DC it won't drop out on me. That could also absorb some of the initial heat so there would be less spreading out to the rest of the casting and thereby reducing the risk of creating another crack. This is all theory tho -

Dewey

[kiwi2wheels]

@ DeweyO

Any possibility of getting an analysis of the alloy composition by mass spectrometry ?

[DeweyO]

Not in my neck of the woods.

[soutthpaw]

From all the heating, welding etc that has been done on this case, it sure sounds like it's been ruined long ago. I think you are missing the key point. It's not a weldable alloy as you said but you still insist on welding it. You sound like Congress. If something doesn't work, keep doing the same thing over and over again till it does. Time to JB Weld it

[Otto Nobedder]

Well, I never gave that a thought but I'll certainly try it. Easy enough temperature wise.

Thanks

Another thought... Chrome shops deal in pot-metal/random alloys all the time, perfecting surfaces before the copper-plating that precedes the chrome. You might find the expertise you need there. They might even be able to do a brushed nickel plate to simulate the original finish.

Might be worth exploring...

Steve S

[DeweyO]

Thanks for your honesty. I'm just looking for a ray of hope that it can be salvaged, and no, JB weld isn't going to cut it.

[noddybrian]

If someone else suggested this further back than I've read sorry - but when faced with an unweldable alloy would it not be a good candidate for one of the repair alloys such as HTS-2000 or similar ( not advertizing it or have any connection with them ) - heat the entire piece gently - make repair using whichever rod you have most faith in at low temperature ( typically just over 700 degrees nowhere near melting point ) then bury in silver sand to cool as you would cast iron - only downside is color match won't be perfect usually - but it usually holds well - I've done it occasionally on bike casings though not that make - just a thought.

[DeweyO]

nobodybrian -

I have some of that exact same rod and have been contemplating trying it for some time now, although many poo-poo the idea. The cracks are all internal so color matching is not an issue. I'm just nervous about heating so much of the casting as new cracks appear in entirely different areas when fully cooled. The cooling was slowly done after the first welding attempt by wrapping it in a fiberglass blanket (wall insulation). I used some of that rod to repair a Mercedes oil pan in-place and it was a total success, until he T- boned another driver. The car was totaled but the repair held.

[noddybrian]

Well it's your call - the way I look at it you tried a regular weld without success but there will always be localized stress setup by doing this & the temperature difference around the weld despite slow cooling - it should be possible to slowly and uniformly heat the casing to virtually the temperature needed for the rod to take - so the difference where the repair is made will be very slight - the HTS - 2000 is way more forgiving than a normal fusion weld so if the part is cooled slowly enough it should work - maybe try when the wife is out heating it in the oven as hot as it will go then allowing it cool in the oven - if no new cracks appear you stand a very good chance of succeeding - if more cracks appear then it is likely a lost cause & the only solution is find a replacement unless it's super super rare - if so then the only answer maybe to coat it layer after layer of primer filler until you can sand it smooth & oversize enough to use as a pattern & try to sand cast a new one using melted down alloy of known material such as wheel rims or other newer motorcycle parts found in scrap yards - whatever you decide I wish you luck.

[DeweyO]

Super, super rare sums it up pretty well.

[Otto Nobedder]

Super, super rare sums it up pretty well.

Consider having it conserved...

Have a 3-d laser scan taken so it can be replicated, perhaps take a silicone casting, etc., so it can be reproduced before you risk further work on the irreplacable original. Today's technology will allow you to reproduce it with extrememly high accuracy, possibly using the reproducion on the original machine while saving the original casting.

Steve S

[DeweyO]

3D scanning is good advice. Weather a new part is made or not, it would be good to have that digital info readily available.

Thanks -

[soutthpaw]

A lot depends on the machine. Many cheaper machines will not maintain an arc on 100% helium. A Dynasty will, my Everlast will support about 60% helium

[DeweyO]

southpaw - I have a Lincoln Precision Tig 185, square wave , micro start. Not the latest & greatest but sure not Harbor Freight either.