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noahvale
12-06-2009, 07:10 PM
I was picking up some welding rods at Harbor Freight the other day and saw these: http://alumiweld.com

They only cost $6 so I figured I would give them a try. The key is to get clean, raw aluminum to
braze. A wire wheel grinder works well. I was amazed at how good they work. It takes much less heat than brazing steel and really goes quickly.

I might just be building some aluminum framed bikes..

chainmaker
12-06-2009, 07:38 PM
That seems pretty cool, obviously there are parts that have to be made of welded steel , but I would think that for frames this would be a no-brainer...my project is going to top out at around 90 or more pounds shaving some weight would be great, has anyone else used somthing like this??? Pros/Cons..keeping a keen ear to this.
CHEERS
:punk::xmas:Chainmaker:xmas::punk:

jimmythekid1
12-06-2009, 08:46 PM
I would assume it would have the same weakness of brazed steel. So I wouldn't recommend using it on parts that are going to flex allot.

Odd Man Out
12-06-2009, 08:51 PM
Be sure to search this site for posts on aluminum and alumiweld -- not sure if the thread was on the old forum but the consensus on alumiweld was that it would be good for non stress bearing structures but not for those that are. Remember that if something sounds too good to be true....

Also I caution anyone from making frames out of AL if they are NOT going to have the frame professionally heat treated when done -- you will be looking at an accident waiting to happen if you don't. I have experience with the "evil metal" aluminum. I personally love it but only when heat treated for stress bearing surfaces,

TheKid
12-06-2009, 09:49 PM
I've used them. Sometimes it holds up to the hammer test, sometimes it doesn't. Even when it did, over time, the joints had a tendency to crack when under constant pressure. That may possibly be due to not being post-heat treated, but I wouldn't trust this stuff with anything that supports weight, or the stresses of a bike frame.
It did work well for things like plant hangers that didn't hold anything heavy. But rivets work just a well, are easier to work with, and are less time consuming.
OMO, IMHO, is the resident expert on aluminum in these forums, so whatever he says about working with "the evil metal", can be taken as fact.

trikeman
12-06-2009, 11:30 PM
I would assume it would have the same weakness of brazed steel. So I wouldn't recommend using it on parts that are going to flex allot.

I doubt that it is anywhere near as strong as a brazed steel joint, since it is basically an aluminum solder.

Contrary to some popular opinion, properly designed brazed joints can be as strong or stronger than the steel they join. This is evidenced by the millions of brazed frame bicycles and even race car frames that have been produced and ridden over the last 100 years. The secret to a good brazed joint is understanding that most braze fillers have about 1/3 the strength of steel. A simple butt joint of two steel tubes joined by the same thickness of brass, for instance would only be about 1/3 as strong as the steel. To overcome this, most builders either use "lugs," which are basically sleeves fitting over the tubes. The lugs give a lot more surface area for the bronze to bond to making a joint stronger than the tubes. When lugs are not used, a filet of bronze thicker than 3 times the thickness of the tubes is used.

A well brazed and finished filet bicycle frame makes most TIG, MIG, O/A welding, stick, and whatever else you have look like bird poop.

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/1973%20Super%20Sport%20CJ809208/CIMG5604sm.jpg

That said, none of Brad's designs were conceived to be brazed. Several members have built brazed Brad designs with proper attention to joint design, but you are on your own there.

Odd Man Out
12-07-2009, 12:04 AM
OMO, IMHO, is the resident expert on aluminum in these forums, so whatever he says about working with "the evil metal", can be taken as fact.

Thank you kind Sir but as Ronald Reagan once said:
"Trust but verify"

StevefromOH
01-05-2010, 01:10 AM
I've used them in the past and they did hold up but results depend on the type of aluminum you are using.

I have found that certain grades of aluminum "braze" better than others. Sometimes the braze will not stick to the aluminum and the braze will just fall off and not stick. It depends on the type of aluminum you are trying to braze.

I have tried to braze aluminum with that type of rod and you have to be careful that you do not overheat the aluminum as it will melt very quickly.

Best way to join aluminum IMO is by tig welding. Can't beat a good tig weld on aluminum. Best investment I ever made welding wise was getting a tig welder.

And yes, heat treating is a necessity when welding aluminum.

Best bet is to get some good chrome molly tubing and braze that. Just too many problems with aluminum to make home building with aluminum successful.