Some drills have a spirit level built in that help keep things reasonably square and level. I don't particularly trust them, but if you try using it while drilling on a piece of scrap and are happy with the results, it's no extra cost.
If you don't trust yourself to "eyeball it", you can buy a drill guide (see link). If you look at the link, you'll see that it has a flat reference surface you can put up against your door. The chuck on the guide slides up and down the guide posts, so if you set the angle on the posts to 90 degrees you can drill a nice perpendicular hole. I linked to Amazon, but I've seen them in local hardware stores.
Make sure you mark your center point so you can center the bit up properly.
A forstner style bit will cut nice smooth edges. It's pretty easy to stay square using one of them too, because the walls are square to the cutting face.
Whatever you decide, it's probably worth drilling a practice hole on some scrap. It's painful to goof up a door.
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Answers & Comments
Some drills have a spirit level built in that help keep things reasonably square and level. I don't particularly trust them, but if you try using it while drilling on a piece of scrap and are happy with the results, it's no extra cost.
If you don't trust yourself to "eyeball it", you can buy a drill guide (see link). If you look at the link, you'll see that it has a flat reference surface you can put up against your door. The chuck on the guide slides up and down the guide posts, so if you set the angle on the posts to 90 degrees you can drill a nice perpendicular hole. I linked to Amazon, but I've seen them in local hardware stores.
Make sure you mark your center point so you can center the bit up properly.
A forstner style bit will cut nice smooth edges. It's pretty easy to stay square using one of them too, because the walls are square to the cutting face.
Whatever you decide, it's probably worth drilling a practice hole on some scrap. It's painful to goof up a door.
If this answer was helpful, please give it a vote. Thanks!