OK, But Not As Good As I Expected
I purchased this drill guide several years ago intending to use it to build laundry room cabinets from 1/2 inch oak veneered plywood. I never completed this project but did do some tests on this drill guide. Now, I want to build a simple drawer out of ordinary 1/2 inch plywood so I brought out this drill guide to do more testing and refresh my memory.
First of all, I think that some of my concerns have to do with joining 1/2 material, especially plywood, in general. That said, I drilled a couple of test holes and saw that the drill had penetrated the bottom edge of the board. For "normal" pocket holes using standard screws, the bit does NOT come through if you have set everything up correctly. When the bit comes through, it, of course, makes a hole in your Kreg fixture. I was using the Kreg K4 setup and this was really of no concern because I already have a few "bullet holes" in my K4.
I then proceeded to attach the drilled piece to another 1/2 piece and the joint seemed sturdy enough. So why the penetration?
The drill bit collar had not been adjusted since I had last used it several years ago. The instructions that came with this guide say " To accurately set your depth collar, use the built-in depth gauge and instruction manual included with your Kreg system". So why didn't Kreg just SAY where to set it?
When I checked the collar setting against my K4 collar setup mark, it was somewhat longer than the "1/2" mark you might expect. So, I moved the collar back and set it to the "1/2" mark and drilled several more test holes. After attaching to another 1/2 board, I found the joint to be un-study. It seemed clear as to why. With the 1/2 inch setting, the screw, the recommended 3/4 inch size, only "sticks" out about 1/4 inch. And, then, the very end of the screw is "pointed" meaning even less area to grab.
Elsewhere in the drill guide instructions, it says "In order to create a 'pluggable' Micro Pocket hole in 1/2 material, set the collar for 5/8 inch material." Now, I didn't care about plugging the holes, but clearly changing the collar from the 1/2 inch setting to the 5/8 setting would result in more screw protrusion. So, I did this and testing again. The result was again a sturdy joint.
The screw was now protruding about 3/8 of an inch versus 1/4 inch. However, the screw was now, as expected, also coming out pretty close to the edge of the board.
While I didn't have any edge breakout, the concern is there. Also, since plywood is "layered", there is a risk of "pushing out" little fingers of wood. I remember this happening when I did my original testing.
I think one should consider which side of a board has the pocket holes to minimize the risk of edge breakout. Obviously, the emerging screw is angled and will trend toward one edge or the other. Assume you are joining two drawer corners, if you drill from the "inside", the screw will run toward the edge of the mating board. If you drill from the "outside", the screw will run away from the edge, reducing the chance of breakout. Maybe this is a "don't care", but, it may impact how you choose to build your project.
Here is a summary of my observations/recommendations:
If you can stand the increased weight, and perhaps cost, use 3/4 material and stay away from 1/2 inch.
If you have to use 1/2 inch, use solid wood instead of plywood.
If using 1/2 material, drill the pocket holes so that the screw will want to run away from the edge of the mating board.
Always set the collar to 5/8 inch if you're using this jig. You may want to play around with the "standard" Kreg drilling guide and screws and see if this works for you.
Glue the joints if using 1/2 material. (1 seldom do with 3/4 material).
Mark the collar of THIS drill BLACK so you don't confuse it with other drills. That way, you won't necessarily have to re-adjust the collar when switching between 3/4 and 1/2.
As usual, I found the quality of this Kreg tool to be excellent. More guidance, as I found by trial and error, would be appreciated.