Homemade diff pin?

[redshift]

Yes, but I should have mentioned that if the drill bits were made of true HSS they'd be unusable. There is a tradeoff made, lower hardness= increased ductility. If you've used a solid carbide drillbit you know how fragile they are. By compromising, you also lose some long wear characteristics. But think how annoying it would be to replace a shattered drill bit every time you had a snag. That's why the TiN coating caught on so rapidly, because the bits can have the flexibility of standard HSS combined with greater wear resistance.