If it’s a cheep bike drill and tap away…But I would not touch a forged campy dropout…I would also not lay heat on the dropout, if you don’t know what you are doing you can mess up existing welds…If you do all the measuring and show me where you want it I have a mig welder and can tack it for you (if I still have gas in it).
“I would also not lay heat on the dropout, if you don’t know what you are doing you can mess up existing welds…If you do all the measuring and show me where you want it I have a mig welder and can tack it for you (if I still have gas in it). “
You are willing to mig weld on a bicycle and you think a propane torch is going to mess up some existing welds? Wow.
Yes I would use a mig welder to tack an eyelet on a bike dropout and it would look good!
You can’t braze anything with a propane torch it does not get hot enough. You need a gas mixture that creates enough heat to allow the metals to reach the eutectic point. Propane torches are made for soldering copper pipes.
The majority of mass produced steel bicycle frames are not welded with tungsten. They use cheep alloy and any post weld reheating with a torch will induce stress and cause cracks.
OMG it’s almost 10PM on a Friday… I’m going to the bar!
If a torch would cause cracks, how would mig welding it be any different, other than you would be heating it up more than a torch?
Do some searching on the interwebs, there are a lot of people who built bikes with a basic MAPP gas torch. I would not do that because I have the proper tools (TIG and oxy/acyl torch) but I find it intriguing that people do it.
My limited experience with MIG would indicate that the heat is significantly more localized…more heat, much smaller area, much less time. Using a torch would produce a significantly larger HAZ in most cases.
Personally, I wouldn’t want to MIG anything to a thinwall tube (I’d go with the TIG or oxy/acetylene, too, for preference), but welding an eye to a 3/8″ or 1/4″ solid dropout via MIG seems pretty reasonable.
Sorry, perhaps I wasn’t clear. I’d expect far less overall heat to be dumped into the metal with MIG than with a torch. The MIG will not dump anywhere near as much heat into the surrounding area, as it’ll only be applied for a second or two at a very small point.
My concern about MIG for use on tubing, rather than dropouts, is simply that I’ve found it very easy to blow holes in the tubes. Someone with mad MIG skillz could probably do it, but I wouldn’t.
So, in summary, I’d say that MIG or TIG would be the simplest way to add permanent eyelets to dropouts. Brazing or gas welding would likely introduce more heat into the joints between dropout and stays, so I’d be more cautious about those approaches.