[lr172]

I am still new to Tig and not quite ready to start practicing on Al yet. However, I have an application that I would like to start practicing for. I would like to weld a 1/16" wall alum tube onto a 1/2" alum plate, I could either make this a standard T joint or create a socket for the tube. The 1/2" plate will effectively be 1/2 X 1/2 x 1/2 round, so not a massive heat sink.

Is this a realistic project for a beginner Tig welder? I suspect it could be difficult to manage the heat between the two very different thicknesses. I have 225 amps on my machine.

Strength requirements are low, so could also use brazing, but my limited research indicates that may be more difficult. I do not have an O/A rig.

Thanks for your insight here.

[BugHunter]

That's gonna be super challenging.

A) Not sure the welder is gonna have enough snot to do it.

B) Gonna need a hefty tungsten, don't even bother with 3/32. 1/8" minimum.

C) 100% of the heat MUST go into the 1/2" plate. It's gonna be tough to even get a weld pool started with 225A. Don't even think about pointing at the tubing, keep the arc on the plate. Just the stray heat will be enough to wet the tubing, especially just an end of it.

D) Preheat on the plate is mandatory. Might also consider some of the welding mud around the tubing in order to bleed heat out. Maybe someone here will say if wet rags would work. That 16ga tubing is gonna disappear if you get near it with 200A+.

To start with, I'd get a weld pool started on the plate before I even stuck the tubing on there. Just get an understanding of how much heat it takes to wet out 1/2" plate. It's a lot. If the arc wanders over to the tube, it's gonna blow a hole in that thing like it's foil. Keep the arc tight to the plate. Be sure the tip of the tungsten is balled some, and definitely don't use one sharpened to a point. You need that to carry the arc close to the plate so it won't come off the side of the tungsten if you get close, and burn holes in the tube.

Good luck. Definitely test with no tubing first.

[cj737]

Welding 1/2” aluminum with 225 amps is probably insufficient alone. You definitely need a preheat on the 1/2”, plus, do a vigorous scrub of the oxide layer before welding it.

Settings I’d use, 78% balance, 50-60Hz, and FULL PEDAL! As a new welder, first try welding on the 1/2” alone. You’ll find the challenge there daunting, and you will absolutely need 1/8” filler.

Now the hitch is the disparity to the 1/16” which you could probably weld with less than 100 amps. The ambient heat from the 1/2 weld will pour into the 1/16” and you will be racing to stuff enough filler in to prevent the 1/16” tube from collapsing.

Not a beginners realm for certain, and likely experienced folks would adapt a different strategy if possible. But go for it with some practice and learn. It’s only metal and you can’t learn these things without trying them. Then decide if you can do it for a proper outcome.

[Jakedaawg]

You are saying the 1/2" plate is really a little round piece with a 1/2" diameter and 1/2" thickness? The tubing is 1/2" diameter?

[lr172]

You are saying the 1/2" plate is really a little round piece with a 1/2" diameter and 1/2" thickness? The tubing is 1/2" diameter?

The tubing is 4" X 1/16" round. The plate is round, 5" OD, 3.932" ID and 1/2" thick. This piece has a 1/2" radius milled on it, so from a mass standpoint it is ~25% smaller than 1/2 X 1/2 . The tube will be welded near where the radius terminates, so a bit less mass in that area.

[eelman308]

Got a picture of what you're fabricating?

[lr172]

Got a picture of what you're fabricating?

No. I haven't made the part yet. Don't want to go down this path if I am not able to weld it up. May have to use a larger billet and make it all on the lathe if I don't think I can weld it. It is expensive and a huge material waste if I have to go down that path, so would like to avoid it, if I can.

Anyone ever used the aluminum braze rods for something like this? I could turn a socket in the large part to insert the tube and use a low temp braze rod. Strength is not really an issue here (really only needs to be a bit stronger than JB weld), but not sure if brazing has the same heat problems with the thickness differential. I don't have O/A and fear MAPP is not enough to get the thick part up to brazing temp.

[BugHunter]

The tubing is 4" X 1/16" round. The plate is round, 5" OD, 3.932" ID and 1/2" thick. This piece has a 1/2" radius milled on it, so from a mass standpoint it is ~25% smaller than 1/2 X 1/2 . The tube will be welded near where the radius terminates, so a bit less mass in that area.

Ok, so it's not a plate, it's a ring. And a lightened ring at that. Big difference. Still going to be a challenge but nothing like what I was assuming you meant.

Still not sure where this radius is, inside, outside, on the side the tube attaches or opposite...
A drawing would sure help if you don't have a pic.

[cj737]

Got a picture of what you're fabricating?

No. I haven't made the part yet. Don't want to go down this path if I am not able to weld it up. May have to use a larger billet and make it all on the lathe if I don't think I can weld it. It is expensive and a huge material waste if I have to go down that path, so would like to avoid it, if I can.

Since you have a lathe, can it be internally threaded on the "plate" end then externally threaded on the 1/16" tube? That with some LocTite would be easiest (provided its doable).

[G-ManBart]

I'm far from an expert, but I've been TIG welding for about 8 years now and finally decided to learn aluminum early last year...let's just say it's challenging in the beginning. I actually really enjoy welding aluminum, but it's very different compared to steel or stainless.

I'd suggest you simply get some 1/8" and 1/4" flat stock....2-3" wide strips would work, then try running a couple of beads. After you can weld a decent bead, try a couple of fillet welds with the same size stock. Then try a fillet weld with the 1/8" on the 1/4" and know that what you're talking about is going to be much harder.

All the rest of us can do is guess. Some people pick it up quickly and others take forever...most of us are in between. I know I'd be worried about that project as you describe it!

[Spartan]

I've read through all of the posts, and still can't quite understand the parts and joints you are talking about. A picture/drawing is worth 1000 words when you're looking for advice. Post something graphic if you want accurate advice. Most people here would easily spend 5 minutes or more of their time typing a detailed response to your question, so consider taking 2 minutes of your own time to provide a graphic to help those people help you.

[lr172]

I've read through all of the posts, and still can't quite understand the parts and joints you are talking about. A picture/drawing is worth 1000 words when you're looking for advice. Post something graphic if you want accurate advice. Most people here would easily spend 5 minutes or more of their time typing a detailed response to your question, so consider taking 2 minutes of your own time to provide a graphic to help those people help you.

IMG_1612.JPG (51.41 KiB) Viewed 3749 times

[lr172]

Ok, the drawing got me thinking that I don't need that big of a chunk of metal. The drawing also includes the flange (forgot it in the last pic). If I cut an angle, I can leave WAY less mass near the weld area. I can make that land maybe 3/32 or 1/8 to reduce the mass near the weld. Would like advice on what size to make the land. Also, I can make a step before starting the angle to leave even less mass near the weld.

Thanks for the help here.

EDIT: Even better idea - I can make a tool opposite the radius and turn it such that The whole piece is no more than 1/8" thick in any given place. The radius would be on both the int and ext of the ring with a 1/8" thickness. A bit more work, but probably less than all of the practice necessary to weld something with such a difference in mass. Let me know if the idea above is workable for a newbie.

IMG_1614.JPG (40.18 KiB) Viewed 3745 times

[lr172]

Got a picture of what you're fabricating?

No. I haven't made the part yet. Don't want to go down this path if I am not able to weld it up. May have to use a larger billet and make it all on the lathe if I don't think I can weld it. It is expensive and a huge material waste if I have to go down that path, so would like to avoid it, if I can.

Since you have a lathe, can it be internally threaded on the "plate" end then externally threaded on the 1/16" tube? That with some LocTite would be easiest (provided its doable).

An interesting idea. Thanks. will need to do some research on TPI and major minor Dia's. Wondering if there will be enough meat left on the 1/16 wall tube after threading. While I don't need a great deal of strength, someone could bump into the tube with some leverage and not sure 030" Alum will hold a lot. Due to the radius, I would only be able to get 2-3 threads of engagement.

Also, was hoping to chuck up the assembly on the tube to turn the radius portion and don't think threads would hold up for that. It is a bit more work to make a jig to hold the part for turning without the tube attached.

[eelman308]

I'm thinking threading will be a no go. Between the thin tubing and the bevel / chamfer.....a strong breeze would knock that out. IMHO

That said, welding 1/16 to 1/8 sounds reasonable to me.

[BillE.Dee]

what is the "thing" going to be and do? You can't find 4 inch tubing with a heavier wall? Can you design an interference fit for the tubing into the plate, since you don't need strength for support?

[lr172]

what is the "thing" going to be and do? You can't find 4 inch tubing with a heavier wall? Can you design an interference fit for the tubing into the plate, since you don't need strength for support?

It is a tubing flange that secures flexible tubing to a flat surface for air flow. Standard 90 degree flanges produce a great deal of turbulence and the radius smooths that out and increase air flow through the tube by about 20%

Interference fit is a good idea. I am sure If I add some sleeve reatainer that it would be strong enough, though not sure it will be strong enough to allow me to chuck the assembly on the tube for turning. I suppose if I keep the cuts light it may work. Any idea how much? I know .0015 would work well on a solid part, but wonder how much for a thin walled tube. Will have to research that.

Thanks.

[MinnesotaDave]

For what you are doing, thick-to-thin won't really be that bad.

Once joined, just keep heat to the thick side and the puddle will stay with you.

Add rod to keep joint filled and weld happy.

First time I did something like that was with my old 1963 tig. No balance adjustments, just weld it

[BugHunter]

If it's not going to be subjected to heat, You could even consider Devcon Aluminum Putty. For that, or even still if you're going to weld it, you'd be adding a counterbore to the radius'ed part, with enough length to press the tubing inside it. On that diameter, press fit should be real easy. From there you can easily weld the thing, again keeping the heat mostly on the heavier part. Also you should not need to do quite as much thinning of the ring as you're suggesting above. If it's a press fit, the heat will likely equalized pretty well. Not 100%, but would make welding much easier than two parts sitting alongside each other with no mechanical contact.

Here's what I was thinking. cut a .0625 x .125 counterbore into the ring part. Then insert the tube, then weld at the junction(s). Or, if Devcon would work, use that.

[LtBadd]

Here's what I was thinking. cut a .0625 x .125 counterbore into the ring part. Then insert the tube, then weld at the junction(s). Or, if Devcon would work, use that.

Yes, that's the ticket!

[lr172]

If it's not going to be subjected to heat, You could even consider Devcon Aluminum Putty. For that, or even still if you're going to weld it, you'd be adding a counterbore to the radius'ed part, with enough length to press the tubing inside it. On that diameter, press fit should be real easy. From there you can easily weld the thing, again keeping the heat mostly on the heavier part. Also you should not need to do quite as much thinning of the ring as you're suggesting above. If it's a press fit, the heat will likely equalized pretty well. Not 100%, but would make welding much easier than two parts sitting alongside each other with no mechanical contact.

Here's what I was thinking. cut a .0625 x .125 counterbore into the ring part. Then insert the tube, then weld at the junction(s). Or, if Devcon would work, use that.

Thanks to all for their input and suggestions on this. I will use this approach. I may also run a test with the interference fit with a sleeve retaining compound, as that may be enough strength for this applicatoin. If not, the welding now seems to be in the vicinity of my skill level