Columbia Travel Arm Repair

[edisonclassm]

I guess I am going to have to explain the minutiae involved here.
Cast aluminum is somewhat porous. When glue is applied it absorbs into those pores. It is nearly impossible to remove every trace of glue if you choose to weld it. When the heat of a weld is applied the glue creates gasses which repel the weld. Also the residue from the glue repels the weld. You end up with a real mess! Uncontaminated surfaces accept the weld beautifully if done properly. If you want a short term unstable fix use glue. Especially if you don't care about the next collector who may own this machine in the future.

[Django]

I guess I am going to have to explain the minutiae involved here.
Cast aluminum is somewhat porous. When glue is applied it absorbs into those pores. It is nearly impossible to remove every trace of glue if you choose to weld it. When the heat of a weld is applied the glue creates gasses which repel the weld. Also the residue from the glue repels the weld. You end up with a real mess! Uncontaminated surfaces accept the weld beautifully if done properly. If you want a short term unstable fix use glue. Especially if you don't care about the next collector who may own this machine in the future.

For a proper TIG weld repair you have to bevel the edges, so a welded repair should only involve freshly exposed metal. A friend TIG welded a Columbia traveling arm for me many years ago, (I can weld, but TIG welding an Aluminum casting is an art). In that case I machined a new section to be welded on, and finish machined and blended the surface after welding. The repair was strong and invisible. Basically, the break area can be ground back and the gap filled, or a piece of aluminum plate can be welded on and machined in place, insuring an accurate hole. Good luck

[Curt A]

Django's quote: TIG welding an Aluminum casting is an art

He is exactly right... welding a small aluminum piece like that arm takes an experienced welder who is used to welding small aluminum parts... I took an iron part to a welder for repair and even though he was experienced, he blew a hole through it... That being said, I believe a welder who is capable of repairing that arm would be hard to find and I wouldn't trust it to just anyone, since it could be damaged beyond reasonable repair. So, if the glue works without a problem, why not use that method? As far as collectors in the future, they will probably be able to print a duplicate piece...