Bought to remove steel rivets for a job installing/repairing parcel boxes. They dull very quickly, even with frequent application of oil to the ends of the bits. I bought a second set to make sure the batch isn't defective. This time I tried drilling the pilot holes with a smaller bit (the bits broke), was careful about the amount of pressure I was applying, and the main problem is still that after a few uses, the drill bits become dull, even when oil is applied. Find a different/better set ofβ¦