all about welding

[Mike K]

Thanks Phil

Very informative article

You will laugh at this: I have read about carbon arc welding recently. It is a alternative to oxy acetylene welding . You have two carbon rods and a arc that creates the heat . You can braze and solder and even weld steel .

The rods are available on EBAY in various sizes . You use a standard arc welder as the power source .

Are these welders viable ? Have you ever tried the process ?

http://en.wikipedia.org/wiki/Twin_carbon_arc_welding

MIKE

[hrpearce]

Mike I did the oxy welding course at night teck over 30 years ago and as part of the course we some carbon arc and tig welding. I'd take tig over carbon arc any day, my humble opinion.

[Robin Craig]

Noah was a master of carbon arc welding.

TIG is more modern way to go.

All the welding processes have their uses mind you, I still braze items, especially cast repairs, not to be sniffed at. Silver solder has its place also.

Learning to understand the processes and what they can do and why is key to being able to effect a good solid repair.

Am happy to answer questions where I can on welding.

Robin

[Phil Waterman]

I've used both the twin carbon and single carbon torch methods. Used them a lot more before I got the mig welder. Now I use the twin carbon torch primarily for heating steel. Depending on the carbon size and amp setting the heat it can generate is impressive.

Prior to getting a mig welder I did a lot of single carbon brazing of sheet metal seams. I'd just put a carbon rod in the stinger of the stick welder ground the work with the clamp, put the tip of the brazing rod (no flux) on the seam and then stroke the arc on the tip of the brazing rod and puddle and flow the bronze. I could braze better than I could weld sheet metal with the stick welder.

Interestingly there is a carbon rod attachment for the mig welder so that you can spot heat for shrinking dents.

This weekend was first time I got to try and compare different welders side by side. I think everybody walked away at the end of the day knowing more about their own machine and how to get more out of it. The guys who didn't have welders who are thinking about get one got the most out it.

This type of event would be a good idea for any MV (antique car) club to host.

Cheers Phil

[Mike K]

Originally Posted by Phil Waterman

I've used both the twin carbon and single carbon torch methods. Used them a lot more before I got the mig welder. Now I use the twin carbon torch primarily for heating steel. Depending on the carbon size and amp setting the heat it can generate is impressive.



Cheers Phil

Interesting . I have read that it's a very handy process for brazing broken cast iron bits together . The twin rod setup is best with a AC source they say . With DC, one rod tends to burn away faster than the other .

Mike

[Robin Craig]

Not wishing to teach Grandma how to suck eggs you understand . . . .

Briefly some cast snippets for you guys.

The basic problem with cast ferrous objects is that when welded the weld material deposited shrinks, as all metals do as they cool, the shrinking speed is faster than the cast and hence the weld cracks.

That is the simplified basic problem.

Basic remedies are to pre-heat the subject, keeping heat on if you can during welding. If it is just a crack then stop holes must be drilled at the end of the cracks. If it is two or more lumps / pieces then making a bevel from both sides helps in preparing the joint.

Also in preparation drilling either side of the break and installing knurled pins into holes making an interference fit helps alignment and strength also.

Preparing a cooling bath of fine material such as sand and post heat should be considered.

When using MIG welding I have had great experiences with a very slow jive of pre heat, weld a 1/4 inch, heat and peen simultaneously, heat and weld and peen weld and repeat and nauseum. The peening stretches the deposited material and stops the cracking. Once the joint is closed, backgrind the weld and weld over again. Failure to peen at any time is direct path to a cracked weld.

If you have no patience dont start.

I have used mild steel MIG wire, high nickel stick rods, done it with TIG and bared stick nickel rods, done it with stainless wire or rods.

Brazing is much easier.

Understanding why the part broke in the first place is the critical step most fail to understand. Often it is just abuse or the same spelled differently ie too much power.

If it is a classic flaw in the design of the casting you will have to remedy that first.

Brazing is brilliant for making a new surface for machining and bearing installation when the old one has worn out the cast as it thrashed around.

Because brazing is softer, home made mills in the drill press and dremel tool fondling has been known to make things work. Brazing is so kind on the restoration as it can easily be worked and blended in and after paint is hard to spot.

Silver solder is remarkably strong and is great for small item repair.

Cleanliness is a vital ingredient in any of the above, welding detests hydro carbons be they paint, grease, oil or fuel.

If you want a cheap and easy workshop dye penetrant for cracks my preferred route is finely shaved soap stone and dyed diesel fuel.

Clean and dry the suspected area. Using Q tip or larger dab dyed diesel alog or around the crack. Dry by wiping surface clean thoroughly, do not apply heat.

Gently lightly dust crack area with soap stone dust. Watch dust turn pink as fuel gets drawn out of crack into the dust. You will be amazed at the results.

Have fun

Glad to pass on what others have taught me.

R

[RHClarke]

As a new "welder" I am amazed at how much I need to learn about this "art".

[maple_leaf_eh]

Originally Posted by Robin Craig

Not wishing to teach Grandma how to suck eggs you understand . . . .

Brazing is much easier.

Understanding why the part broke in the first place is the critical step most fail to understand. Often it is just abuse or the same spelled differently ie too much power.

If it is a classic flaw in the design of the casting you will have to remedy that first.

Brazing is brilliant for making a new surface for machining and bearing installation when the old one has worn out the cast as it thrashed around.

Because brazing is softer, home made mills in the drill press and dremel tool fondling has been known to make things work. Brazing is so kind on the restoration as it can easily be worked and blended in and after paint is hard to spot. ...

Glad to pass on what others have taught me.

R

Hmmm? I have a Spanish FR7 rifle with a $hit trigger pull. A nub on the top of the trigger rotates on the bottom of the receiver. The Spanish gendarme must have dry fired 25,000 times, because there is depression worn in the steel. I've often wondered what I could do about that problem. Now I see an option.