The gent offering a rod assortment on ebay got me thinking...Ive only
made repairs with brazing rod on cast iron, worked pretty well. But I
know that there are electrical welding rods for cast iron that can be
used on buzz boxes and other small home AC-DC welders such as the
Lincolns etc.
Anyone have a preference for any particular rod for repair of cast
iron stuff? For example..building up the corner of a lathe compound
or a cracked apron, or a busted bandsaw wheel..that sort of thing.
Gunner
'If you own a gun and have a swimming pool in the yard, the swimming
pool is almost 100 times more likely to kill a child than the gun is.'"
Steven Levitt, UOC prof.
I haven't done anything too impressive with it, but I've used 99% nickel to fix
older castings. Works well, just peen as it cools. Repaired a DP belt guard
pretty well this way.
GTO(John)
>The gent offering a rod assortment on ebay got me thinking...Ive only
>made repairs with brazing rod on cast iron, worked pretty well. But I
>know that there are electrical welding rods for cast iron that can be
>used on buzz boxes and other small home AC-DC welders such as the >Lincolns etc.
>
>Anyone have a preference for any particular rod for repair of cast
>iron stuff? For example..building up the corner of a lathe compound
>or a cracked apron, or a busted bandsaw wheel..that sort of thing. >
>Gunner
>
> 'If you own a gun and have a swimming pool in the yard, the swimming
>pool is almost 100 times more likely to kill a child than the gun is.'"
> Steven Levitt, UOC prof.
they sell ni rod for cast iron but i like to use stainless with a hi nickle
content. saw blade wheels do not weld well, you definatly need to preheat the
wheels or they will crack in different places.
When repairing cast iron the acceptable rod to use is a ni-rod which is
nickel. This will produce a machineable deposit. Other rods are used but
you risk a hard deposit that is not machineable. They are not worth using
for the slight saving in price.
I have had good luck repairing with brazing rod however it is labour
intensive and you have to do a lot of preheat and post heat.
With ni-rod you can stitch if the casting is large and intricate by
running no more than an inch at a time and peening the bead as it cools then
waiting until the casting cools to room temp before putting in another inch
stitch.
The other way is to follow preheat and post heat similar to brazing.
Building up the edge of a compound is not difficult. Once you are
involved with things like spoked wheels the shrinkage stresses can easily
result in cracking after the repair is done and it is cooling.
The last year of my apprenticeship the owner of the shop would not allow
any cast iron repirs done with Ni-rod. Everything had to be brazed. By the
time I left I was pretty good at brazing cast iron and started to prefer it
over stick welding.
With cast iron procedure is everything no matter which process you use.
Randy
Many thanks Ernie. Standard Preheat, post heat and peening I assume?
Gunner
'If you own a gun and have a swimming pool in the yard, the swimming
pool is almost 100 times more likely to kill a child than the gun is.'"
Steven Levitt, UOC prof.
The NassauRockmount "Jupiter A/AAA" series is similar to the
Certainium 889 rod if I recall correctly. They are a good general
purpose 55% nickel rod with good welding characteristics for almost
all types of weldable cast iron. Excellent on dirty or oily cast
iron.
The "Jupiter B/BBB" series is 99% nickel. A little more sensitive to
the condition of the base material being welded, but should be more
machinable. The BBB version has a non-conductive flux and won't side
arc... handy for getting into tight spots. I was always able to weld
multiple passes of B/BBB over it's own slag without porosity problems.
Yes - preheat, peen, and post heat would be helpful I should think.
Keep in mind that some grades and types of cast simply aren't
weldable, and brazing would be required (but that represents an
entirely different set of problems).
Dave
Randy Zimmerman wrote:(clip) The last year of my apprenticeship the owner of
the shop would not allow any cast iron repirs done with Ni-rod. Everything
had to be brazed. (clip)
^^^^^^^^^^^^
I am interested to know what your boss's objection was to stick welding CI.
I am a NOVICE welder with decades of experience, and I have recently
discovered how easy it is to stick weld CI with the right rod. I didn't
even know you're supposed to peen, and yet everything I have done has been
OK.
Old Peter was a product of the Thirties and had his own way of doing
things. He did cold stitching on larger casting such as engine blocks. It
is time consuming but there is not heat involved. There are still outfits
repairing using that method. I imagine previous welders he had working for
him had screwed up when arc welding cast and he blamed the procedure rather
than the operator.
Brazing is a reliable repair in that you see what you get. If you are
not getting a good bond to the cast iron it is very apparent as you lay the
filler rod in. The brazing alloy is a good match on strength with cast
iron.
The problem with arc welding cast iron is that people tend to cheat by
rushing the job or having inadequate preheat before they start. If you are
doing short welds and peening without any preheat you have to be patient.
People often put a few short welds in and peen. Then they get impatient
rationalizing that the repair is cold enough for another weld. "Hey! It
wasn't red anymore and my arm hurts from all the peening"
When Peter went on his hunting holidays I would arc weld cast iron
fractures for farmers coming in. It was cheaper than brazing because I
would only charge for the welding and peening. It would take all day to do
the job but I would only spend fifteen minutes total doing the repair. I
would go over and run a small bead, peen and go away to my other jobs.
The idea of peening is to stretch the weld bead as it cools. That
counteracts against the shrinkage forces. With mild steel shrinkage forces
bend or stretch the steel but cast iron does not stretch or bend very much
before it cracks.
The design of casting always takes into account how the piece will cool
in the sand. Often castings have unusual heavy sections to cause the
casting to solidify and cool evenly. If casting is heavy and massive at
both ends with a small section connecting the casting will crack and never
see full production. When welding cast iron one has to take this concept
into consideration.
Randy
Everything
Gunner,
By coincidence I tackled my first cast iron welding project today. My
inept twin broke the motor mount on an antique woodcutting bandsaw
while unloading it.
I used 99% nickel rod and it "seemed" to weld very nicely but I think
it's a similar case to MIG welding, where it's easy to make a pretty
bead, but a pretty bead doesn't necessarily mean a strong weld. I
tacked it in a couple places first for alignment. I didn't get it
quite right, and in tapping it lightly to line up the parts, the cast
iron surrounding the tacks was very brittle and broke. I think that
is the weak link in welding cast iron, the stuff is not very flexible!
Clearly, pre-heating and peening is important, and I think also slow
cooling.
The books I have all mentioned the importance of removing all casting
skin and vee-ing the crack or parts.
Bob
I won't even claim to be a knowledeable welder compared to those more
formally educated in the art, but I've had some pretty good results on cast
iron pumps and such by preheating with a rosebud, then DC tigwelding using
nickel stick rod with the flux ground off, for filler. After welding, warmed
again with rosebud and let benchcool. Also did the same process using a tig
rod someone gave me called Ever-dur or some such. (Silicon based, I think).
Also tigged up the holes someone had drilled in the body of a '40 Ford truck
I was street rodding with it.. Stuff puddles like putty and is very
manageable in controlling droop and fallout. Stuff tigs well on galvanized
steel, too. Just don't breathe while welding. :)
RJ
Preheating and post-cooling are critical on things like a spoked wheel, such
as Gunner was contemplating, but really not very necessary if the part can
cool without developing stresses. If you are welding a spoke, the rest of
the wheel prevents the spoke from shrinking as it cools, so it goes into
tension. As we all know, CI has practically no tensile strength (great in
compression, though), so it will crack. If you are welding the broken lug
on a bandsaw base, it can cool without stress, so there's not too much to
worry about.
Funny, I was under the impression it often had 30 to 60kSI, comparable
to mild steel. Now, plastic deformation, it hasn't...
Tim
--
"That's for the courts to decide." - Homer Simpson
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