yeah I get you can't drill a hex-shaped hole, but normally a bolt is cast fully formed, or and then threadded separately.

"forcing the end in with great force" seems excessive

@Criggie You just need the right tool to drill a hex-shaped hole.

@alex - basically.

@alex - in this question, the 650a rim is a few mm smaller in diameter than a 650b rim. but depending on the brake and stuff, you might be able to get it to work

is that a relaux polygon? drill bit?

Nice - so it drills enough to be equal to the inside of the hex flats, and then forces a cutter in to dig the corners, and the deeper part of the hole is there to hold the spall.

The two videos are different methods

The first is rotary broaching, which has a hex piece that... sort of rotary chisels its way in. The second is, yeah, a relaux polygon drill bit. I think that maybe can't get the corners quite as sharp, but actually removes the material instead of leaving chips in the bottom.

I guess you can also do it with a single cutting edge and a relaux guide youtube.com/watch?v=W16f-qCXVkM

Why not just cast the bolt with the hex hole in place?

I get that cast threads are a bit rough

I image someone did some maths

tooling costs, time costs, finish

and decided on the best way to do it

@Criggie I think larger and higher quality bolts are machined, not cast.

Fair warning, I've been going over some of the oldest "unanswered" questions and adding answers, even if they were answered in comments, sometimes even quoting directly from the comments, just to get "some answer" on the open questions. So there will probably be some old questions recycling.

(collecting necromancer badges lol)

@CardMechanic fair enough

@CardMechanic - its useful, since some people (myself, DRH, etc.) sometimes have a tendency to answe ra question in the comments and leave it

Does anyone here have machining experience?