Re-anodising boom and holes

[PK123]

Boom - renovation
Ive got a great local company that will remove existing anodizing and re-do that for my boom (which is in need of some love and a little pitted with corrosion). So once its stripped I will collect it and prepare with progressively finer wet and dry before taking back to the factory to be re-anodised.
Im wanting to fill some old redundant drill holes with Bernzomatic fluxless welding rod or HTS-735-II. IM clued up about heating the metal not the rod, and preparing the surface back to bare clean metal etc. But in particular:
1/. I'd need to grind any filled holes level with the surrounding surfaces and wondering about workability/ tiny air voids after the weld has cooled.
2/. Im also wondering about the re-anodising process as the holes will be filled with a different aluminium than the boom (I believe they are 12-20% silica based as fluxless rods and have a lower melting point of around 750 degrees rather than the 1220 of aluminum).
3/. Am I better of filling , priming and painting with something like Awlcraft 2000?
Thanks in advance!

 

[PaulK]

The anodizing guys should be able to tell you if the different alloys will make any difference. The Awlcraft question depends on how much work you want to do (prep for aluminum will not be simple) and the cost compared to re-anodizing.

 

[dLj]

My question is why do you want to fill the holes? Just esthetics? If there is no other reason I would not go through the added work.

Yes, the anodize will not be the same on those spots - I agree with @PaulK best to talk to your anodizer, but that weld chemistry as far as I know will be rather visably different. Your anodizer will be able to advise better than we can.

dj

 

[thinwater]

I STRONGLY suggest you try out those rods on a scrap of mast or boom first. Brazing aluminum is not NEARLY as easy as they make it sound, in part because the aluminum will draw the heat away very quickly. The videos usually show an acetylene torch. TIG welding is pretty much to only way you will succeed, and the result will be weaker than if you leave them along. The best treatment is probably to stick in a rivet.

I've brazed small things, but when I tried something larger, I could not maintain metal temperature with propane. A disaster. I can weld.

Sorry.

 

[PK123]

UPDATE: The anodizing guys have said that brazing rods will be fine but will most likely come out a different colour ranging for grey to black. They recommend that anodizing will be most successful with 5356 rods such as by lincoln electric - which need argon gas for best results. The advice also is that brazing the aluminium will however change the molecular arrangement of the aluminum locally and so unfortuanly there will most likely be a dis-colouration 'spot' of bloom in the anodizing no matter how perfect a repair job of filling the hole is made. The best and no doubt easiest option is to fill the holes with rivets once all anodizing is done (as suggested here). Thanks for the observations!

 

[RitSim]

There is probably also a weakening in the heat affected zone which will be larger than the holes. What about powder coat? Don't know the powder coat fusing temps, but it might be low enough that the holes could be filled with epoxy prior to coating?

 

[PK123]

Thought Id show a photo sent to me from the Anodizers to show the kind of discolouration from a welding repair due to heat and different welding material (taken from another project). Good to have expectations managed.that re-anodizing will not restore it back to 'as new' condition.