If I am going to use screws along with glue, should I drill pilot holes
prior to putting any glue on the board edges? Or do I glue and clamp first,
then drill pilot holes, and lastly screw in the screws?
Regarding the pilot hole, does the pilot go into the first board only or
through both boards?
Lastly, does the order change any if I'm cutting holes with a forstener bit
Depends. If you're using traditional slotted woodscrews, you'd glue,
assemble and clamp the piece, run the pilot through both components to the
full depth of the screw. You'd then run a clearance bit, just a tad smaller
than the diameter of the unthreaded shank, through the upper component only.
Then you'd countersink the upper component to take the screw head.
Note that you can buy special drills nowadays to carry out all three
operations in one pass. They come in sets for varying gauge screws and are
not too expensive if you intend to do a lot of this type of work. These can
usually counterbore as well as countersink, so you might not need a
forstener to male your plugholes. I say might, because they don't generally
give as clean a hole as the latter.
If you intend to counterbore with a forstener bit, these bits really need a
solid surface for the centrepoint of the bit to grip to start them. If you
try to locate it in the clearance hole, then you may not get it accurately
centred and, worse, it may wander as you try to start it, scarring your
work. In this case, I'd run the counterbore with the forstener first, then
use the pit made by the centrepoint to locate the pilot, then use the pilot
to locate the clearance bit.
For rougher work using modern screws, I'd simply drill the clearance hole in
the upper component. These screws have a spiral fluke which effectively
cuts its own pilot, so all the clearance hole does it help it to stay
aligned as you drive it, and gives the head a start when in comes to
countersinking itself. The clearance hole also helps you avoid splitting
For simple glue-and-screw butt-joints, before you glue and assemble you can
bang in panel pins along the mating edges (ie where the glue is going to
go). Leave them standing about 1/4" proud, then snip them off with
piers/sidecutters, leaving about 1/8" proud. These small spikes will stop
the components sliding out of alignment as you clamp up and won't show on
the finished job.
When countersinking, run the drill in reverse - this avoids chatter and the
star-shaped countersink holes that everyone's experienced.
Keep a stump of candle in your screwbox and drag each screw thread over it
to lube it before you fit the screw - everything goes a lot easier, and the
screw won't rust into the hole so readily. You'll drive a lot more screws
with one charge of your drill-driver, or save a lot of fatigue if you're
driving the screws manually.
If you're putting in brass screws, run in a steel screw first, first, then
remove it and fit the brass screw. Much less chance of snapping the brass
screw or marring the slots.
If you want to be really traditional, accurately line up the slots in all
the screws in the along-grain direction. My old Master, Sid Porter used to
reckon it was the difference between a tradesman and a craftsman.... Not
that it matters if you're plugging the holes!
Outgoing mail is certified Virus Free.
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friend who was not mechanically inclined asked why all the slots were that
way. I explained that the screws heads were magnitised and they stopped when
lined up with north and south poles. He bought it. W W
Definitely. Then I'd do a dry assembly with enough of the screws
inserted one or two turns to hold it vaguely together.
Then check that the legs are on the right way up, the drawers fit the
right way round, and the left side is the same size as the right. It's
not good to discover this stuff, but it's better than finding it out
once the glue is wet.
I rarely screw carcases together. If I am using screws, chances are
that it's workshop trestles or something. For this sort of work, a
one-piece pilot, clearance and countersink bit is a great help. You
can do the whole hole in one pass, after the glue is on and the first
"Norm screw" (just holding it while the glue dries) is in place.
What type of screws are you using? Pocket screws are my favorite. Drill
first, glue & assemble, square it up, screw. Using a right angle edge on
my formica topped assembly table makes it much easier, IMHO.
As someone who, as a beginner, got a few drill bits bound up in wet
glue, I'd say drill all your holes 1st, preferably on a drill press..
Though with the modern glues and the (ducking) biscuit, I rarely use
screws for assembly...
Another benefit of drilling 1st is that if you're gluing up something
that won't hold still while clamping, you can use nails dropped in a
few screw holes to align the parts...
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