Difficult to weld materials technique

[nova_robotics]

They're brazing in this video, but I think the methodology might also be sound for some select welding repairs as well. They drill, tap then install screws in the area to be repaired. The screw material is weldable while the base material is not. If you did this to cast iron parts, you may be able to perform a weld repair in certain circumstances.

[WmRMeyers]

Hand shaping it on a lathe! Talk about old-school! A similar cutter could be used in milling machine, driving by a fly-cutter sort of tool holder, if you happen to have such a machine. Or just filed.

[Elizabeth Greene]

I'm impressed;That's beautiful. 10/10 for hand indexing a gear while cutting the teeth by broaching using a ground form tool on the lathe. That's awesome!

[mansworld]

Too many close spaced holes will weaken the structure. A better approach is to drill less holes, say 3 or 4 screws spaced apart, and stay away from the edge/face of the gear.

[NortonDommi]

Cast Iron is usually easy to gas weld with a good rod. Bronze welding also works well and is ideal for many gears, amazingly strong and tough stuff. The guy did a nice job but the screws probably aren't needed for anything more than a framework.
Bronze could be Tobin for small gears but for large ones under stress Manganese Bronze or Nickle Bronze would be better.
Just thought I'd throw in stitching for crack repair. it is common, can often be done in situ and once peened indistinguishable from the surrounding area.
https://www.metalockengineering.com/...tal-stitching/

[Isambard]

Reminds of a job my father did back in the Depression. He was working in a quarry up a river where there was a only steam power.
Several teeth stripped on the rock crusher. My father hand drilled holes on a 8" face for 1 inch bolts! He then filed the profiles...
A replacement gear was months away, apparently.

[desbromilow]

a bit cringey at 7:46 when you observe the electrical "box" on the work bench in the background - single cores jammed into the GPO
noticed a lot of slop in the machine - tool post appeared to tilt/ lift a few times, and the spindle lock wasn't - just goes to show how a craftsman can compensate for the limitations of their machine.

[Skun Knuckles]

I was told many years ago “Do what you have to do to get the job done!”

[clydeman]

I did this to my large lathe about40 years or more ago. I didn't remove the gear as it was on a large group. I just drilled the holes, taped them, put the studs in, welded them and then free hand ground the teeth to shape. It was a 16X48 inch and has worked fine
every since