On Tue, 8 Jul 2014 20:10:42 -0400, "Ralph Mowery"
wrote:


"Anthony" wrote in message
...
On Tuesday, July 8, 2014 10:52:14 AM UTC-4, Ralph Mowery wrote:
If you do not drill the first board it will be difficult for the boards
to

pull up tight. You have to drill the first board with a large enough
hole

the screw threads do not cut into the wood and you let the head of the
screw

keep the wood from pulling back.

I did pre drill the main hole, but of course it was smaller than the
screw. are you saying I should have made a larger pre drill hole? I would
have no problem in unscrewing it and make a larger drill hole?

You need to drill the hole on the top board large enough that the screw
threads do not touch it. If you do not do it this way, whatever gap you
have in the boards when the screw goes into the lower board will tend to
stay there

I get your point, but in case the OP hasn't, Imagine a long machine
screw and you screw a nut on half an inch down the screw. Call this
the first nut. Then you screw a second nut on, so the two nuts are a
half inch apart. Then you hold both nuts between your thumb and your
forefinger and turn the screw clockwise. Both nuts will get closer to
the head but they will stay 1/2" from each other. When the first nut
reaches the head of the screw or the end of the threads, the screw won't
turn anymore and the second nut will still be a 1/2 inch from being
tight, and were there anything between the two nuts, it would not be
tightly gripped.

The first nut (that is, the hole in the first piece of wood) needs to be
big enough that it can move up and down the screw without needing to
turn the screw. The hole in the first piece, the top piece, of wood
needs to be bigger than the threads in the screw.


unless by chance you strip out the threads in the upper board.
The screw should hold by the head and not depend on the threads in the board
where the head of the screw is.

In effect you are only screwing into one of the boards.