all about welding

[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".

[Phil Waterman]

All I can say is Practice, practice, practice, I have to force myself every time I have welding to do on a project to stop and practice before I try to do the welding on the "finished" part. I've found that if I take the time to get some scrap steel out of the same thickness of what I want to weld and practice until I can produce a good smooth weld it actually takes less time than grinding off the crappy first weld.

For me I need to run 1-2 feet of seam weld as practice or someplace where it won't show before I can produce a weld that I want other people to see.

But then again on CMPs they didn't clean off the splatter,the underside of my HUP looks like they held a welding class while they were fabricating it, there are some really crude welds. But remember this was mostly done with stick welders, none auto darkening helmets and somebody screaming hurry up we have another 50 to get done on this shift.

We have some guys in the club who are real well trained experience welders for them it doesn't matter if they haven't touched a torch in a year they pick it up and produce perfect welds.

Cheers Phil

[Phil Waterman]

To produce a crack free weld in cast iron is an art. And is really all about pre-heating from my limited experience. The question is how much pre-heating and to what temperature.

Once watch and old timer weld up a Model A Fords head that had cracks in the water jacket from freezing. He cleaned it up, dumped 20-25 lbs of charcoal in the barbecue grill put the head on the grill and lit the charcoal. He let the whole thing sit their until the coals were all nice a hot then with the thing still on the grill he took a stick welder, with what I suppose were the correct rods for cast iron, and started to weld up all the cracks. As he weld a few new ones showed up and he welded those as well. Then he said just leave it on the grill until its cold. My brother had that Model A for about 20 years after that no leaks, people would ask about the funny looking welds on the head.

Cheers

[Alex Blair (RIP)]

Originally Posted by Phil Waterman

To produce a crack free weld in cast iron is an art. And is really all about pre-heating from my limited experience. The question is how much pre-heating and to what temperature.

Once watch and old timer weld up a Model A Fords head that had cracks in the water jacket from freezing. He cleaned it up, dumped 20-25 lbs of charcoal in the barbecue grill put the head on the grill and lit the charcoal. He let the whole thing sit their until the coals were all nice a hot then with the thing still on the grill he took a stick welder, with what I suppose were the correct rods for cast iron, and started to weld up all the cracks. As he weld a few new ones showed up and he welded those as well. Then he said just leave it on the grill until its cold. My brother had that Model A for about 20 years after that no leaks, people would ask about the funny looking welds on the head.

Cheers

Phil..
The old lad had it right..I used 2 hibachi BBQ's as a forge with a pilot line of oxygen out of the oxy-acetlyne into the bottom of it..Get that head red hot and stick weld it with a cast iron rod..then let it cool off to cold and then re-machine IT..I THOUGHT YOU WOULD TRY IT WITH THE CRACKED HEAD WHEN YOU GET YOUR NEW ONE..CLEAN UP THE CRACK WITH A DREMEL AND
give it a go..

[Mike K]

Can I ask Phil or Robin or anyone:

I am making new outer fender or wing panels for my 1950 land rover . In order to get the correct radius on the top corner I have to weld in a section, rather than make the panel in one big lump.

The metal is 18 gauge aluminium . I read that its possible and easy to mig weld thin alum. with ER 4043 wire , but it has to be .3 size wire. After googling , I found some suppliers in the USA , but none here . I can only get .9 wire here .

And, dont know how .3 wire will work in my machine , its rather thin wire , will it feed ok ?

BTW they recommend pure Argon for shielding , not CO2 mix with Argon
Mike

[Alex Blair (RIP)]

Originally Posted by Mike Kelly

Can I ask Phil or Robin or anyone:

I am making new outer fender or wing panels for my 1950 land rover . In order to get the correct radius on the top corner I have to weld in a section, rather than make the panel in one big lump.

The metal is 18 gauge aluminium . I read that its possible and easy to mig weld thin alum. with ER 4043 wire , but it has to be .3 size wire. After googling , I found some suppliers in the USA , but none here . I can only get .9 wire here .

And, dont know how .3 wire will work in my machine , its rather thin wire , will it feed ok ?

BTW they recommend pure Argon for shielding , not CO2 mix with Argon
Mike

Mike

When welding aluminum you use a heli-arc machine..with a foot pedal volt/amp control..
Auto wire feed and you can butt weld two pieces of aircraft aluminum skin as fast as you can move your hand with the stinger..
And look like you have been welding for years..
I used to go to the metal shop on the hanger line and play with the heli-arc welder with scrap aluminum..with a few minutes instruction you would look like a pro..Helium is the shielding gas..
Check out your local air craft repair facilities..
Of course I had the whole RCAF aircraft metal shop to play in...
Heli-arc was the old timers terminology..TIG welding is what it is called now..
Here is a good video of the TIG foot pedal operation..the more you press the hotter it gets..You can by lightly pressing on the foot pedal butt weld your thin aluminum sheet with out filler rod with a little practice.
Enjoy your welding..]
http://www.youtube.com/watch?v=QpPQNq7Y-WY&NR=1
http://www.youtube.com/watch?v=R8B3q...feature=relmfu
http://www.youtube.com/watch?v=Gvk8r...eature=related
http://www.youtube.com/watch?v=VEEpi...eature=related

[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.