Introduction: Silent Screw Technique
My late father taught me this technique for joining boards by the long edges, using 'silent' screws.
One can join several boards together sequentially, if for instance, one is making a table top.
One does not then need clamps for the actual joining, just while performing the technique.
It makes for a very strong joint - screws and glue together.
- Wooden boards.
- Quick release clamps.
- Tool to true the long edges - I use a jack plane.
- Marking out tools - Calibrated rule, tri - square and pencil.
- Cordless drill.
- Drill bits set.
- Screws. Steel Phillips head are fine. Adjust the screw size to the board thickness - thicker boards, heavier screws.
- Note: If joining oak boards, use brass screws. Steel screws will be eaten through in a year.
- Hammer or mallet.
- Scrap piece of wood.
- White glue.
True up the edges of the boards to be joined, so that when placed with the edges to be joined together, there are no gaps, and it is as you wish it to be when finished. I use a jack plane for this.
Decide, depending on the length of the boards, how many screws you will need. It is best to place the first ones about 5 cm (two inches) from each end of the board and then one every 20 cm, (8 inches) between.
It is not critical, you can place as many as you wish - do not place too few. For boards about one meter, (three feet approx.) long, I would place five screws.
Clamp the boards together, with the mating surfaces uppermost. Offset one of the boards a short distance, as shown in the photo above.
Mark across both boards with a pencil as shown.
Mark a line in the middle of the thickness of the boards as shown. One of them serves to show where the screw will go, while the other must be the same length as the offset (see photo above).
Drill a sequence of holes along the offset line. The diameter must be the thickness of the shank of the screw, plus a small amount for clearance.
Re-drill the hole on the cross line - the diameter must be that of the head of the screw, plus a small amount for clearance. ( see pic above). So, now you have what looks like a keyhole.
Repeat for all the holes.
Note: For really hard woods, (Oak, Wenge, Panga Panga , Iron wood etc) make the clearance amounts greater, but not so as to exceed the diameter of the screw head, since then the whole technique will not work.
This is so that it will be easier to mate the boards later (step 4), without bending the screw shanks.
Insert screws where the lines cross - see pic above.
Offer up the board with the screws to the one with the slots and check the fit. The boards should mate nicely with no gaps.
Use a hammer and a piece of scrap wood to drive the upper board, so that the butt edges line up. I will refer to this part as 'latching' from now on.
Check the fit again - the boards should mate nicely with no gaps. Adjust fit if necessary at this point.
If all fits well, unlatch the boards.
Tighten each screw a quarter turn. This will give a close fit when the boards are latched once again.
Apply glue to the mating surfaces and re-latch, using the hammer and the scrap piece of wood as before.
The boards re-latched - (First pic)
Allow to set. White glue begins to tack quite quickly.
All having gone as planned, the result is good ( second pic)
One can repeat with multiple boards, if necessary, if making a table top for instance.
I hope that you find this technique useful - have fun!!