Richard this is the hole saw drill I used to make the holes.
You remove all the saw blades apart from the one you want by unscrewing the flat head screw, but you can also reduce how far the drill sits above the sawblade by undoing the cross head screw and moving the drill bit..
So in theory you could set it so that the drill is short enough to pass through the ali but not so long as to hit the gearbox.
Let me know if you want to borrow it.
![[Linked Image]](https://www.tm-img.com/images/2022/10/18/20221018_101541.jpg)
![[Linked Image]](https://www.tm-img.com/images/2022/10/18/20221018_101548.jpg)