Anyone using center drills?

Good day.
I am looking to mark the center/starter holes in Alum and steel.
Anyone else doing this? which center drill or other methods are you guys using?

Thank you!

It wasn’t clear from the terminology used to ask the question exactly what you are looking for? The wording ‘mark’ threw me a bit there. Assuming here you are asking about how to start a hole without plunging?

Quite a few of us here use helical entry to clear chips while starting a hole. Most modern CAD systems support helical entry which can be quite helpful, but possibly there is a missinterpretation of the question here?

Maybe I should have said a small pilot hole. for instance in alum for the machine to drill a small 2.5 mm hole at 2 or 3mm depth. Tnx.

Would a 120or 135deg carbide NC-Spotting drill suffice to create the initial divot and ensure that the follow on twist drill does not wander?

I use 1/2 size of the final hole end mill. I use flat or square noses end mills so I don’t ruin my flow through table top.

The main thing I cut are holes for rivets in aluminum sheet for aircraft. Usually custom ribs and skins as a builder assistance type service.

I never use drills because they have a point and they tear up the flow through table top and then nothing will stick to it.

Which is why I rant and rave about people cutting gashes in their spoilboards. Drives me nuts. My spoilboards go bad because of expansion from moisture, almost never because of end mill gashing.

PS. I do take the holes larger with a second tool but the starter hole is most what folks want because of cost.