As an alternative to making an actual axe head you could create a simple chisel, which you then hit with a piece of wood that servers as the hammers.
This can be used fairly efficiently to slowly cut through even larger trees and has the several benefits versus a proper axe:
- A chisel is far quicker to make and thus more easily replaced.
- You save yourself the headache of creating the binding between axehead and handle, which is quite tricky and will probably fail the first couple of times unless you know exactly what you're doing.
- As with any stone tool you should not be putting it through the works like you would a modern day steel axe - while using a chisel you're less likely to strike with too much force thus breaking your axehead or handle.
Example:
The channel Primitive Technology the guy shows how to use a chisel while creating a proper axe.