I was going to drill through into the down tube first with a very fine bit to prevent having the tap bottoming and breaking.
Originally Posted by
WizardOfBoz
If you are planning on drilling into a modern, high strength frame and then tapping the frame, it won't work. Not anything I'd try, anyway. The alloy or steel is very strong and so is used in very thin wall sections so its too thin to hold threads.
I suspect [MENTION=466491]WGB[/MENTION] meant to drill into the tube through the boss, so he could use a standard plug tap to re-thread the boss rather than searching for a bottoming tap. But your point about drilling modern, heat-treated alloys is valid. Depending on the specific frame material, it might be a bit of a chore.