I had to drill some 1/2 inch diameter, 4 inch deep, holes in concrete, I used my Ryobi 1/2 inch hammer drill. The chuck is a keyed Jacobs chuck. The bit had a step milled into the shaft. The drill runs like a champ, but the chuck kept comming loose, which required me to stop every few minutes and re-tighten it. That got old real quick. I thought it was the step in the bit so I ground it back so it wouldn't interfere with the chuck jaws when it bottomed. Still lossened. Is this just the nature of hammer drills? Or is there some other trick or tip I can use to keep it tight? I usually don't drill 1/2 in dia holes, so I never had this problem before. Thanks.
