Re:
Centre punch first to stop the drill bit wandering.
If you want to design a layout for holes then you can use and drawing / CAD software, if using drawing then use if a grid can help. Search google images for an image of a grid if your software doesn't have one and draw over it.
Then draw the holes accurately where you want them and mark the centres. Then you can print it out and centre punch all the centre marks on the part in the correct locations.
Pilot drill then drill under size and use a new drill bit for the correct size so it cuts metal rather than pushes it and causes a burr on the inside of the seatpost.
Use oil on aluminium to prevent it sticking to the drill bit, anything, WD40 is good.
Centre punch first to stop the drill bit wandering.
If you want to design a layout for holes then you can use and drawing / CAD software, if using drawing then use if a grid can help. Search google images for an image of a grid if your software doesn't have one and draw over it.
Then draw the holes accurately where you want them and mark the centres. Then you can print it out and centre punch all the centre marks on the part in the correct locations.
Pilot drill then drill under size and use a new drill bit for the correct size so it cuts metal rather than pushes it and causes a burr on the inside of the seatpost.
Use oil on aluminium to prevent it sticking to the drill bit, anything, WD40 is good.
