Welding Tips and Tricks

I bought some Aluminum bronze tig rod after reading about it here.
I am going to tig a heavy piece of cast iron 1 1/4 " thick.weighing 200 lbs
I have welded cast with coated brass rod before but this is a little different.
I have experimented a little and I had decent results.
My question is how hot do I get the parent metal ??
DoI keep more heat on the rod and let it wet the cast or do I try to melt the cast.
In my test when it looked like the cast formed a small puddle I introduced the rod and kept most of the heat on the rod,
Is this the best method.
The piece is 4ft. long,Its the top part of a Brown Boggs shear and weighs approx 200LBS
Because of its size I am cooing to have a problem handling after welding or controlling the cooling process
Could I just do a series of small welds and keep the piece fairly cool to prevent cracks???
I would appreciate any advice

HAS ANYONE TIG WELDED HEAVY CAST WITH ALUMINUM BRONZE ROD
HOW DO I REPLY TO POSTS???

Welcome aboard....

John

Hey,

Welcome to the show. I am going to move this to the welding projects , simply because it could go a number of ways.

Mick.

Hey,

First off, I think you are on slightly the wrong track. I dont think that cast iron, especially very large pieces are welded this way. As you stated, the flux coated bronze rods or bronze rods dipped in flux, are the norm, with an oxy torch. You asked about keeping the heat down, i think that something like this requires the opposite, lots of heat, and very slow cooling, wrapped in a heat proof blanket.

Im sure this raises more questions that it answers, and hopefullly someone with a little more experience will be able to help.

Mick

I'm not very good with Tig braze as I don't do it enough - but usually you heat the parent metal only - not to the point it puddles - just hot enough to dab filler rod on - if you put much heat onto the filler it will burn off most of the zinc - some will anyway & the bigger your gas cover the better- melting the filler onto the parent metal will usually not bond well - Wyatt has a couple of video's on Utube of the process & I think Jody has done as well - I think if I were doing it I'd set the casting on a row of bricks ( fire bricks if you have them ) preheat evenly but not excessively then weld with nickel rods - once welded post heat to try & get uniform temperature then cover with a couple of bags of kiln dried sand poured over it - allow to cool slowly - I've done this method on some large castings & had good results - others will likely have their own preferred method - if the casting is very thick & requires a very wide V prep ( wide preps usually help as the weld is not true fusion but relies on surface bonding ) the cost of nickel is quite high so I've "buttered" the V with one layer of nickel & filled the rest with something cheaper - interesting to hear others opinions on this.
Hope you have success with the repair.

Ace
Thanks for your input
I will let you know how I make out
Bill

I know this is a welding forum, but, sometimes there are better methods. Have you looked at Lock-N-Stitch? I use this method to repair cracked cast iron heads.http://www.locknstitch.com/

Alumike wrote:I know this is a welding forum, but, sometimes there are better methods. Have you looked at Lock-N-Stitch? I use this method to repair cracked cast iron heads.http://www.locknstitch.com/

Will look into it
thanks for the info
Bill

Wkydd1,
Don't know if I will catch you in time. I think you will get various opinions on this and they all could be right. You want to pre-heat to 400 degrees with the alum bronze. My question is if it is a large repair why wouldn't you use 99% nickel rod? I do not have much experience with the alum bronze but I can tell you how I weld cast iron. I had a job where a very large piece of a press had cracked in several places. We made a "hut" out of sheet metal and pre-heated the part to 400 degrees. We did our best to hold 400 until done and heated it back to 400 for post-heat. We wrapped it in insulation inside the hut and haven't had any problems with it. I have had the most luck with this MG 250, although it is VERY expensive, think $1.50ish a rod for 3/32". Above all else for your application I would pre-heat the whole part and post-heat with a very slow cool down.

Superiorwelding wrote:Wkydd1,
Don't know if I will catch you in time. I think you will get various opinions on this and they all could be right. You want to pre-heat to 400 degrees with the alum bronze. My question is if it is a large repair why wouldn't you use 99% nickel rod? I do not have much experience with the alum bronze but I can tell you how I weld cast iron. I had a job where a very large piece of a press had cracked in several places. We made a "hut" out of sheet metal and pre-heated the part to 400 degrees. We did our best to hold 400 until done and heated it back to 400 for post-heat. We wrapped it in insulation inside the hut and haven't had any problems with it. I have had the most luck with this MG 250, although it is VERY expensive, think $1.50ish a rod for 3/32". Above all else for your application I would pre-heat the whole part and post-heat with a very slow cool down.

Thank you for taking time to answer my question
The reason I decided to try the brass rod is that I have gas welded cast with brass rod in the past and had good success.
What got me thinking about using it in this application is because of what I read in this forum.
It seemed to make sense.
I will definitely preheat & cool as you suggested.
I will let you know how I make out when I actually do the weld
Thanks again
Bill

I've done plenty of oxy / acet braze repairs on cast - I'd say it's better suited to smaller / thinner pieces where it's easy to get the whole part hot enough - on a piece as large as you intend to repair I'd go with nickel to butter the prep & then bulk fill - but I've not seen the part & everyone has their own opinion - if you do use Tig braze I've never understood the use of AC & aluminum bronze - it just seems to add a further complication - why not use DC silicon ?