Replies

1. 
   oldusty | May 18, 2007 01:54am | #1

   Bob,

               If the edges and ends are not square cut and milled squarely they can creep and move . I don't use the Kreg , but I use the pocket screw system and clamp them face down to glue and assemble . Ideally any discrepancy will be on the back side , in real life sometimes its on the back and sometimes its on the front . Can't tell if you're doing any part of it wrong from your description .

                       regards             dusty

2. 
   JMartinsky | May 18, 2007 02:41am | #2

   Dear Bob,
   I first used the PC production pocket cutter and then the Kreg. The difference that I noticed is that with the PC, I almost never get misalignment, where as with the Kreg I get misalignment about 40% of the time. That is after abandoning the Kreg clamp in favor of a Jorgensen type. Before that I was at about 90% misalignment. The Kreg jig is good, but it has two short comings:
   1) The angle that the screw is at is too steep, therefore, it tries to pull the pieces slightly out of plane.

   2) The Kreg jig does not provide a full pilot hole. When the screw exits, it pushes a slight amount of material out with it, thereby separating the two pieces to be joined, and then with the steep angle of the screw it then pulls the pieces out of plane while drawing them together.

   I now use the Kreg quite often and have learned to live with this "quirk", but try a different clamping method and see if that improves your joinery.

   Best,

   John

3. 
   mapleman | May 18, 2007 03:15am | #3

   Bob,

   To add to what John said about the kreg jig not drilling all the way through:

   I drill within 1/16th of the end grain, and then push the remaining wood out with a scratch awl before driving the screws.

   I also noticed some mis-alignment on my joints, however, it was usually the same part out of alignment over and over again. So I don't put the clamp pad directly over the joint, I put it about 75-80% over the part that is consistently "lifting up" and use fairly stout clamp pressure. Also make sure your screws holding the bench clamp plate are not pulling up - I had a problem with that as well and had to use some beefier screws.

   Good luck,

   Lee

4. 
   xmike | May 18, 2007 04:23am | #4

   Forgive me for stating what may or may not be obvious, but the show face must be down on the plate when the joint is clamped (or down on the round face of the portable clamp if that is being used) in order for the two sides of the show face to remain flush.

   SINCE YOU'RE ON THE JOB, HERE'S THE SHORT ANSWER

   1. set the drill bit stop so that the joint face is penetrated by the tip of the bit (you want a little hole in that face when you've drilled it).
   2. pre-assemble the joints dry (no slippery glue), treating this as a "dry assembly" step to verify that everything is flush and where you want it to be, then disassemble.
   3. reassemble with glue, making certain that you align things so that you are reusing your predrilled screw holes.

   Now the long answer:
   My experience also confirms that while not everyone has this problem, or alternatively, while not everyone cares about what they consider to be slight movement easily sanded or planed away, those of us that have experienced it (and care) conclude the following:

   1. The steep angle of the Kreg Jig does indeed seem to contribute to pulling one face out of alignment with the other. THE LUBRICATING EFFECT OF GLUE ON THAT JOINT MAKES THIS PROBLEM MUCH WORSE.

   Now I've been told all my life that the glue surface on butt joints is so weak, due to the end grain to long grain interface, that glue in such a joint is a gesture, only.

   If this is so, eliminating the glue at those joints should help the movement problem, without really weakening the joint. I can't help myself - I use glue anyway, but I get around this problem by preassembling and prescrewing the joints dry.

   (Other folks have bypassed these steps by purchasing a non-kreg jig that drills at a less steep angle.)

   2. When set by Kreg's directions, the relatively short length of the tip of their stepped drill bit fails to penetrate the joint face. Regardless of what kreg says, I and others have observed that this sometimes causes material to push out into the joint space as the screw is set, forcing a temporary bridge, which, when crushed as the screw is pulled tight, contributes to (causes, to my judgement) joint movement. I've been assured that the self tapping nature of kreg's screws obviates this problem. In my and other's experience, it does not.

   After some experience, I and others set the drill bit stop so that the bit penetrates the joint face. This definitely helps!

   The potential downside to this deeper setting is that it reduces the amount of material between the screw head and the joining face, potentially reducing the strength of the joint. I haven't noticed any of my joints pulling apart, however.

   To summarize, what to do?

   For me, when I absolutely, positively need the show face to remain flush,

   1. I set the drill bit stop so that the joint face is penetrated by the tip of the bit to eliminate the potential for joint movement as a consequence of temporary bridging.
   2. I pre-assemble my joints dry (no glue), treating this as a "dry assembly step" to verify that everything is flush and where I want it to be before I add the glue. When I do this step in conjunction with step 1., I seem to eliminate joint slippage due to glue in the next step.
   3. Then, I reassemble, using glue, being very careful to put things back together using my predrilled screw holes (key step).

   Hope this helps.

   Mike D

5. 
   MikeHennessy | May 18, 2007 02:06pm | #5

   I've never used the plate clamp, but I've never had any problem with face alignment using the vice grip-like hand clamps.

   Mike Hennessy
   Pittsburgh, PA

6. 
   Dave45 | May 18, 2007 04:38pm | #6

   I use the Kreg system and seldom see the problem you describe.  I think that my "success" can be attributed to:

   • I make sure that my end grain cuts are square and smooth in both planes.
   • I have my step drill adjusted to slightly penetrate the ends of the boards.
   • I do my assembly face side down on a flat work bench and I keep the surface clear of sawdust and small particles.
   • I have ~2" of overhang on my bench top and I clamp the joint to the top.
   • If I have a slight difference in stock thickness, I pad the joint when I clamp it.
   • I don't push very hard on the driver when I run in the screws - let the screw do the work.
   • I set the drill clutch to about 10 - 12, depending on the material I'm working with.  I want the screws to give me good clamping pressure without trying to pull completely through (which can mess up the joint).  This also prevents breaking off a screw head. (Guess how I figured that out?? - lol)

   I figured all of these out during the first few days of using my Kreg system.  At first, dialing back the clutch setting was just to prevent breaking off a screw, but then I realized that overtightening the screws could also distort the joint.

7. 
   MSS325 | May 18, 2007 06:19pm | #7

   I found that for me what works best is not using glue and not over tightening the screw. I use a very low clutch setting on my driver. If the stock is properly prepared the screw only needs to be snug. Any tighter I get the mismatch. Sometimes I'll use a handdriver after the screw gun just to make sure things are snug.  

1. 
   brookhillBob | May 28, 2007 06:57pm | #8

   Thanks to everyone for their input.  Utilizing many of your suggestions I came up with a procedure that worked about 80% of the time with the face clamps.  I drill so the bit just exits the surface and clamp the two pieces with another piece of wood ( 3" x 6") between the clamp and the face.  On the pocket hole side I used a small piece of copper under the clamp on the receiving board to provide an offset so when the screws pulled the boards out of alignment they ended up flush.  I also turned down the clutch setting on my drill/driver to 12 and dry assembled everything.  Even with the dry assembly step first, the glue still lubricated the joint to the point of some offset as opposed to the dry assembly.

8. 
   CallMeChaz | Apr 13, 2022 08:07pm | #9

   Sprinkle a tiny bit of fine table salt on one side of the glue. Joint no move. Even works on super-slippery, big, flat glue joints when clamping.

9. 
   _mj_ | Apr 13, 2022 08:22pm | #10

   Chaz, he solved his problem 15 years ago.