Welding cast iron

[Smouser]

Hi,

I have been trying to repair a few cast iron drill tables and vices.

I have been using NI-CI 2mm rods with varying success. Also some cast iron seem to weld better than others.

I have bee using the 'cold weld' method doing short runs to keep the heat down.

Can anybody explain why these holes/craters sometimes appear? It is driving me insane.

 

[tom2207]

dirt /impurities boiling out , keep drilling them out and rewelding and one time they will not be there ,,, or drill them and then braze the holes.
Cast just isnt handy to weld , high nickle rods and patience , pre heat and post heat ,,, and patience.

 

[Tigman]

Cast iron is porous , sometimes oil gets in the break , a bit of preheat may help , also get lots paint away from the weld area !

 

[Smouser]

Thanks to you both. I will give it a try again.

I was a bit lazy with the paint stripping tonight on that vice (did not want to run the grinder after 2000hrs).

 

[gt6s]

That is caused by air bubbles in the casting grind out fill with new weld.

 

[Mikes]

A lot depends on the quality of the cast iron to begin with. Old british cast iron is the best to weld (will have a nice grey uniform texture). A lot of Chinese and Indian cast iron will be mottled in colour and resemble an Aero bar along the break and is not as easy to weld as full of impurities. Dissimilar metal rods are good for taking the pieces together but have to be very careful not to put too much on at a time as can induce cracking.

 

[minimutly]

Even if the parent iron is good, if you weld it cold, the weld metal cools and shrinks so will crack. The answer to that is to peen the weld with a small ball pein hammer as it cools.

 

[Smouser]

I was making progress, until my welding cable broke off just after the crimp.

I need to get some heavy duty crimps somewhere tomorrow and recrimp the thing.

I am building a corner up of a vice, that in its past life had a run in with a mill bit.

To be continued....

 

[Smouser]

As usual, I forgot to take a good before photo. The photo below is one I took for another reason but at least you can see some of the damage.

This is the after

Not perfect but I am happy enough with the result.

 

[zeppelin builder]

any thing that gasses gives pores eg
paint ,oil ,water

 

[Robert Mullins]

With the porosity in the weld deposit, you need to watch the bead as you're laying it, if/when you see the blow hole appear, step back, stop and fill it and continue as before: as mentioned before, the quality of the material, contamination of the metal will cause welding issues;
The tensile strength of the weld metal is much greater than the cast iron, therefore when preparing the butt, you only need a 2/3 the thickness of parent material to gain adequate repair strength: over welding creates more contraction and cracking

 

[Thederustinator]

There are 4 types of cast iron:-
Grey Cast Iron.
White Cast Iron.
Ductile Cast Iron.
Malleable Cast Iron.
The holes are the carbon used in converting Iron from Iron ore. These bubbles are formed by excess carbon not mixing properly. The cheaper the item, the poorer the casting and the more inclusions you get. To get a decent weld with cast Iron or Aluminium, heat it first to burn off inclusions in the prepared surface in a barbeque or wood fire, and this also helps to stop cracking when it cools after welding.

This explains more https://www.metalsupermarkets.com/the-4-types-of-cast-iron/

and

Cast iron - Wikipedia

en.wikipedia.org

 

[Smouser]

I have done some more cast iron welding. It remains a mystery to me

Sometimes it seems to weld ok, other times it is a disaster.

Anyway, here are some photos of a Meddings pillar drill stand/footplate or whatever it is called.

The damage

For the crack, I used a cutting disc on a grinder and cut into the crack about halfway of the thickness of the cast iron. I then welded it up and did the same from the bottom.

This is the result after filling it down

Not too good, but not too bad.

I then used a grinder to cut away some of the angled breaks in the cast iron.

Got some 10mm steel plate which was about the right thickness and tacked it up.

 

[Smouser]

Another view

Adding the 'top plate' of the repair

I managed to get one good better bead on the underside of the repair.

Almost done

Using a Meddings to fix a Meddings!

The final result

Happy enough with that, in my opinion, it is much better than what I started out with.
It needs a proper clean and then it is ready for paint.

 

[Mikes]

Nicely done and well worth the effort to make the drill useable.

 

[Smouser]

The newest cast iron welding practice was on an Elliott Progress 3A pillar drill table.

It is pretty heavy, coming in at about 105kg.

It was not in a too a bad condition.

I heated it up with a blowtorch to draw some of the old oil out of the cast iron.

I once again had some blow holes so I drilled them out and tried again.

The final result after many hours hand filing the welds flat (to try and ensure the table stay as flat as possible).

I could possible make some very minor improvements to some areas but I don't think the time and effort is worth it.

The centre hole will be cleaned up with a drill once the table is back on the drill one day.

 

[brightspark]

The newest cast iron welding practice was on an Elliott Progress 3A pillar drill table.

It is pretty heavy, coming in at about 105kg.

It was not in a too a bad condition.
View attachment 359981

I heated it up with a blowtorch to draw some of the old oil out of the cast iron.
View attachment 359982

View attachment 359983
View attachment 359984

View attachment 359985

I once again had some blow holes so I drilled them out and tried again.
View attachment 359986

View attachment 359987

The final result after many hours hand filing the welds flat (to try and ensure the table stay as flat as possible).
View attachment 359988
I could possible make some very minor improvements to some areas but I don't think the time and effort is worth it.

The centre hole will be cleaned up with a drill once the table is back on the drill one day.

best die grinding the hole round at 1st. a drill bit will chatter like hell and run off. a nice end mill would be good

 

[Smouser]

best die grinding the hole round at 1st. a drill bit will chatter like hell and run off. a nice end mill would be good

Thanks for the tip!
I don't have any die grinding bits but I will get some.

I don't have a milling machine, unless you mean I use the end mill in something else?

 

[brightspark]

nice repairs by the way

 

[premmington]

Lincoln RepTecCast MMA rods "graphite-coated stick electrode with a nickel iron core for cold welding of cast iron, malleable cast iron and joint welding to steel."


or TIG brazing.

Strength is about the same at 300nM 2 (squared)...