Technical - Workshop Notes
“Robertson's Screws can be your best friend for joinery”
It wasn't till recently that I realised there are two types of woodworkers: Those that have absolute joy using Robertson screws on their projects, and the rest of us that swear at cracked timber and poor joints. Actually, I lie, there are three types, there's me, who had the opportunity to listen to Robert Low from local ScrewIt Screws in FTG, years ago when he came to show us his range of Robertson screws. At the time, my projects didn't involved joinery, and the good oil in his message slipped through the cracks, so to speak.
Well then roll the clock forward some years, and my Son introduced me to Pocket Hole tools for making hidden angled joinery, which requires three important features in a screw, to ensure a firm reliable joint, as well as an ability to easily unscrew and rejoin during assembly work.
The secrets of ROBERSTON Screws
- a washer based flat underside to the screw head, so that the screw bottoms out, and pulls the second piece of timber up firm to the base of the first piece where the screw has entered.
- a decent square socket in the head of the screw, avoiding 'cam-out' (stripping of the driver slot)
- a self tapping, tapered end to the screw, ensuring that the underlying second piece of wood does not split, as the point of the screw beds in.
AVOID TIMBER SPLITS
By comparison, so many screws are flat topped, with countersunk heads for sitting in a countersink hole, often with a phillips head cross slot. The problem is, if the screw is over tightened into the countersink, then the conicle shaped underside of the screw head forces deeper into the top board, often splitting the hole wide open and destroying the important, top showing piece of wood. That one mistake can cost you more in replacement timber and lost time, than the small price for paying for better screws. I know this, from my annual reconstruction of Xmas decorations where attempting to re-screw a frame kit with wrong screws, has split most of the joints now. Yes, I'm a slow learner obviously.
WALLMATES for affixing with no studs
But recently a project that required affixing timber sheets to a wall with no studs, presented another challenge. But enter the WallMate, a brillant item for such issues. Armed with the special pocket hole drill that has a small tip drill coupled with a counterboring drill (not countesinking!), the opportunity arose to combine the use of Robertson screws in a counterbored hole though to a WallMate in the plaster - brilliant!
COUNTERBORING instead of COUNTERSINKING
The use of counterboring (see the example in picture below), provides a recessed hole for the head of the Robertson screw, but with a flat base, which means the screw can penetrate into the WallMate, and screw in until the base of the Robertson head reaches the counterbored surface, and pull the sheet hard up against the WallMate. All that is required first, is to ensure the WallMate is flush with the surface of the plaster wall when putting that in.
The reason for having the counterbored hole, rather than just allowing the underside of the Robertson screw to rest against the flat surface of the sheet, was becuase I wanted to hide the screw. The project involved putting a 2-pac MDF sheet vertically against the wall, with a cleat for supporting a horizontal shelf. Placing the WallMate hole just above the cleat, meant that when the shelf was slid over the cleat, the counterbored hole became hidden behind the edge of the shelf. So the whole project appeared to be screwless.
POCKET HOLE TOOL
As for Pocket Hole equipment, that's another story, but it invovles the use of the special features of Robertson Screws. When your project needs to join say, 2 pieces of 18mm MDF at right angles, like making a box for instance, you may want to hide the joinery screws. A Pocket Hole tool allows you to drill a hole (or two) at a really steep angle on the hidden side of the joinery, and place Robertson Screws deep into the pocket hole, pulling the two pieces of timber together really firmly (A small example picture below) Assembly can entail preliminary joining, and checking, and then unscrewing, glueing and re-joining. Hence the need for a reliable, virtually unstrippable screw head. The ideal tool here is a #2 Robertson Head square drive bit that is really long for angled usage, on a hex shaft for use in a quick release power torque drill.
FINE or COURSE thread?
For softwoods, like MDF, use a course thread screw. BY comparison, if using hardwoods, then a fine thread is ideal.
For all your Pocket Hole screw needs, check out SCREWIT SCREWS located at:
10/756 Burwood Highway Ferntree Gully Victoria 3156
1300 551 810 (8am-5pm Monday to Friday)
An ideal kit (pictured at the top of this article) is their Pack-1 that comes with a square head driver
Take a moment to listen to their story at:
Happy woodworking! .... Gary Pope 0408994799