That sounds like quite a flowerbox. Goodness. I'm not incredibly familiar with masonry drill bits, but my understanding is that they aren't as sharp as bits meant for drilling in wood (the general purpose kind that probably came with the drill). Switching to a masonry bit may actually have caused the drilling to fail for an entirely new reason. I think how a masonry bit works is that you're meant to use it with a "hammer drill", which both rotates the bit and hammers it into the wall -- the hammering action causes chunks of masonry to break up, and the rotation of the bit (which is hardened to survive the hammering) scrapes the chunks out of the hole. With a wood bit, the sharp edge of the bit actually cuts into the wood (assuming you're putting some pressure on it, but you shouldn't need to put your whole body weight into it, generally), so the rotation both cuts the wood fibers into sawdust and channels sawdust out of the hole. Using a masonry bit on wood might not be accomplishing the "cuts the wood fibers into sawdust" part, so you might just be compressing the wood fibers into the bottom of the hole until they won't compress any more.
I think there's still some confusion about speed and torque which might be getting in your way, too. The numbered ring on the drill controls torque, not speed. Torque is the amount of power that is transferred from the motor of the drill out to the bit, whether it's a screw driving bit or a hole drilling bit. Some cordless drills have a setting just past the highest number on their torque that's a little icon of a drill bit -- when you set the torque to that setting, it locks the clutch and essentially gives the drill infinite torque, which is generally what you want when drilling holes unless you're using a very small bit (1/8 inch or less, probably) and are worried about breaking it. One way to think about torque is to think of how your hand works with a doorknob (the round kind, not the lever kind). If you grasp the knob gently, you can turn it until it won't turn any more -- your hand will slip around the knob. That's low torque. If you grasp the knob very firmly, you could really wrench on the knob and possibly break it off if you kept twisting after it wanted to stop. That's high torque.
Your drill has a clutch that works like your hand on the doorknob. The motor is your arm, and the chuck (the part the bits go into) is attached to the shaft of the doorknob. Power is transferred from the motor (your arm) to the chuck (the doorknob) via the clutch, which is your hand. The higher you set the torque to, the more firmly the clutch grasps the knob, and the more power gets transferred from the motor to the bit. How this works in application is that if the torque is set too low, you won't be able to drive the screw in all the way, and if the torque is set too high, you could drive the screw all the way through the wall and out the other side. It takes some experimenting to find the right torque setting for any particular job.
With the torque set too low, it can feel like the bit is spinning and stripping the head of the screw, even if that's not what's happening. As long as the driver bit is being pressed firmly into the head of the screw, the slipping should all be happening inside the clutch.
With the torque set high enough, it can be difficult to keep the driver bit pressed firmly into the screw head. If you're leaning in and putting your weight through the drill, but it's still kicking the bit out of the screw head and stripping it when you squeeze the trigger, the problem is either that you have the wrong size driver bit for the screw, or that you're squeezing the trigger too hard.
How hard you squeeze the trigger is what controls how fast the motor turns. If you hold the drill so that you can see the bit -- away from any screws, just in the air looking at the bit -- and squeeze the trigger lightly, you should be able to see the bit turn slowly. And I do mean lightly -- the trigger should only move in towards your palm a little way. If you squeeze the trigger more firmly, so that it goes all the way back as far as it can go, the bit will probably turn so quickly it's a blur. And there's a range of speeds in between. In my experience, slower works better when driving screws. Well, not _too_ slow, obviously, but slow enough that you maintain control. At high speed, regardless of torque, it's just difficult to keep a bit in a screw.
The third thing, which is only really a factor when drilling holes, is how tightly the chuck jaws are grasping the drill bit. Drill bits tend to have round shanks (the shank being the part of the bit that isn't fluted), while driver bits tend to have hexagonal shanks. A hexagonal shank can't really slip in the chuck once it's tightened past a minimum point. A round shank can, and if that's happening then the motor will be turning the chuck just fine, but the drill bit won't be rotating at all. This is hard to see at high speed, so if you suspect it's happening, try squeezing the trigger really gently and watching the bit closely to see if it's turning or not. If it isn't, it's stuck in the wood more tightly than it's stuck in the jaws of the chuck, and pulling straight back on the drill will probably leave the bit stuck in the wood while the drill comes away. And then you need the pliers to get the bit back.
Probably the easiest way to get the bit stuck in the wood is to try to drill all the way through something thick in one go. Normally, sawdust created by the cutting edge of the bit gets routed out the back of the hole through the flutes in the bit, but if the sawdust gets compressed and jams, then you end up wedging more and more into the flutes until the sawdust won't compress any more, and binds everything together. The way to avoid this is to, a couple times for each hole you drill, keep the drill running and pull it back out of the hole. Check the flutes to see if there's compressed wood stuck in them, and tap it out or scrape it out with the point of a screw if there is. Then put the bit back in the hole, squeeze the trigger and drill some more.
It might be useful to get a piece of 2x4 a couple feet long, clamp it (or have a friend sit on it) hanging over the edge of a table or something (so you don't drill into the table) and then practice on that, both drilling holes and driving screws, to get a feel for how the drill works at different settings. At least with that, you'd know that there was no chance you were hitting a hidden metal plate or fossilized mud or something.
Oh! And one last thought, just to confuse things even more. For drilling a (drainage?) hole in a flowerbox, or other times when you need a larger hole and don't care too much about it being super precise or clean, you might want to get some spade bits, like these:http://www.amazon.com/Irwin-Industrial-341008-Speebor-8-Piece/dp/B0000EI9B0/These wouldn't be something you'd use to drill a pilot hole for a screw, or make a hole in drywall or metal -- they're for removing a lot of wood quickly, and leave a rougher exit hole than a twist bit (the kind that came with the drill). But they have a hexagonal shank, which eliminates the possibility of slipping in the chuck, and they drill right through most woods like butter. If your flowerbox is made of teak or ironwood or something like that, you're probably better off just building a new flowerbox.
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I drill in slowly, then in and out. It helps release the detritus formed by the drilling.
posted by taff at 4:41 PM on September 22, 2012