Another Metal Use Question for cr1 or anyone else

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Forum topic by Dallas posted 12-09-2011 05:31 PM 1471 views 0 times favorited 9 replies Add to Favorites Watch
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3599 posts in 3574 days

12-09-2011 05:31 PM

I started to post this on the tool steel thread, but thought it might do better here and not drift the other topic off into the wild blue yonder.

cr1, If I may digress from the subject of steel for a moment…. I would like to you or whoever is knowledgeable to discuss aluminum and aluminum repair.
More precisely, let me start this by saying that I do a lot of RV repair work, much of it repairing breaks in aluminum studs, brackets and fixtures that go into the typical cheapy built RV.

While I can TIG or MIG the aluminum, it’s a real pain to drag all the equipment from the shop out to the interior of an RV, (Your choice of brand or type inserted here), For a long time it was the only way to do the job. Sometimes this meant tearing the rig apart so that I could keep from destroying other parts.

Lately I’ve been replacing some doors on an antique Avion pull camper, (like an Air Stream), and since Fleetwood doesn’t carry these doors, I have to build them from scratch. I have been trying out some aluminum brazing rod called Alumiweld, that does a very good job of filling and connecting the tubes and angles more easily than TIG or MIG.
I’ve even used it to repair a broken flange on a cast aluminum pump for a pressure washer, and so far it’s held up for three years of hard use.

As a test I tried joining a copper fitting to a piece aluminum and it seems strong, and survived my non-scientific strength test, (I beat on it with a 20 oz. ball pien hammer), and I couldn’t break the joint.

My question is, is there a long term detriment to using this stuff? As in corrosion problems, dissimilar metal reactions, strength problems for the base metal?

Since it flows at about 730°F, and works nicely with a Mapp or propane torch, the ease of use in an RV environment makes it almost ideal. I’ve even made overhead joints and vertical up joints with it.

Let’s hear from you guys!

-- Improvise.... Adapt...... Overcome!

9 replies so far

View Bertha's profile


13615 posts in 3780 days

#1 posted 12-09-2011 06:15 PM

You need to talk to August Lehman III, not that Cr1’s any slouch. August’s got a Bridgeport, etc. and works will all kinds of metal, including cast iron. He hasn’t been around for a while but he knows his stuff. Philip Marcou obviously knows his stuff, too, but he’s been in absentia for a while too.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View MrRon's profile


6026 posts in 4330 days

#2 posted 12-09-2011 07:38 PM

I’m glad you have tried alumiweld with success. I bought some, but haven’t tried it yet. I use a lot of 6061-T6 aluminum and some 6063. I’m not sure if alumiweld works on aluminum that has an anodized surface treatment. I have done some repairs on aluminum aircraft panels, but they are time consumming. It involves cutting out a piece of the panel, inserting a patch with a backing plate and riveting it together. I think there are epoxies now that are formulated for aluminum. Try or 3-M.

View Dallas's profile


3599 posts in 3574 days

#3 posted 12-09-2011 07:51 PM

Thanks Bertha, I’ll be happy to listen to anyone that knows more about it than I do.. which is just about everyone.

MrRon, This stuff is interesting to say the least. Here is a picture of my very first attempts:

A different angle:

Yeah, I know it’s not a spectacular job, but there is a short learning curve to it. Always remember to keep the torch moving and don’t use a high flame. Don’t put the heat on the rod, let the metal heat up and the rod will suck into it like silver solder.
I spoke with a friend awhile ago and he says he repaired the A/C condenser and the aluminum radiator in his little pickup when he ran a branch through it while out looking for mushrooms.

One question I thought of is if used with aircraft does it have to have an FAA certificate or something?

-- Improvise.... Adapt...... Overcome!

View Bill White's profile

Bill White

5350 posts in 5047 days

#4 posted 12-09-2011 09:04 PM

All you alchemists scare me. I wish I knew more about metalurgy. It is an art unto itself.

-- [email protected]

View Dallas's profile


3599 posts in 3574 days

#5 posted 12-12-2011 05:52 PM

Bill, the only alchemy I can perform is to turn gold into someone elses.

-- Improvise.... Adapt...... Overcome!

View MrRon's profile


6026 posts in 4330 days

#6 posted 12-12-2011 07:45 PM

If used on aircraft, it would have to be an approved procedure performed by a certified mechanic; may not be required for experimental aircraft.

View jmos's profile


918 posts in 3456 days

#7 posted 12-12-2011 07:54 PM

I’m no metallurgist, but won’t you get galvanic corrosion with a copper and aluminum joint?

-- John

View LelandStone's profile


90 posts in 3600 days

#8 posted 12-12-2011 07:59 PM

That’s actually pretty cool! Aside from cold forming (raising and sinking hollow shapes) and hot forging some Hunter/Jumper shoes, I’ve never worked aluminum and didn’t know you could join it with a MAPP flame. Was there a flux needed with this process? What’s the difference between the melt temp of the filler and that of the parent material?

I dunno, it looks to me like you got good flow on your joint there.

-- Leland, OC California

View Dallas's profile


3599 posts in 3574 days

#9 posted 12-12-2011 10:41 PM

I did some research, (what little I could), and it seems this stuff has a high zinc? content.
Since it has a melting temp of @ 732°F, it’s pretty close to the melting temperature of aluminum itself, in fact, I melted some thin pieces of aluminum with the flame too hot

Leland, there is no flux required, but you do need a clean stainless steel brush. I have been using aluminum oxide sand paper to clean the base metal then brushing it well with the stainless brush. Once you have it clean, immediately put the heat to it or your work is wasted and you’ll need to start over because the oxides start up again as soon as you quit brushing.
Keep the heat moving between the pieces with more heat going to the thicker piece. Rub the rod on the hot metal until it starts flowing, then work it back and forth deep in the puddle to remove oxides as it goes. I switch ends often because it scratches better.
Keep the flame off the rod or you’ll end up with a very short rod.

Try it, it’s kind of fun to work with and it doesn’t take much rod to make a good joint.

I’ve also contacted the company about buying in quantities and becoming a distributor. They told me they have filled all the distributorships in this area, but that I could get a decent discount by buying in bulk.

-- Improvise.... Adapt...... Overcome!

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