Cast Iron welding Sticks

[WALLACEParticipant @wallace]

[WALLACEParticipant @wallace]

 

I have in my junk box a very ill-used Nippy vice that i’d like to bring back to its former glory . . as the base of it looks like a lump of cheese.

 

So  – the question is – can I just scrape the flux coating of a stick designed for a MMA welder and use them with a TIG ??  

 

thanks

 

WALLACE.

 

 

[Clive FosterParticipant @clivefoster55965]

Just use the rod as is, inverter welder is best but the usual buzz box will get the deed done.

Trick is to use a small rod on the minimum current that will work to build a layer of weld metal on the cast iron before filling with an appropriate size rod.  Two or three thin layers should be fine.  Best to tap the weld area s it cools which offsets some of the contraction stresses.  Its a sort of peening which tends to expand the new metal.

 

Thin layer, minimum current, reduces and carbon migration into the weld around the joint area.  Too much carbon migration plus fast cooling adds up to a joint is what is effectively fully hard carbon steel.  Basically a crack waiting to happen.  The thin layering method minimised the thickness and amount of carbon migration and makes the join proper in weld metal which is designed not to go brittle as it cools.

 

Obviously you don’t try this sort of thing on heavily loaded structures or anything tension loaded.

 

Clive 

[Steam of SteelParticipant @steamofsteel]

I would agree with Clive but like to add that if you pre heat the component to about 150 to 200°C, I have a small domestic oven for this sort of job,  it will help. After the welding return the component to the oven and leave it to cool slowly.

 

Garry 

[ChrisHParticipant @chrish]

The pre-heating is very important.  If you don’t have a small domestic oven use a flame but play it very carefully all over the item.  The idea is to heat it evenly and slowly without hot spots.  

 

Then when welded wrap it up in an insulating layer of whatever blanket/s you have to enable it to very slowly cool.

[WALLACEParticipant @wallace]

Looks like the oven then. Good job I don’t have to ask Domestic Management.   

 

W.

 

 

[Steam of SteelParticipant @steamofsteel]

Just be aware that when you use the oven, the smell ist relatively intensive especially if there is some oil grease or paint left on the component.  If your workshop is within the house you may get into trouble with your domestic management good draft free venntilation is essential.

 

[Clive FosterParticipant @clivefoster55965]

IMHO the need for pre-heat and slow post weld cooling on simple cast iron repairs is frequently overstated.  It is of course vital on large and stressed repairs but, frankly, I don’t think the amateur and inexperienced should get involved with any job that needs pre-heat.  Use it by all means if you are comfortable as it does help to produce a good job quicker but the cold, layering technique I outlined is / was an accepted textbook method for smaller jobs.  When I raised the point with an experienced welder of cast iron he said “You’d certainly do a better job that way but its too slow for a professional like me.”.  Meaning of course that carefully putting on thin layers with minimal heat input was well within my limited skills but coping with a hot lump of cast-iron whilst simultaneously getting the right weld bead thicknesses in the right time was not.  He told me that pre-heat was only a small part of a proper job and it wasn’t of great value unless you got the rest right too.

 

I certainly wouldn’t bother for “cheese repairs” or fixing chuck collision scars on a top slide and similar jobs.  I recently built up the top slide on my Pratt & Whitney B restoration project and felt that a harder surface to the tool post mount area would be desirable so I used more current and 10 gauge rods.  Worked a treat as the surface is now just too hard to file so I must have got the carbon migration about right.  Largest job I’ve ever done cold was to stitch an old 15″ Harrison apron back together after it had fractured into 4 pieces when it fell over.  Through 2 shaft holes too.  Hard work,  I did have to grind out and re-do a few cracks, but its held up just fine for 10 years now.  Could do better now.

 

Clive 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, using MMA rods for cast iron or any other metal with TIG is not really a good idea. MMA rods do not have the correct types or amounts of deoxidents to produce a truely sound weld in TIG welding, although you may get a satisfactory result don’t trust your life on it.. MMA rods are alloy rods and there are a few differant types depending on what you are actually welding, pre-heating to any real degree is not really needed as many of them are designed to weld cast iron cold. The shape and design of the casting will make the techniques for welding the deciding factor, and as has been stateted peening each run will help reduce contractional stresses. You may even be suprised to learn that there is a technique where you quench each run straight away, the runs being relativly short. This is used in some cast iron compositions to reduce carbon migration to a minimum, to prevent hardness cracking. The type of cast iron will make all the differance of course, mallable cast iron being one of the easyest. Real cast iron welding is done with Oxy-Acetylene, which does need preheating and very often in the right areas. It would most likely need post heating as well and slow cooling in a hot box. Oxy-Acetylene welding of cast iron is quite skillfull to be successfull and is not for the faint hearted.

Regards Nick.

[Ray LyonsParticipant @raylyons29267]

I picked up an all “singing and dancing” milling vice at a car boot sale recently. (I mean it swivelles in all directions) It was cheap at £25 because one of the securing lugs on the base was missing. The seller said that it could not be welded but it could be repaired by carefully  bolting a piece of plate on the bottom. I had a piece of scrap casting which was just the right thickness and cut several pieces for test welding.  The thickness was about 3/8″ and I V ground the sections to be welded.  Using the stick welder on DC current negative earth, I did some passes,gradually increasing the amps to 90 where I obtained a reasonable fillet. The test pieces were then placed in the corner of a concrete step (very technical) and hit with a lump hammer to breaking point. In each case the parent metal broke leaving the weld intact. One piece I kept to test in the milling machine and had no problem cutting off the weld to a nice level surface.

I then went on to weld the vice and then mill to match the undamaged side. 

As a total amateur, I feel that so far it is an achievement but how long it will last I don’t know.  

[Simon LeeParticipant @simonlee19625]

th

[Simon LeeParticipant @simonlee19625]

My Dad worked as a welder for the Pulsometer Co in Reading back in the Sixties. One of the regular jobs was to weld cast iron pump sections together, some of which were large enough to stand inside. They were also of very variable section thickness which made contraction fracture a very real (and very expensive) possibility. To avoid this they used a combination of pre-heating and edge preparation. The joint faces were machined to give a deep vee and then the fitters would tap the veed edges and screw in studs made of “dead mild” steel in an interlocking pattern. The parts were assembled and the whole affair brought up to working temperature. Father and his mate would then weld round the joint with 1/2″ nickel/iron powder rods. The mild steel studs melted into the weld pool and made a more malleable joint which would give a little under the contraction stresses. The welded assembly was “let down” to room temperature very slowly, sometimes the piece was re heated if the charge hand felt it was needed. Dad remembers that the heat and sweat were tremendous and necessitated regular visits to the “Black Boy” pub around the corner- no-one complained, it was accepted as normal and necessary!

[Ian S CParticipant @iansc]

Watched a bloke doing cast iron repair welds at a local A&Pshow (agricultural & pastral), he was selling a different type of oxy- acetylene torch, it used the gasses at half normal pressure. He was using bits of broken cast iron scrap as filler. He went on to do the same with aluminium castings. The welds seemed sound, though no testing was done. Not on topic, but what can be done, don’t know if something similar could be done with a carbon arc torch. Ian S C

[russellParticipant @russell]

that sounds like the dillon/henrob torch. It’s claimed to havea very hot, very fine flame that allows the weld to be made with very localised heating, hence no need to preheat etc. Also used to repair dies for injection moulding.

regards

russell

[jomacParticipant @jomac]

hi , cast iron welds need pre heat, plus as mentioned before tap weld area with a small hammer, if you dont have a cool down oven, stick the job into a bag of lime, if you dont have that, use dry cement, Iv’e done welds with a stick welder and use the stitch method of welding, it lessens the stresses, came back next day to get job out of the lime container, and it was still warm, Some welding sticks such as Eutectic are excellent, BUT are expensive, even for a pack of six. but that was some years ago.

John Holloway

PS made a couple of indexable tool holders today, I had to go inside next to air conditioner a few times as the temp even in the insulated workshop was over 32 degrees.

[Richard ParsonsParticipant @richardparsons61721]

Jomac lucky devil it is -21 outside here (Hungary)

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