Author Topic: Welding rod type for teens cases?  (Read 690 times)

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Offline steveale

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Welding rod type for teens cases?
« on: 02 Nov 2016 at 21:29 »
As you may have read on my blog, an unfortunate accident on a support trailer resulted in my 1913 cases getting cracked during the MC Cannonball.

Does anyone have any guidance on rod type for TIG welding the cases during repair?  Looking for any insights that may help shortcut the trial & error approach. 

Offline Dewey

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Re: Welding rod type for teens cases?
« Reply #1 on: 04 Nov 2016 at 01:22 »
I can only suggest some things having learned the hard way in Douglas case welding. I'm going to assume the alloy is of CuAl. This in itself is an obstacle. There is a rod , 4145, that has the highest Silicon content that is supposed to be well suited to the 2xxx alloys. Supposed to be. I had no luck with it. First and foremost - the casting is very old and quite simply is aged and therefore brittle like an old persons bones. The casting is also full of impurities even when new and now has oil in all of its pores further adding difficulty to the welding process. Taking a step back, a word of caution. Do NOT put the case in an oven! It only ages it more.

The case I was working with had been successfully welded sometime in its past. The weld filler looked like bright, shiny pure Aluminum and not the slightly grayed appearance of the usual 4340 everybody runs to. Its not a matter of the compatibility of the rod as much as what the welding stress does when it cools. Major cracks! I'm not talking fissures adjacent to the weld - you get them too. I'm talking about the whole thing wanting to break apart in other areas. I tried blanketing too - no dice.

Find a weldor who has had successful experience with this alloy before any attempts on your part. I'm not saying you can't do it yourself, but this alloy is unlike anything else so prepare yourself as much as possible. The general opinion towards the 2xxx alloys is they are un-weldable. You can fill low spots in gasket surfaces without much trouble but repairing structural areas are tough.

I wish I had a junk casting to experiment with because I think repairs can be done with special procedures but I have as yet to find anyone who knows what they are.
 
Dewey
If you do successfully repair your casting I'd very much like to know how it was done.

Offline eddie

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Re: Welding rod type for teens cases?
« Reply #2 on: 04 Nov 2016 at 08:51 »
Steve,
          As Dewey says, it is a good idea to get hold of a genuinely scrap Douglas casing to practice on, before doing further damage to yours.
 Now, a bit of advice that may help. When I needed to have some welding done on postwar crankcases that had previously been gas welded, most of the welders that I contacted said that it couldn't be TIG welded as there would now be too many impurities in the metal. At the time, it was easier to find a pair of unmolested cases and start again. Later, when I built the four cylinder special, I entrusted the work to a welder from the aircraft industry - the finished job was superb - after fettling, the welds were invisible, so I took the opportunity to pick his brains regarding the other cases being unweldable. He just smiled and said "What you have to do, is adjust the set to AC with a greater bias toward the cleaning phase, then reduce the current so that it does not weld - make a few passes over the area to preclean it (a bit of brushing with a stainless wire brush helps to remove the impurities - don't use an ordinary wire brush, that contaminates the area again) - then readjust the set and do the welding as normal".  I tried it at home, and it works!!

Regards,
              Eddie.

Offline Dewey

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Re: Welding rod type for teens cases?
« Reply #3 on: 04 Nov 2016 at 11:36 »
Eddie,

When he said "readjust the set", did he mean just the amperage or that and the AC balance too?

Dewey

Offline eddie

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Re: Welding rod type for teens cases?
« Reply #4 on: 04 Nov 2016 at 12:00 »
Both the amperage and the AC balance.

Eddie.

Offline steveale

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Re: Welding rod type for teens cases?
« Reply #5 on: 05 Nov 2016 at 00:12 »
Thanks guys!  I do have an old spare case to practice on...will report back but it will be a while before we get to it...

Offline Dewey

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Re: Welding rod type for teens cases?
« Reply #6 on: 05 Nov 2016 at 11:05 »
It seems the original question still hasn't been answered - what filler rod is used?

Dewey