I need to rejoin an antique stove base. It's 1/8" thick, maybe 3/16"
in spots. The last time I tried to tig antique thin cast like this it
cracked just from pre-heating cautiously! I'm considering brazing it
to lower the heat input. I wouldn't be opposed to taking a chance
with TIG again though. The only rod I have is 308L, 309L and weldmold
880, which I think is 312 ss. Oh, I also have silicone bronze filler.
The bronze color of brazing rod, or silver ss shouldn't be a problem.
So please chime in. TIG or braze?
As a bit of an aside, I watched a welder at work repair a cast pump housing
using preheat and then using nickel wirefeed (mig) in the cleaned out joint.
The welding involved running an inch of weld here and an inch there until
the area was filled....kept it from getting too hot in one place. Then
some post heat and packed it with insulation to allow it to cool slowly over
a few hours. No cracks and it ground out smoooth.
Thought it was interesting and wanted to share it here.
Splint it with a patch of sheet and bolt or rivet it. Do a job that
looks obvious, but neat.
Cast iron is a pain to weld. Large flat sheets especially so, and cast
iron that gets heated in service afterwards is even worse. Doing
repairs on stoves is one of the worst cases for beginner CI repairs -
they're like exhaust mainfolds, but without the thickness to work
I may be able to get some nickel rod in time. What's the advantage of
nickel? Does it weld better? Anything to help insure sucess is worth
pursuing. But, the bronze will be strong enough given the delicate
nature of the rest of it.
If I get nickel, do I just weld as usual? I assume argon will work?
Nickle is stronger and has less weld contraction.
Grind out the crack so you have clean edges on both sides, but leave
enough of the joint for alignment purposes.
Warm the whole piece gently until a drop of oil smokes (around 500-600
Lay in the nickle with a little heat as possible.
You don't want to melt the base metal, just get it hot enough for the
nickle to stick to it.
Do short stitches, working from both ends of the crack to break up the
On a delicate piece like this don't worry about peening the stitches as
Once welded, pack it in some form of insulation so it cools slowly.
Thanks, I wish I could get away with it! The stove is owned by the
historical society and a friend broke it. I need it to look good.
I'm going to have to 'v' and weld from the back side.
Fortunately, it's the legs so I have some strength needs, but not a
heat cycling issue.
If I may pick your brain some more, why do you advise TIG over
brazing? The foot pedal heat control is one thing that comes to mind,
perhaps the nickel has less contraction than the low-fuming bronze?
Also, is it obvious when the nickel is sticking effectively? I'm
imagining that at the correct heat the nickel will loose its surface
tension and wet the cast iron surface?
Is multi-pass welding risky? It would be nice to build it up a bit.
TIG puts less overall heat into the piece than brazing so you have a
smaller heat affected zone (HAZ).
You have much better control and no flux is used so clean up is quicker.
Once you have the parts joined you can do multipass, just don't get in
to much of a hurry.
Try to keep the whole piece from getting too hot in one spot.
Heat isn't the enemy, it is a heat differential that is the enemy of
cast iron, and cast aluminum and cast bronze for that matter.
Preheating and slow cooling help keep the heat evenly dispersed over
the whole piece.
Okay, I got a line on some nickel TIG filler. (Only one place had it
I've got a Maxstar 200 (thank Earnie for the help on that selection).
Should I use pulse? I'm guessing I should set the amp range at about
110 max (using a pedal)?
My concern with multi-pass and stitch welding too is that I'll be
creating little hot zones here and there that then get re-visited for
another blast. Is this concern unfounded?
I'm thinking about sandblasting, then heating the parts and my steel
shot box in the oven to 500 slowly, then taking the pieces out to the
shop in ceramic fiber insulation, warming up a bit more with a rosebud
or big bertha, then welding, maybe adding a little heat away from the
welded area, then cuddling up in the ceramic fiber again.
If all goes well to that point, what are the chances it's good and not
about to crack like glass?
I also have a bunch and I am willing to sell small quantities.
The pulser is perfect for this as it reduces overall heat input
Once the whole part is hot it is less of a problem.
Easier to just heat them with the rosebud, in place, until a drop of
Moving them around a lot can be a pain.
I welded up an aluminum intake manifold last year for a friend and that
was big enough that I preheated it in the oven and then wrapped it in a
welding blanket .
It had no trouble staying hot enough during the whole weld repair.
SInce I have no idea exactly what kind of cast iron it is, I can't say.
Older castings are usually better made and less likely to crack.
How do you decide the pulse rate and other pulse settings? The Miller
manual doesn't give guidance other than defining the terms and that
rate affects bead apperance; and percentage at peak and peak amperage
The Miller tech. I talked to knew virtually nothing about it other
than that pulse functionality was driven by stainless welding.
I have played with the settings, starting with what you once posted
your machine was set at. I found settings that made the bead smooth
for decorative welding (about 350 pps, don't remember the other
settings and my welder is 40 miles away at the moment). I would guess
that with cast, to minimize heat I'd want less than 50% at peak, maybe
20%, and rate would be as required to make the bead sit well?
Do you think I'll have an issue with curling if I just 'v' the back
and leave the front untouched? It would look the best, and I could
get near 100% penetration...
One of my biggest gripes with the welding manufactures is this very
lack of pulser guidelines.
Basic settings to start with:
50% background amperage
50% Percentage ON time
1.2 pulses per second
Tack weld a strong back across the back of the piece to prevent the
Ernie Leimkuhler wrote in message > One of my biggest
gripes with the welding manufactures is this very
Maybe we should beat it out here!
Wow, 1.2 pps. Why does the Maxstar go to 500!?
For weld *appearance* with mild steel I settled in on
80% background amperage
37% Percentage ON time
350 pulses per second
It works but maybe I'm out in left field.
What's the reasoning behind your recommendations? Especially
confusing to me is, what is affected if it's 1 pps or 500 when the
average (at 50% on time) heat input is the same?
Higher pulse rates, above 4 pps are not used the same way.
A really high pulse rate has the affect of super liquifying the weld
puddle, which makes for very smooth beads.
It is mostly used with autogenous welds, as in no filler added.
It works really well on stainless steel.
Thanks for all the help, Ernie.
I ended up doing it this way:
1). 'v' grooving the cracks except at the ends
2). I pre-heated the smaller broken off pieces then placed a glob of
nickel bead at each end where the crack was left alone, then let them
cool in air.
3). I took the risk of placing a glob of bead at the crack ends on the
main pieces without pre-heat when I realized I'd be better off with a
glob on each half of the crack. I thought I'd probably get away with
it since I wasn't restraining anything from cooling contraction. I
let them cool in air
4). I fitted the pieces back together and hand held them aligned as I
fused the corresponding globs of nickel. The pieces remained aligned
perfectly after cooling in air.
4). I pre-heated the re-assembled pieces then ran a bead along the v
groove. The nickel laid in nicely. Some minimal dripping through the
crack occured where I got a little aggressive. I didn't stitch weld
it since it was only about 3" long anyway. No problem with curling
(after seeing the tack welds didn't budge I didn't expect a
5). I ground off the globs at the ends of the crack and vee'd the
bease metal, then welded it.
6). I re-heated the entire assembly until I just started to see some
red in a dark room, then laid it between two 1 1/2" thick sheets of
ceramic fiber insulation blankets.
7). In the morning I ground them with a stone, then sandblasted to get
some texture blending. When it left the shop the color match was
I'm no fan of welding cast but this was actually fun (barring the fear
and stress). Compaired to brazing this was way better with the
nickel's strong tendancy not to run and the awesome control with the
foot amptrol. Compaired to stick welding it's like the difference
between sex and torture. Thanks again, Ernie, for the good advice.
A couple last questions:
Could I have used a carbide burr to grind the welds? I know some cast
rods are hard as can be, I didn't want to risk trashing a burr.
Have you had experience with the color match in say, a clear coated
part? On the other hand, I wonder if in a rusting situation the
nickel would stand-out?
pre-heating the two smaller broken-off pieces and
How do you balance peak amperage versus on-time and background amps?
It seems like an endless spectrum of possibilites when you think about
upping the peak amperage and lowering the on-time and/or the
background amperage, and vice-versa, etc.
You start with basic concepts and work from there.
The thinner the metal, the more of a Spike pulse you want.
I have yet to find a great use for a soft pulse, but I will get there
Try variations of pulser settings on different materials.
The profusiononline.com online pulse calculators will allow you to
select an average amperage for the pulsing parameters.
There is so little guidance on pulsers in the welding industry that it
is bordering on criminal.
Happy to help
If you used pure nickle filler, then a carbide burr will work fine,
just watch out for the tiny metal slivers.
The only way to get a true color match would be to gas weld it with
cast iron filler rod.
A very involved process.