Welding Decorative Cast Iron Post Cap

If they are dead soft annealed grey iron then your MIG will work OK. If they are brittle white cast iron then the nickle rod would be better. I have run into both types.

I have used dual sheild mig on the castings with good effect. Les

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No problem. I weld those all the time. It will work just fine. Just keep the puddle on the steel post, and let it wash up to the cast iron. They do make drive on steel caps, and drive in plastic caps.

I am out the door to make 24' of 7' high fence that will have one atop every post.

Steve

FYI, dual shield is actually flux core not mig

Tom

I took a file to one today and they "seemed" as soft as mild steel.

SteveB wrote:

Yes, I'm using the plastic push in ones everywhere except the corners where I'm using the cast iron ball style.

Once again, thanks guys.

Not sure what the difference is. I have welded on hundreds of picket points and cast iron decorations. Most welded on okay, and a few had a foamy porous weld. All were acceptable, and required no special welding process. It probably wouldn't have pleased a metallurgist, but they were good looking as a finished product. Provided you ground them down and put the right amount of paint on them, that is. ;-)

STeve

Just go ahead and MIG the cap. Been doing it that way for years. All the cap is going to do is to sit on the post and no stress or other stuff.. Too expensive for nickel and preheat is not needed and would add too much to the cost of fabing.

ditto

I have done a fair amount of fence work and had great difficulty trying to weld the cast iron caps onto the mild steel posts. I have only had very limited success using mig and regular mild steel wire. I have tried various setting without experiencing consistant positive results. The castings are probably at the very bottom of quality metalurgically speaking. The main problem I have is trying to get the weld puddle to actually melt/bond with the cast iron. When the weld cools and I test the weld by hitting the cap with a hammer, it usually fractures easily at the weld interface between the cast iron and the weld filler metal. I will read this thread with interest. rick

Your "test method" seems a bit excessive for the actual use of the post cap, unless you put up fences that are subject to vandals with hammers, and in that case, they'll break off any caps that are welded (or brazed, epoxied, pinned, whatever) well enough to pass your hammer test. If you can pull on the cap and it doesn't pull out, it's in there good enough, IMHO - in use, it's going to have gravity helping it to stay put.

I have no problem welding them on, and did it to several today.

When I had a welding repair business, I was repairing wrought iron picket spear ends all the time. Kids would walk by with a stick and hit them, and one good pop with the stick would break them off. About half revealed a cold lapped weld, usually insufficient in length, breaking off on a plane with the surface indicating no fusion. Others would break in the cast iron indicating a good weld, but a brittle cast iron spear, which is totally normal.

Testing with a hammer reveals ........... ?????????

As Lawrence wrote, most are decorative and are held on by gravity and a prayer anyway. Especially those that have the four point steel nut that is cast into the aluminum piece. I dropped a 27" fancy aluminum decoration the other day, and it broke into three pieces. Cast iron and aluminum pieces go on last, and DO NOT do well with handling.

Steve

Most of my fence jobs have been at school playgrounds. The fence encloses playing fields and regularly gets 'handled' roughly by the kids. I have a fairly high 'failure' rate (5%) of the weld and have to go back and re-weld the cap to the post. I was thinking of using an adhesive like JB Weld as an alternative. rick

School yard ?

Seems to me, the caps were targets in years past. An item of trophy class. Might be that heavy blows hit the post tops :-)

Martin

In message , Roy writes

We have sold Silicon bronze andAluminium bronze for MIG Brazing cast iron.Seems to work well.