Aluminum Brazing

[Pat]

Has anyone here had any experience with an aluminum brazing product called HTS 2000? A friend that works in a sheet metal shop gave me about 15 rods and told me that it really works, and is not like most of the other brands. I watched the HTS 2000 video and was amazed at how easy and strong the joints appear to be. The guy in the video made it appear that he could do anything with this wonder rod. My friend at the sheet metal shop showed me an old pop up camper that belonged to another employee. They used this rod to repair some damaged areas on the camper. Other than the paint missing, the repairs looked just as smooth and strong as the original surrounding metal.

I went out in the shop and found several scraps of aluminum to give the stuff a try. I am not having much luck getting this stuff to cooperate. It will stick to one piece, but not the other. I then tried it on some 3/16" aluminum sheet. Once I heated it enough for the rod to melt on the parent metal, I tinned the 2 pieces, then filled in the joint. After I was satisfied that I had good fusion, I let it cool for about 10 minutes. I then picked up the brazed item and dropped it on the cement floor. It broke in 2 pieces with all of the added filler sticking to one piece. I then put the piece with the filler attached to it in a vise and gave it a slight smack with a small hammer. The filler flew off, and there were hardly any areas on the metal that looked like the filler had any fusion.

I looked at some of the items he had used it on, and I must say they looked like very well made joints. There must be something I am doing wrong, or he was BS-ing me and used something different. He stated that they had tried muggy something and it was a pain to use, and some of the other brands just did not work at all..........thanks for any information on this stuff.

[Harvuskong]

Pat, the stuff that I have on hand is over 15 years old. So this is based on what I have been using on irrigation pipe in the past.

Clean both pieces with a stainless steel wire brush. The key, I think, is using a truly stainless steel brush to get any and all contamination out of the metal.

Years ago, the chinese made "stainless steel" wire brushes did not work. The man demoing the stuff at a farm show told me about having problems at another farm show until he changed over to a new stainless steel brush made in the USA. Then his demos started working like they were supposed to.

You should have much better luck using the rod after using the right wire brush for cleaning.

And you will need to get the base metal hot enough to melt the rod and soak into the base metal. Force it into the base metal while brazing it. It has to soak or combine with the base metal while it all is at the right temp.

I do not think that tinning the base metal by itself is going to be good enough.

[Pat]

Harv,

Thanks for the info. I will get a different stainless brush and see if that helps. I will also try brushing it while it is hot. I guess brushing it hot will help remove more of the oxides.

[Ironman]

Pat, I have a product here that is called HTS-735
It seems to work well, but they stress over and over not to put the rod in the flame.
They say if the work is hot enough the metal will flow under the oxide and lift it.
Your braze joint sounds like a cold joint to me.
This stuff I have melts at 700 degrees.

[Pat]

Gerry,

Thanks for the information. When I was looking at the web site for the HTS 2000 they showed another rod (HTS 528) which I guess is for cast and other steel. I am wondering if the one that you posted is the older version of this brazing material. They refer to this stuff as the 2nd generation filler. More than likely you have the better stuff. They probably had to remove some harsh (needed) component to comply with EPA or another agencies regulations on safety, so came up with the watered down 2nd generation version.

I don't know how these rods come new, but the ones given to me have a whitish.grayish powdery coating on them. I am going to try cleaning that stuff off and see if it helps. Their add says that this type melts at 728 degrees. I have been using a Mapp Turbo torch, but can use my Oxy/Mapp and toss some more heat into it. I will use all these tips I have been given and hopefully get this stuff working. I have 2 aluminum screen doors to try saving. The metal is too thin for the spool gun.

[Harvuskong]

Originally Posted by Ironman

Pat, I have a product here that is called HTS-735
It seems to work well, but they stress over and over not to put the rod in the flame.
They say if the work is hot enough the metal will flow under the oxide and lift it.
Your braze joint sounds like a cold joint to me.
This stuff I have melts at 700 degrees.

I will agree with not melting the rod with the flame, merely get it hot but not hot enought to melt it with the stuff that I have.

The proper procedure is to get the base metal hot enough to melt and flow the rod into the base metal aa long as the base metal is kept hot enough to melt the rod.

Originally Posted by Pat

I don't know how these rods come new, but the ones given to me have a whitish.grayish powdery coating on them. I am going to try cleaning that stuff off and see if it helps.

I strongly agree with cleaning the powdery coating off the rod.

The only aluminum rod that I have ever seen with a coating of any kind was arc welding rod. And I have no idea how well they worked.

[DrBob]

Pat I have been following this thread without comment as I have no experience with HTS 2000 or HTS 735. I have however about thirty years experience with soft and hard solders, silver solders and brazing rod.

I thought I'd chime in because I noticed that your purpose was to repair aluminum screen doors.

If the metal that the screen doors are made of is less that about 18 gauge, you're going to have a hard time heating it enough without wrecking the metal. In my experience it tends to oxidize and even burn through. If it is not thick enough, you might consider some options:

1. repair brackets made of aluminum flat or angle with aluminum pop rivets
2. Same as above with reinforcement by soft aluminum solder using aluminum flux and temperatures below 300DGS F.

As everyone has said soldering and brazing is all about clean clean and clean.
Just about ANY aluminum oxide will prevent a bond. The cleaning should be done within 15 minutes of the brazing/soldering as the clean aluminum will actually re-oxidize from the moisture and oxygen in the air!

I have used a variety of soft and medium hard aluminum solders to reinforce repair brackets with very good results. The thinner your door material is, the more I recommend this over straight brazing or spoolgun welding.

My $.02

Good Luck

DrBob

[Harvuskong]

Hopefully he was able to repair the doors successfully.

If not, there must have been a big blob of melted material on the bench or on the floor.

Thin aluminum is a real challenge for sure. I have not had much success with it either.

[Pat]

Dr. Bob and Harv,

We had some major breakdowns at work, and I had to go in because I was stupid enough to answer the phone. Anyway's, I have not had the time to work on the screen doors, and will probably follow your advice Dr. Bob. The doors are actually in pretty good shape, except for the joints by the hinges and corners that are broken and wobbly. It would be a shame to have a whole corner disappear and ruin the door. Yep, brackets and rivets sound good for now. I will try to pick up an old aluminum door at the recycle center to practice on, and if I have any luck and feel brave, I will then try repairing my own.

I just came back in after using some suggestions in regards to working with the HTS-2000 wonder rod. I used a good stainless brush to prep the joints, then used some acetone to clean them. It made a really big difference. I also tinned a few spots, and while the filler metal was still fluid, I worked it around with the wire brush as suggested by their instruction video.. I seem to have a better working relationship with this stuff now, and will practice on some more scrap. I am kind of leery about their claims of being able to form new mounting ears on alternators, transmission housings, etc. Yes, maybe I could make a new mounting ear, but from what I can tell from my destructive testing, is that this stuff may be too brittle, and crack the moment a bolt starts applying some clamping force to it. I think making a new mounting tab or ear using the spool gun would be a much stronger fix. Thanks for the responses, and I will continue to play around with this stuff.

[DrBob]

They say, "If you only have a hammer then every problem looks like a nail."

While I'm sure you can repair the corner with the straight HTS 2000, I'd be willing to bet it wouldn't take too many door slams for the repair to crack. A nice aluminum mending plate (flat, L shaped plate) with some aluminum pop rivets and then clean the heck out of it all. Use the HTS 2000 to reinforce the repair. I bet it'll outlast the door.

Have fun.


DrBob