Drill wont tighten to drill holes - what am i doing incorrectly

Katie,
Refer to the picture below. Loosen the locknuts (the one on the right side of the drill is shown, there is another on the left side). Use the lever to move the motor toward you, thereby loosening the drive belt(s). Open the top cover to expose the belt(s) and sheaves (most people incorrectly call them pulleys). You might have one belt and two sheaves, or you have two belts and three sheaves. The drill will go fastest when the belt is on the biggest motor sheave and the smallest sheave on the drill spindle. Of course the opposite sizes apply for the slowest speeds. Make sure the belt uses a pair of sheaves that are at the same height as each other (the belt has to stay in one plane). Now tighten the belt(s) by pushing the lever pretty hard away from you, and while holding it with your right hand tighten the left side locknut with your left hand. Now tighten the right locknut. Close the cover. ----- OK, so now you know how to CHANGE speeds, what about drilling glass? This can be tricky. You must use a pretty slow speed (maybe the slowest, depending on the size of hole you are drilling. And you must keep the spot you are drilling flooded with water to keep the glass cool. And you must apply pretty gentle pressure. And the use of a drill bit intended for drilling glass helps a lot. And don't try the first hole in something expensive! Practice on something disposable first. Take your time. AND WEAR SAFETY GLASSES!
Good luck!

Hi. I'm guessing it is a keyless chuck. I always have to use two hands to tighten mine. Is drill running forward and not in reverse?

Although you posted your question under Chainsaws instead of another tool forum, look at the end of the drill. Is there a hole surrounded by a cone shaped metal end? This is the chock, if you spin/turn it counterclockwise, the opening should widen to accommodate the drill bits, then spin/turn it clockwise to tighten/clamp down on the drill bit. Some drills accomplish this with an l-shaped key that has a small cone-shaped gear on the end that fits into holes on the chock. Some drills have a chockless drill, and you simply hold the end of the drill and squeeze the trigger to use power to tighten/loosen the bit.

You have to tighten the chuck more. Tighten in all three holes to get even pressure on the bit.

I have one of these.
Here you will see how the drill is mounted in the device. Position (b) around the handle and tighten it up untill drill seats firmly in place. Take a speed square, or normal square and eyeball or measure the drill to see if its straight. Use the alignment adjustment (A) to fine tune the drill to get the drill bit straight and square. Tighten up all the nuts holding drill in device and recheck the drill bit for straightness.. Put your work under the drill, press the trigger and lock into place to get the drill to constantly run without finger on trigger, pull down the press lever to drill your hole... Hope this helps!

When the drill bit on a hammer drill keeps loosening up one of two things is happening. 1. The chuck is worn out and needs to be replaced. 2. The chuck is not tight enough before you start drilling. If you have the style of chuck that requires a key do not be bashful about using maximum force to tighten the chuck and move the chuck key from hole to hole and tighten it in each position. Joe

your must have a keyless chuck. hold the black center part of the chuck and run the drill forward or backward to open or close the chuck.

there is a rippled edge close to the very tip of the drill and there is a key supplied with the drill with the corresponding ripples place key into the hole near tip of drill so ripples meet each other and turn key in an anticlockwise direction to loosen put in new drill bit re tighten in clockwise direction hope this helps if not please ask for more info glenn

adjust tension on pully or the belt may be worn or streched replace belt.

Assuming that it is this drill:

http://www.toolpartsdirect.com/cgi-bin/schematic.cgi/blackdecker/7144-04_TYPE_4

You will need a chuck key - hopefully you have that with the drill. It's a little t-shaped bar with a cog on one end. You put it into the holes in the chuck (the part at the end which grps the bit) and turn anti-clockwise to open the jaws. Place a bit in the centre and then turn it clockwise to tighten. Tighten the bit using each of the three holes in the chuck and make sure you remove the chuck key before you use the drill - keep it safe!