3D Joy

I am in the process of welding the header for my ZDZ 80 RV. I purchased the RCS canister and header. The header looks like it is galvanized steel and comes fully assembled. The problem is that I had to slightly modify the offset that was built in the header and made some cuts from the side of the tube so that I can bend a little more so I have less offset. I made a total of two cuts and one of the cuts is too wide to fully "close" as I bend the tube. At the widest point, I have about 3/32" gap to fill with weld material.

My question is, what would be the best way to weld my header appart from TIG welding it, which is hard for me to get done. I have been told to silver weld it and others have said silver solder is too weak for what I want to do and can melt only with the heat of exhaust gases. I am confused...

Thanks for all the help guys.

rcdude7

My Feedback: (264)

I am no expert at welding but when I learned, the shop insructor warned us against welding or brazeing galvanized steel. He said the gasses from it would be very toxic. You are going to have a hard time filling a large gap in a thin steel tube that a header is made of. You may be better off finding some one who can fab a header to your specs using the flange that you already have for your engine.
Sorry if this is of little help, but it sounds like a job better farmed out to some one who knows welding.

Steve Sanford

When I make headers, (race cars, planes, rc planes, etc) I tig the tubes together with a mild steel filler, but when you attach them to the flanges, I use silicone bronze. You could acetelene weld it where you have to with a mild steel rod, and fill it in if you cannot tig it. SS

Mrt1750

My Feedback: (1)

I have that same pipe from RC showcase it seamed to heavy to me and it
did not fit my plane and canister, so I called Desert Aircraft.
I bought from DA flange three 90 degree and 2 straight pipes you may need
more or less the pipes snap together then they can be silver soldered (brazed).
The pipes I bought were 28 MM they also have 25MM ask Dave or Brian they
are very helpful. Don't forget to get coupler and clamps to match both pipe
and muffler size I've attached a couple of pictures to help. Check my web
site for header build pages. You can see the torch I bought from Home Depot
about $40.00 don't forget to get silver rods from DA for brazing.
Thanks

Desertrat

My Feedback: (2)

Ditto Mrt1750. Silver solder will hold up just dandy. Here's mine, not quite as pretty, but this was my first time brazing, and before all the great tips Mike put online here.

Roger

Diablo-RCU

My Feedback: (1)

Before you try to weld or braze the header, find out from RCS exactly what it is made of. I doubt it's galvanized steel. It may be aluminized steel. You can silver solder using a high temperature solder or have it welded. But, I would remove the coating from the steel first.

3D Joy

Thank you all you are all very helpfull.

As for the coating, I was going to remove it anyway as I know if it is galvanized, it will produce bad fumes and if it is aluminized or anything else, instead of welding, I wil be more bonding than anything else --> NOT GOOD... As for material, I am about positive that it is steel with a coating that LOOKS like galvanized.

Here are some pics of the setup. The airplane pic was taken way back and now the ignition is mounted on the left side of the engine box for better cooling and better clearance from the cowling.

rmh

The flex stuff available from KS helps remove vibration to can/muffler /airframe.
This is one I did -copy of one sold by Desert Aircraft.

WRK

My Feedback: (2)

Just a note to say that silver soldering and brazing are not the same thing, brazing will take more heat and will fill gaps if done right>

Antique

My Feedback: (4)

Roger (Desert rat) ----- What silver solder do you use that will stand up to the exhaust heat ???

Desertrat

My Feedback: (2)

Antique: I used the stuff DA sold me (flux coated), but I'm sure its no different than the high temp silver solder sold at Home Depot. I was worried about the temp as well, but you have to get the metal red hot before this stuff melts... I hope the exhaust never gets that hot, if it does, I think the solder melting would be the least of my problems. I got about 15 flights and 10 ground runs on the exhaust pictured above, total about 20 hours of run time, most of that header is cowled, good flow in the air to cool, but not much on the ground runs - to date, no evidence of melting and no leaks. I'm no welder by trade, I've sweated a few copper water pipes, this was my first hack at the high temp stuff... brazing... soldering... <shrug> I melted the flux coated stuff in the joint thingy, using a torch I bought at Home Depot, and its all holding together nicely It was like playing Monster Garage.

Roger

Diablo-RCU

My Feedback: (1)

Brazing and soldering describe the exact same process. The only distinction is that solders melt at lower temperatures. High temperature silver solders are brazes.

Borrowed from the net:
What is the difference between brazing and soldering?
Brazing - The AWS defines brazing as a group of joining processes that produce coalescence of materials by heating them to the brazing temperature and by using a filler metal (solder) having a liquidus above 840°F (450°C), and below the solidus of the base metals.

Soldering - Soldering has the same definition as brazing except for the fact that the filler metal used has a liquidus below 840°F (450°C) and below the solidus of the base metals.