[TheForge] Welding cast wood stove baffle

Mon Apr 8 20:33:01 2002

        Michael,  I don't believe you are a bad welder, but may have run
into one of those stove parts that are a nightmare.
        The thing with a baffle is it is exposed directly to the fire and
there fore it not only gets intense heats, but it also gets all the
impurities in the smoke that will fill the pours of the casting.  When a
baffle is warped, cracked and looks like it is blistering away, I have never
had much success other than to apply a mechanical patch with stainless
bolts, and even that has it's limits.
        There are four types of "cast iron" from what I under stand.   There
are as many if not more rods for arc or stick welding this material, as the
one you mention is 99% nickle, I also know they sell an alloy with 55%, and
another with 2%.   There are even rods with no nickle in them for welding
cast.   These various amounts of nickle pretty much have to do with
machinability when you are done.  They also have different fluxing agents as
the cast that is exposed to oils, grease, pitch, etc.  as in a wood planner,
or machine like a power hammer.  This is something that takes persistence to
keep preheating and removing the impurities to get a chance at the weld
taking a hold.
        I have also repaired cast by brazing with brass rod and a torch, but
this is something that once failed and I had a miserable time redoing it
with arc welding after - in fact I never really got it right, but it held up
so far.  There were parts that still had perosities where the brass in the
pores blew the weld puddle out.   Brass is a good repair on most cast items,
but the color match leaves alot to be desired.......unless your good and can
just leave a wicked in seam of brass in the hair line crack.
        Some have used Oxy/Acet to repair cast, and others use tig to repair
cast.  I have tried the tig rod, but not the Oxy/Acet.   The tig rod is
slick as there is little clean up, but the repair takes forever to complete
as it is a slow process.
        Now heating is everything in cast welding.  In fact some repairs if
you clamp them down and don't let them move or expand and contract willingly
will make your welds fail.  I usually use a heat sink or something that I
can preheat the item and the plate or block to hold the heat, while I do the
stitch welding(never attempt to just run across a cast panel in a 12" bead
of weld.........there will be way too much heat delivered all at once and
the contraction along the area will make for tension and a break next to the
weld.  So cleaning, V grinding, preheat, wire brushing, welding, and post
heating or using a heat stay or block will help with your repairs.  On top
of stitch welding you are also recommended to stress relieve the weld bead
by working it with a chipping hammer by tapping......not pounding.
        The main reason I haven't had much interest in the torch work is
folks are usually getting me to do large industrial castings like planner
frames, and sawmill equipment when the call comes for repair............and
trying to heat a planner all up equally to get a good torch repair is a
major chore.
        One of the slickest methods for repairing cast is a powder torch
which actually shoots the cast powder thru a flame of a special Oxy/ Acet
torch made for this type of work.  They are amazing as you do the preheat,
then shoot the material and if things get to hot you back away, it cools,
you have at it again, and I've actually seen a guy weld up a 3/4" hole in a
Mack Truck exhaust system with this method.  Way cool, but the torch is
about 700-1150 and the nickle powder is about $50-100 for a small container.
(read 2-3 repairs - or one large one)
        Another thing to mention is making sure it is cast.......  if it is
Vermont Castings the odds are it is cast - it's probably just too dam dirty
to get it to hold.  Nickle needs a clean surface. When drilling cast it will
usually powder, with cast steel it will usually send slivers off the end of
the bit, and with steel you get the usual spiral feeding off the
tip(providing the drill is sharp).
        So there are a few things to watch for, and practice is one of the
best things for improving.

Ralph


----- Original Message -----
From: "Michael Boettcher" <[email protected]>
To: <[email protected]>
Sent: Monday, April 08, 2002 11:24 AM
Subject: [TheForge] Welding cast wood stove baffle


> I tried welding a cast iron wood stove baffle this weekend, and had a
> complete failure.  I preheated, and used a nickle rod ("premium 99 Nickle
> electrode).  I've used it in the past, and have had great results.  This
> time, the nickle ran away from the base metal, and the base metal was
eaten
> away.
>
> I tried colder, more preheat, low amps, high amps.  Nothing seemed to
help.
>
> Casting is from  a Vermont Castings stove.
>
> Am I that bad a welder, or is there something about this particular metal?
>
> Thanks,
>
> Michael
> Madison, WI
>
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