I agree with Damon, that has to do with chatter, the drill is actually moving up and down to allow such a thing to happen. Now why? Two things come to mind. The first is much less likely but I thought I'd point it out, I've seen a least one bit that you ran the drill 'backwards' for the countersink to cut correctly.

This will cause the same issue as the other one. If it is really dull countersink it will chatter no matter how strong you are. (a backwards one is using the dull side so works the same). So I would recommend either sharpening it or getting a new one.

I just did a little search and counter sinks, and I think I need to invest a little on some of the nice one that will drill my hole and counter sink in one go! Anyway you can get them really cheap or pay some decent money for them.

Edt: after seeing you have an electric 'screwdriver' not a drill, I would say this is allowing the chatter. Those really are not designed well for this type of application. You don't need a cordless drill to do this, allowing for a much cheaper corded drill to be added to your tool set.

As another note, a hand drill with a large sharp bit could be used to round them out after you have them close, which might be cheaper yet.

I agree with Damon, that has to do with chatter, the drill is actually moving up and down to allow such a thing to happen. Now why? Two things come to mind. The first is much less likely but I thought I'd point it out, I've seen a least one bit that you ran the drill 'backwards' for the countersink to cut correctly.

This will cause the same issue as the other one. If it is really dull countersink it will chatter no matter how strong you are. (a backwards one is using the dull side so works the same). So I would recommend either sharpening it or getting a new one.

I just did a little search and counter sinks, and I think I need to invest a little on some of the nice one that will drill my hole and counter sink in one go! Anyway you can get them really cheap or pay some decent money for them.

Edt: after seeing you have an electric 'screwdriver' not a drill, I would say this is allowing the chatter. Those really are not designed well for this type of application. You don't need a cordless drill to do this, allowing for a much cheaper corded drill to be added to your tool set.

As another note, a hand drill with a large sharp bit could be used to round them out after you have them close, which might be cheaper yet.

I agree with Damon, that has to do with chatter, the drill is actually moving up and down to allow such a thing to happen. Now why? Two things come to mind. The first is much less likely but I thought I'd point it out, I've seen a least one bit that you ran the drill 'backwards' for the countersink to cut correctly.

This will cause the same issue as the other one. If it is really dull countersink it will chatter no matter how strong you are. (a backwards one is using the dull side so works the same). So I would recommend either sharpening it or getting a new one.

I just did a little search and counter sinks, and I think I need to invest a little on some of the nice one that will drill my hole and counter sink in one go! Anyway you can get them really cheap or pay some decent money for them.

I agree with Damon, that has to do with chatter, the drill is actually moving up and down to allow such a thing to happen. Now why? Two things come to mind. The first is much less likely but I thought I'd point it out, I've seen a least one bit that you ran the drill 'backwards' for the countersink to cut correctly.

This will cause the same issue as the other one. If it is really dull countersink it will chatter no matter how strong you are. (a backwards one is using the dull side so works the same). So I would recommend either sharpening it or getting a new one.

I just did a little search and counter sinks, and I think I need to invest a little on some of the nice one that will drill my hole and counter sink in one go! Anyway you can get them really cheap or pay some decent money for them.

Edt: after seeing you have an electric 'screwdriver' not a drill, I would say this is allowing the chatter. Those really are not designed well for this type of application. You don't need a cordless drill to do this, allowing for a much cheaper corded drill to be added to your tool set.

As another note, a hand drill with a large sharp bit could be used to round them out after you have them close, which might be cheaper yet.