Seatposts of that type (forged clamp section into pipe) are usually cryofitted together just like fork crowns/steerers etc, which you will really struggle to do at home (or even in a decent engineering workshop!).
So you want a seatpost to fit a 24mm frame?
Buy a cheap/used 1"/25.4mm seatpost and get it machined down, someone might charge you £10 for the pleasure. Much safer and more logical I'd have thought?
Seatposts of that type (forged clamp section into pipe) are usually cryofitted together just like fork crowns/steerers etc, which you will really struggle to do at home (or even in a decent engineering workshop!).
So you want a seatpost to fit a 24mm frame?
Buy a cheap/used 1"/25.4mm seatpost and get it machined down, someone might charge you £10 for the pleasure. Much safer and more logical I'd have thought?