Gripper Cam Mystery

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The piece is cast iron. Welding sets up internal strains in any metal and cast iron is brittle. A good way to weld cast iron is forge welding, where the part is heated slowly and completely in a forge until it is all approaching dull red heat, and then the welding or brazing is done while it is hot. The piece is then allowed to cool slowly. This process reduces the chances of internal strain. Also, the cross section at the weld should be greater than the original part if there is room for it, since the extra metal also adds strength. Brazing seems to be better since the metal is at least as strong as the cast iron.


Thanks for your feedback Bob.

As far as I know the piece was forge welded and brazed. The person who did it knows about these machines and what they’re made out of, and reported that the piece took about five hours to fix.

Would you recommend getting it welded again? Do you think it’s possible that the problem could be my machine and not the gripper cam, as my welder reports?

“…the part is heated slowly and completely in a forge until it is all approaching dull red heat, and then the welding or brazing is done while it is hot..”

Sorry, not to be pedantic, but that isn’t forge welding.

What you described is a simple (and common) welding technique merely called “pre-heating”. Pre-heating cast iron to between 600 and 1200°F is the norm.

Last, and just looking at that part in the photo, are you sure it is cast iron?


Hi Tom,

Pedantic is welcome. Helps me to be more specific in the future.

The piece came with the press, which was rescued from a basement after languishing there for about fifty years. The person who welded it told me it was cast iron, and is very reputable. I trust that he identified it correctly, particularly because it came to him broken cleanly in half (allowing him to see it inside and out). It certainly looks and feels like the rest of the cast iron parts on my machine. But can I say with 100% that it’s cast iron? No.

If it’s not cast iron any suggestions on how to proceed? More photos are attached.

image: 2010-07-01 18.02.24.jpg

2010-07-01 18.02.24.jpg

image: 2010-07-01 17.59.41.jpg

2010-07-01 17.59.41.jpg

Although it is not my trade, I did become an actual certified welder at one point in my life.

I could not tell from the photo (and still can’t) what the material is, and would happily accept what your welder said given that you said he is knowledgeable in his work.

I would use a slow pre-heat and weld with a nickle rod, as machining is apparently required here after welding. I would v-grove grind the part then fill with weld, short beads perhaps peening as it is laid to combat shrinkage.

Again, any knowledgeable welder would do exactly that anyway, so I am not revealing any deep dark tricks of the trade here.

Then I would do a LONG cool-down, with the part wrapped in insulating material or buried in dry founders sand or equivalent.