First, drills seem to take longer to gain energy than they lose it. This causes the drill to keep shutting off, as it has no energy in it, and it is really annoying to have to constantly turn on the drill.
Second, It appears that under the right circumstances, the drill can move forward even when there is still blocks to mine. I have a cobble generator, and it uses a drill. I turned on the drill, it was working fine, when randomly, it moved forwards, even when it never even dug out the bottom 2 blocks.
There are 2 issues.
First, drills seem to take longer to gain energy than they lose it. This causes the drill to keep shutting off, as it has no energy in it, and it is really annoying to have to constantly turn on the drill.
Second, It appears that under the right circumstances, the drill can move forward even when there is still blocks to mine. I have a cobble generator, and it uses a drill. I turned on the drill, it was working fine, when randomly, it moved forwards, even when it never even dug out the bottom 2 blocks.
here's a pic: http://i.imgur.com/NIrYoqG.jpg