View Full Version : Drilling Bascis

09-28-2006, 05:32 PM
How do I find out what drill speed & torque I use for drilling & screwing? My drill has dual speeds (0-350/0-1100) and 21 torque settings.

Screwing into wood: TORQUE - Is it true that the larger the screw size / desired depth, the greater the torque needed? If so, what torque is used for what size screw / depth? Or is the highest torque setting marked with a screw symbol because you always use it? SPEED: Should I use the lower speed setting in bursts for screwing onto wood?

Drilling into wood: How do I find out what torque to use for various bits sizes? Do I always use the high speed for drilling?

09-28-2006, 06:04 PM

What are you attemping to accomplish? What material are you drilling into, and for what purpose? Most homeowner do-it-yourself projects are not critical as far as speed or torque for drilling holes. I have a Dewalt cordless drill, 14V, that I used on "high" speed for wood and metal drilling.

For screwing, same thing applies. I lock the slip clutch on my Dewalt in the "locked" position. The key to not overtightening is experience and being careful. A good practice is to use your power tools to get the screw close to tight, then hand tighten the last turn or so. This will prevent stripping threads in the wood.

Anyway that's a start. Need more info on what project you are working on.

If you are running a professional woodshop to make money, you need to get into the details. The comments I made are catered toward the homeowner/do-it-youselfer.

09-28-2006, 06:52 PM
For now I am building a fence and a gate with treated softwood. The 1x6 (3/4" x 5.5") fence boards will be screwed onto 2x4 rails using two diagonal 2" deck screws per rail. Without pre-drilling, they would not go all the way in, so I am planning on pre-drilling. I would like to sink them flush with the surface but not strip them so as to lose their grip. Thanks for suggesting I hand tighten the last turn or so.

09-28-2006, 07:22 PM

You will be fine with using wood screws sold for building exterior decks. You won't need to pre-drill holes with the lumber you are using. You'll get the hang of how far to install the screws after a few tries. It's not hard and you'll do fine.

09-28-2006, 08:00 PM
Generally speaking, you use maximum speed and maximum torque for drilling holes (in wood). You use lower speed for screws. As for the torque you need for screws, it's best to start low and work your way up. You can always dial up the torque if you have to, but if you use too much torque, for drywall, or door hinge screws, etc., you will have problems. Once you get the hang of adjusting the "clutch" you won't need to do any hand tightening. Get yourself a nice screw guide. It's absolutely essential.

09-29-2006, 06:31 AM
Sears, and other companies, used to make a bit that predrilled for the thread, shank and countersink all in one. I still have my original set so I haven't had to look to see if they still make them.

09-29-2006, 06:43 AM
The torque setting on the drill is actually the level at which the chuck slips. The lower the setting, the quicker the chuck 'backs off' any turning resistance it gets.

If you have the patience, the best way to screw is to:

1) predrill your holes (at high speed and the highest torque) a size smaller than the screw - so that there's not much wood to displace.

2) Countersink your hole. Get a countersink bit that's long enough to screw the pilot AND cs the head.

3) Drill at middle torque. If you need more you didn't predrill enough. The screw should only have to dig it's threads. It doesn't have to displace any wood or pull its head flush.

This'll max yr battery usage and minimize splitting.

I highly recommend some kind of quickchange chuck/bits like Dewalt or Jackrabbit. They'll make switching btn drill/driving easy.

Alternatively, you can rent an impact driver which is to drill/drivers as a hammer drill is to reg drills: it has a piston that hammers the screw as it twists. It has double the torque of the reg drivers. Saves time and yr wrist.

Gary Swart
09-29-2006, 01:31 PM
I use a 3/8 DeWalt VSR for all my screwdriving. You don't want to try to go too fast because the bit will cam out the slots. For decks, framing, and etc., I use square drive screws exclusively. On a deck or other surface where appearance matters, I predrill and countersink. I don't have bits like HJ suggested, I use drills for this. One is a second 3/8 VSR and the third is a Makita 9 volt. (Both DeWalts are corded.) The DeWalts will punch the square drive screws clear to China, but the entry hole is crappy looking without predrilling and countersinking.