Lack of oxygen?

I use a bucket as opposed to a carboy for fermentation and in the past had pitched the yeast and then shake the hell out of it to oxygenate. However, out of concern that that menthod really didn't generate enough oxygen, I purchased a tool that attaches to a drill and essentially stirs the beer very hard. Theoretically, this was a better method to oxygenate. However, the last batch after 5 weeks in the fermenter had not fully fermented and ended up overcarbonated in the bottles. I should have taken a final gravity reading before bottling but didn't because I was confident that after 5 weeks it had to be finished. So now I'm onto a new batch and it has been three days and I am not yet getting any airlock activity. I'm beginning to think that this areting tool isn't doing the job. Is it to late to shake it? Do I just need to be patient? Let me know what you think?

I would take a gravity reading to see if it is actually fermenting. Regarding the oxygenation of the beer, listen to this podcast (August 7, 2008) about shaking versus pumping. In their experiment, they have shown that an aquarium pump is no different than shaking a carboy or bucket. So, I would venture to say that if you did oxygenate your wort with your attachment you probably have as much saturation as your going to get without utilizing pure O2.

Buckets are notoriously leaky - you can't use airlock activity as an indicator of fermentation with them. To do that, you need a carboy or Better Bottle with a tight-sealing bung or universal stopper.

By the way, shaking and stirring are equivalent in terms of maximum oxygen saturation, and either one works fine for all but the most extreme beers.