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  #31  
Old 08-31-2011, 10:27 PM
PaulG PaulG is offline
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Default Brazing Aluminum Panels

I am sure everyone here will say I am crazy, but you might not if you tried it.

A few years back I built a car from the frame up and brazed the 3003 body panels with a torch. By the way, I have done it with tig sense, and prefer that method.

Anyway, If your willing to make the effort, braze two test pieces together and put them in a vise anyway you like and bend them till they break. Do that as many time as it takes till you are convinced that the brazed joint will not fail. They won't break at the joint. You don't melt the aluminum and the braze filler is softer than the aluminum so there is no cracking. The seam is flat and soft. Finishes even easier than a gas welded seam. Brazing is much faster than welding using any method. Oh yeah, and unless you overdue the heat, you will never have to go back and fill the holes you blew threw.

I have tried many brazing rods, none has worked well for me but one. I would to know if someone has found another
https://www.tinmantech.com/html/aero..._flux_core.php
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  #32  
Old 09-01-2011, 10:23 AM
bryanwi bryanwi is offline
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I really don't know about panels at all. (And read this and similar threads with interest.)

I have one observation that might be somehow informative.

Ti bicycles are tig welded. I've never seen one done any other way. (Thin walling tubing for weight.) [With argon filling in the tubes, so there is atmo control on both sides of the weld]

Steel bicycles are either brazed with lugs or tig welded. I've never seen an OA welded bicycle.

I don't recall how aluminum frames are done now.

P.S. Weirdly, the only welder I happen to own is a MIG machine, and I pretty much hate mig...
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  #33  
Old 09-01-2011, 10:54 AM
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Hey Scott,
What grade aluminium do you want to weld?

I have had great success with welding aluminium both Oxy/acetylene and TIG. All the bodies I have fabricated, 5005 Series Aluminium was used. I have no major preference to which is better, I enjoy welding aluminium both ways but chose to Tig weld due to the flux needed for oxy and the fact that it could get trapped in vacancies or miniscule pin holes that you can't see and then hammered into and closed over then intern corroding a patch in the panel.

5000 series aluminium can be welded autogenously meaning without a filler alloy, if a filler is needed parent metal can be used in both Oxy and Tig by cutting a thin rod off the edge of the sheet. When welding with Oxy I would first have the weld joint a perfect fit and then stainless steel wire brush the edge on both sides to remove the oxide and clean with acetone. To flux the rod I would pour the flux into a folded v tray, warm the rod and lay it in the flux, clamp to get the tack started and continue with tacks until ready to weld and then weld... Done! Then to clean the flux I would wash with boiling water and more wire brush to ensure it was very clean.

When welding with the Tig I would wire brush (stainless) the edges on both sides to remove the oxide and then finish with scotchbrite, wipe and clean with acetone. I would then tack and wire brush the tacks before welding as oxides form on the tacks. I then back tape with welding tape to trap the sheilding gas and push out the air, pre warm the panel and weld continuously fusing without filler, flip the panel take off the tape wire brush the back of the weld, check panel temp and warm again if necessary and then fuse again. There is no need to anneal the panel as the tig is just a heat source as is the oxy but the heat affected zone is narrower so therefore the annealed area is less. I do not anneal the panel and don’t have any problem with cracking.

I have attached some pictures, I hope this helps.

workshop 031.jpg

workshop 042.jpg

workshop 051.jpg

workshop 083.jpg

workshop 114.jpg
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  #34  
Old 09-01-2011, 08:01 PM
SATAUS SATAUS is offline
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Default TIG aluminium bodie panels

Hi Jamie,

Thanks for the reply.

This is great information just what I was looking for.

The aluminium I want to weld is 5005 this is what I use to make all of my projects.

I TIG weld all my projects because thats what I have and I cant justify Oxy/acetylene because of bottle rental, this is just a hobby for me.

1) When you wire brush your aluminium do you use a hand brush or a machine brush to do this?

2) The back tape you use what is it called and where do you get it?

3) Do you put an extra hose (and flow gauge) in the tape to purge with gas or just put the tape on the back of the panel with no purging?

4) "pre warm the panel" how warm should it be, warm to touch or so warm you cant touch it and should it be warmed just in the welding zone or the whole panel?

Thanks for your help in advance

Scott

ps the quality of your work is fantastic
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  #35  
Old 09-01-2011, 10:03 PM
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Default Buying bottles...not in So Cal.

The So Calif Air Board requires bottles be re-certified each year. So you can't buy them anymore. I sure miss owning mine. Fred26t
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  #36  
Old 09-06-2011, 04:05 AM
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Hey Scott,

Sorry for the late reply.

1) When you wire brush your aluminium do you use a hand brush or a machine brush to do this? A hand wire brush is all I use, a machine wire brush tends to drag the aluminium.

2) The back tape you use what is it called and where do you get it? It is called "welding tape" it is high temp adhesive aluminium tape with a fibreglass center strip, I buy it in bulk. I wasn't able to find it locally. I can supply you with some if you can’t find any.

3) Do you put an extra hose (and flow gauge) in the tape to purge with gas or just put the tape on the back of the panel with no purging? No I find that the gas that falls through the weld joint is enough to shield the back of the weld.

4) "pre warm the panel" how warm should it be, warm to touch or so warm you can’t touch it and should it be warmed just in the welding zone or the whole panel? I heat the whole panel with the Oxy keeping away from the weld area so not to contaminate with the flame. The panel needs to be heated enough to get the chill or moisture out of aluminium, water boils at 100 degrees Celsius, lick your finger and touch the panel to check or drop a small amount of water on the panel.

Good luck and let me know how it goes.
P.S. thanks for the compliment
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  #37  
Old 09-06-2011, 05:35 AM
Peter Tommasini Peter Tommasini is offline
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Default tig versus oxy for aluminium welding

Just to add to the discussion about mig versus oxy welding of aluminium. My thoughts are you should stick with what works best for you. I personally still oxy weld aluminium but I have seen Jamie from Kustom Garage building a complete vintage car body in aluminium and welded entirely with the tig. To my surprise there was no problem with cracking and was metalfinished very well. As I previously was not a big fan of tig welding I was amazed by this. Even though I have been building bodies for a long time, I am thinking of giving the "tig" a go myself. It just goes to show you can teach and old dog new tricks. I am particularly interested in testing the strength of the weld to see how it compares with the strength of the oxyweld. Most people say they have a problem when it comes to the flux interfering with the paintwork. I have not encountered any problems. Its all about how you prepare and clean it. Like to hear your thoughts.
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  #38  
Old 09-06-2011, 06:51 AM
SATAUS SATAUS is offline
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Default TIG sheet steel

Hi Jamie,

Thanks for the reply and thanks for all the answers to my questions.

I will try to find some tape, if I can't may get back to you for a roll to try if thats OK.


Hey Peter,

With your skills your one old dog that will learn this trick.


Scott
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  #39  
Old 09-07-2011, 02:39 AM
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Quote:
Originally Posted by www.kustomgarage.com.au View Post
Hey Scott,


2) The back tape you use what is it called and where do you get it? It is called "welding tape" it is high temp adhesive aluminium tape with a fibreglass center strip, I buy it in bulk. I wasn't able to find it locally. I can supply you with some if you can’t find any.

Thanks Jamie,
Like Scott I'd never come accross this product before. Now I know it exists I've found a few retailers in the UK who advertise it. As usual none of them advertise a price!
But I think it warrants further investigation. Thanks for sharing.
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  #40  
Old 09-07-2011, 07:25 AM
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Quote:
Originally Posted by PaulG View Post
I am sure everyone here will say I am crazy, but you might not if you tried it.

A few years back I built a car from the frame up and brazed the 3003 body panels with a torch. By the way, I have done it with tig sense, and prefer that method.

Anyway, If your willing to make the effort, braze two test pieces together and put them in a vise anyway you like and bend them till they break. Do that as many time as it takes till you are convinced that the brazed joint will not fail. They won't break at the joint. You don't melt the aluminum and the braze filler is softer than the aluminum so there is no cracking. The seam is flat and soft. Finishes even easier than a gas welded seam. Brazing is much faster than welding using any method. Oh yeah, and unless you overdue the heat, you will never have to go back and fill the holes you blew threw.

I have tried many brazing rods, none has worked well for me but one. I would to know if someone has found another
https://www.tinmantech.com/html/aero..._flux_core.php
Brazing is not recommended for butt joints, there isn't enough contact area for a proper joint.

Quote:
Originally Posted by bryanwi View Post
I really don't know about panels at all. (And read this and similar threads with interest.)


I have one observation that might be somehow informative.


Ti bicycles are tig welded. I've never seen one done any other way. (Thin walling tubing for weight.) [With argon filling in the tubes, so there is atmo control on both sides of the weld]


Steel bicycles are either brazed with lugs or tig welded. I've never seen an OA welded bicycle.


I don't recall how aluminum frames are done now.


P.S. Weirdly, the only welder I happen to own is a MIG machine, and I pretty much hate mig...


Let's go way OT here.

TIG is pretty much the only way to weld Ti on a production basis - argon filling the tubes, atmosphere controlled "booth" or tented with a garbage bag (ala Gary Fisher).

Brazed, lugged steel frames are the traditional method of bicycle building. Silver brazed is the traditional high end. Steel frames have also been lugless fillet brazed and flash welded - fillet brazed on high end mountain bikes and lots of Schwinns, flash welding for low end stuff and lots of Schwinns.

I'm sure there were OA welded steel frames around at one time or another. However, bicyclists are either a traditional or progressive lot and not very accepting of the middle ground. Consumers are concerned with low price and the low price manufacturers are concerned with low cost and high production rates - generally ruling out OA in those arenas as well. TIG welded frames were pretty much created out of necessity; Steve Garn of BREW says he did his first TIGged frame because he didn't have the proper lug set on hand for a "need it now" job. TIG welded steel frames were once considered a niche item.

Aluminum frames are TIG welded as well - if they aren't lugged and bonded or "screwed and glued".

Aluminum bicycle frames tend to avoid flexibility. The technology and welding skills improved greatly through the eighties and cracking is a lot less common than it used to be. Cannondale set the mark in aluminum with frames like the one used on their R2.8 - you could squeeze the tubes of an R2.8 frame and actually feel a bit of oil canning going on! Gas welding an aluminum bicycle frame (at least as made by Cannondale) would likely have introduced other issues, as, apparently their frames were heat treated after welding in order to get the desired properties.

And now, back to our regularly scheduled program.

I agree with David for a number of reasons, though, as stated early in the thread, there are all kinds of opinions and more than one road will get you home most of the time.

If you have a TIG, by all means, use it. I'm really not very good with the TIG on sheet aluminum and the only TIGs I've tried on ally have been bigger ones where the foot pedal weighs 34 lbs, not the whole unit

That said, a gas rig will get you going on most materials for less than the price of drolling on a TIG -especially and AC/DC unit (the Harbor Freight TIG is a lift start, DC only unit). I have about $800 in my rig with a Henrob and some fairly big tanks. The flux for welding aluminum is getting a bit hard to come by these days. I like Forney #1, but can't find it anywhere.

What I like about gas welding aluminum is that it isn't picky. You can use 1100 rod, strips cut from the base metal or 4043 TIG rod and get good results with any of them.....might not be "textbook proper", but it will work just fine. I find it easier to get a liquid tight seam with gas and lots of "experts" swear that gas welding is still the way to go when building tanks and such due to the "flexibility" (ductility?) of the weld.

TIG probably is easier to learn....but TIG machines were pretty rare in these parts 29 years ago when I started welding. I have noticed that folks who start off with TIG have more trouble with a torch than vice versa. I learned puddle control early on, and that is the key to welding - even MIG (if you can look past the storm of violence to actually see the puddle.

That's my take.
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