Pocket hole joinery offers a tremendously strong joint with a lot of clamping pressure. According to Kreg tools website, the joint does not require any glue. However, you feel so inclined adding a very thin bead of glue will only help to strengthen the bond. Since the joint uses a mechanical fastener, there is no need to clamp the wood after the screws have been driven in.
Following the instructions, clamp down the jig and drill the pocket holes into the stock. This is the easy part.
The interesting part is driving the self taping pocket hole screws into the stock. The drill bit does not cut a pilot hole on the other stock piece. The self tapping screw is supposed to cut its own hole. But depending on a few other factors does not always work as advertised.
In my application I was attempting to join two boards at 90 degree angle. The board that had the pocket hole cut into the pocket hole was running parallel to the grain. The board that it was going to be joined to the grain ran 90 degrees and screw was going to be about 1/2 inch to 3/4 of an inch from the end.
I was able to drive the screw about three fourths of the way in before the wood split (the board that the screw was being driven into, not the pocket hole board). Part of my problem is that I was just too close to the edge.
The next pocket hole was on the same receiving board about 24 inches in from the end with another pocket hole drilled board. The pocket hole drilled board was 2 1/2 inches wide and contained two pocket holes. The first screw went in nice and tight. The second screw went in and caused the wood to split again. This time the pocket holes were too closely spaced.
Another problem is the wood. The project was being built out of Honduran Mahogany from Brazil. I have had the rough cut lumber stacked up in my work shed for three years it is well aged and very dry. I am pretty sure that lumber that has a higher moister content will reduce the likelihood of splitting.
The other problem that I have had is getting enough clamping pressure to keep the two boards together while the screw is being driven in. A fair amount of force has to be applied to the screw and that has caused me significant problems in the two boards separating with up to a 1/4 in gap until the screw pulls the boards back together again. But during this time there is a good chance that the boards will slip just slightly out of place.
As I hinted to in the previous post, I have finally stumbled upon a clamp that should resolve this problem for me the ‘right angle clamp’. One end of the clamp has a 3/8 inch pin that fits into the pocket hole. The other end is a flat disk mounted on a 180 degree swivel. The clamp should keep the two boards together while the screw is being driven in. Perhaps I can find a used one on eBay for less than retail.
