I use J B Weld epoxy glue for repair of metal but the best filled epoxy for metal repair is the more putty like old timer, Marine Tex. Marine Tex epoxy is filled with non metal fumed silica or something similar.
Marine Tex has been used to repair aluminum boats for years and I repaired a 12 inch long by 1/2 inch under water gash in a boat in the early 1960s that lasted 20 years until I sold it.
Marine Tex has been used to repair cracks and holes in engine blocks, transmission and differential housings with success for years. Lots of smart boat owners never leave shore with out a pint or so.
Marine Tex is more putty like and will stick to a vertical surface better and fill gaps better than J B. It also is much harder and will mold parts and hold a cut thread better than J B. I can easily cut and carve J B with a knife and Marine Tex must be filed.
I recently repaired a die cast bearing seal cap or 60 year old 24 inch Delta jigsaw. The cap had disintegrated and had missing pieces and I had to fill in the voids.
Marine Tex can now be purchased at good boat dealers, and now even Walmart, Amazon, Ebay etc. but costs about twice as much as J B Weld. Both epoxies and most glues will last longer after opened if one stores them in a refrigerator.
Another Epoxy Putty to consider is Devcon Plastic Steel 5 Minute Epoxy Putty. I have used it and it is very similar to Marine Tex. It is steel filled and good to 350 F. The box gives instructions for machining with a lathe. ITW Devcon makes epoxy putties filled with several other metals and ceramics.
Charlie