tapered drill bits with non-tapered screws?

[Chris Friesen]

Hi all...looking for some opinions here.

I've been thinking about purchasing this set of drill/countersink bits, which are tapered to match old-style wood screws:
http://www.leevalley.com/wood/page.aspx?c=1&p=32309&cat=1,180,42240

However, most of the screws I use now aren't tapered--they're of various brands but all tend to look like this:
http://www.leevalley.com/hardware/page.aspx?c=1&p=58001&cat=3,41306

Does it make sense to have tapered holes when the screws aren't tapered? Also, when using the all-in-one bits, do people still enlarge the clearance hole?


Edit: I just found some information at McFeely's. Basically they suggest that tapered bits are not necessary/desired for the new screw style: http://www.mcfeelys.com/tech/wadb.htm

[mike holden]

Chris,
The tapered hole will mean that the straight screws will become more difficult to drive as they go in. If you are driving brass screws I would worry. For steel screws, well, it will be more work to drive them home. But steel screws break too.
It's the wrong tool for the job.
You can make it work, but, you can drill with regular drill bits, and get a countersink to match the angle of the head, either 60 degree or 82 degree and have the proper hole and countersink.
What is the fascination with the tapered drills if you are not using tapered screws?
Mike

[glenn bradley]

I've just never bought off on the whole tapered bit idea. The depth is a little too critical for my thinking; too deep and the taper is wrong, too shallow and you've got the same thing. However, I use very few screws so what do I know?

For someone who does this sort of work I imagine they are a great benefit. I would try to match your purchase to your need although I must confess there are times that I just "want" something too.

[Lee Schierer]

The clearance hole should be exactly that. The purpose of a screw is to hold one piece of wood tightly to another. A screw can't do this if the threads engage in the piece closest to the head. 9 times out of 10 you'll end up with a gap between the two pieces. With a clearance hole the threads can't get a grip in the top board and only the threads in the bottom board are working so the top board gets drawn down tight. Screws with threads the full length must have a clearance hole to do their job properly.

Tapered screws are more old school, but are still effective and plentiful. It doesn't make much sense to use a tapered drill if the screws are not tapered. Driving the straight threads deeper into the wood will create more drag, but the higher strength of the straight screws will generally overcome the drag. As a safe guard, always rub the threads of your screws across a lump of beeswax right before putting the screw in the hole. The wax will lubricate the threads and the screw will drive with a fraction of the force needed to drive a dry screw of the same size. Beeswax will melt due to the friction and wil not leave a mark on your wood that messes up the finishing except maybe with water type finishes. Parafin doesn't stick well and soap or toilet bowl rings may contain oils or draw moisture. A 1/4 pound lump of beeswax will last you for years unless you lose it.

[Chris Friesen]

What is the fascination with the tapered drills if you are not using tapered screws?

It's not so much a fascination with tapered drills, but I was hoping they might shortcut the need for three separate operations (pilot, clearance, and countersink). I suppose I could get some separate countersinks to mount on my pilot bit, which would reduce it to two operations.