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  #11  
Old 04-27-2017, 02:55 PM
elavir elavir is offline
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If I had to make a guess I am with Carey, oxidizing flame.
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  #12  
Old 04-27-2017, 03:09 PM
robtg robtg is offline
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Anodized sheet or maybe 2024?
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  #13  
Old 04-27-2017, 08:43 PM
crystallographic crystallographic is offline
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Default It is not ---

Okay - all I was given with this problem was:
Aluminum gas weld looks like this - why?

Okay - so what I can see from these two images:
Not the filler (4043, brazing filler, HTS whatever, lumi-alloy, dura-fix etc etc)
Not the flux (wrong flux, brazing flux, dirty flux etc etc.)
Not the alloy (2119, 2024, 5086, 7075 etc etc.)
Not the water (iron deposits, distilled, radiator water, swamp water etc etc.)

Hint: There is inconsistency in the weld - top and bottom/root, but the weld never gets "good" - just nasty/funky to "almost acceptable ..... at its best point."
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  #14  
Old 04-27-2017, 09:37 PM
Dyce Dyce is offline
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Tip was to small?
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  #15  
Old 04-27-2017, 09:45 PM
cliffrod cliffrod is offline
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Quote:
Originally Posted by crystallographic View Post
never gets "good" - just nasty/funky to "almost acceptable ..... at its best point."
sounds like what both of my ex wives said about me...

Seriously, when mechanical things vary inconsistently in use, it often means something is loose and moving around when it shouldn't be and blocking free movement of something else like trash in a carb or a loose wire/bad connection.

So that might suggest regulator issues varying pressure, connection issues or maybe hoses deteriorating on the inside. No idea what's in a flashback arrestor but they are made to interfere with flow in specific situations so if they were malfunctioning, that could also cause issues.
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  #16  
Old 04-27-2017, 09:53 PM
robtg robtg is offline
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Welding in the wind?
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  #17  
Old 04-28-2017, 02:03 PM
Bob Foster Bob Foster is offline
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Problem with the regulator?
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  #18  
Old 04-28-2017, 03:44 PM
Johnny C. Johnny C. is offline
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Hi Kent, Looks like some deep scratches might indicate an attempt to clean the sample with abrasives rather than chemicals or stainless brush. If aluminum oxide paper was used some of the grit might have been embedded or left on the surface. If so the aluminum oxide might have been too much for the cleaning action of the flux to handle.
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  #19  
Old 04-28-2017, 05:01 PM
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I have not gas welded much Alum. but here goes.......
The filler is not flowing out into the base metal. which would tell me not enough heat.
the surface of the bead looks oxidized, like it solidified out of the flame envelope.

So My conclusion is that the torch was at the wrong angle or lifted after each rod dip allowing O2 on the molten alum.

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  #20  
Old 04-28-2017, 09:27 PM
crystallographic crystallographic is offline
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Default the answer

The problem was loose fittings.

Which gave erratic results on top and root sides. But a more distinct lack of flow occurred on the top. This scenario also included two fittings that could not be adequately tightened and still leaked.

When the O/F has an inconsistent flow, the weld bead is affected both top and bottom, but the variations will be different on the top than they are on the bottom/root side.

This was a classic case.
Thank you, everyone, for your analyses. It was a fun bit of Holmsian scrutiny, wasn't it?
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