Pocket hole joints can move out of alignment when driving pocket screws. Using clamps is the best way to keep workpieces in position when assembling projects.
You may also enjoy these 9 Solutions to Common Pocket Hole Problems.
I’ve received a handful of messages lately from DIYers about an issue they’re having with their pocket hole joints. The issue is their joints move out of alignment when they begin to drive the pocket screws into the workpieces.
Daniel: How do I stop parts [from] creeping out of alignment when assembling?”
Marek: My biggest problem is that when I tighten, one of the two pieces moves up a bit.”
Orhan: I have difficulty in keeping the pieces to be joined by pocket screws in alignment. The torque that the screw conveys to the wood makes it difficult to maintain my initial alignment. Using glue makes the surfaces further slippery.”
I know exactly what these DIYers are talking about. I’ve had this same issue myself when I first started building projects with pocket hole joinery. Let’s look at why workpieces can move out of alignment when assembled with pocket hole joinery and how to prevent it.
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Why Pieces Move When Assembling Pocket Hole Joints
I think it’s important for us to look at other types of joinery to understand why pocket hole joints can move out of alignment when they’re being assembled. Let’s take a look back at the Kreg Jig vs Biscuit Joiner tutorial where we compared and contrasted the differences of pocket holes and biscuit joints.
Related: Kreg Jig vs Biscuit Joiner
Biscuit Joints Keep Faces Properly Aligned
In the Kreg Jig vs Biscuit Joiner tutorial, we looked at how a biscuit joiner or plate joiner works. The biscuit joiner has a small horizontally mounted saw blade. The biscuit joiner is plunged into the edge of a workpiece and the blade cuts a half-moon shaped slot. Then the biscuit joiner is used to cut the second half of the slot on the corresponding workpiece.
Glue is applied to a thin football shaped wafer called a biscuit. The biscuit is placed into the slots and the joint is clamped until the glue dries.
The biscuit keeps the faces (or the top and bottom) of the workpieces flush and prevents the pieces from moving out of alignment while we’re assembling our project.
Pocket Hole Joints vs. Biscuit Joints
A pocket hole joint works differently than a biscuit joint. A Kreg Jig or pocket hole jig uses a guide block with preset holes to drill angled pocket holes in a workpiece. A pocket screw, specifically designed to be used with pocket holes draws the two workpieces together to form a strong joint.
The biscuit prevents a biscuit joint from coming out of alignment while it’s being assembled. There isn’t anything to prevent a pocket hole joint from coming out of alignment while it’s being assembled. In fact, driving the pocket screw can actually force the workpieces out of alignment.
How to Prevent Pieces from Moving When Assembling Pocket Hole Joints
Now we understand there isn’t anything to prevent our workpieces from moving out of alignment when assembling our pocket hole joints. So is there anything we can do to limit or prevent this movement? Absolutely. We can use the mechanical advantage of clamps.
Don’t Hold Pocket Hole Joints with Your Hands
I know what you’re asking yourself. “Do we really need to use clamps? Can’t we just hold the joint with our hands?” The answer is no. We NEED to use clamps!
Using Your Hands is Dangerous
The first reason we want to use clamps instead of holding a joint with our hands is that it could be dangerous. Skate over to the comment section of the 9 Pocket Hole Mistakes You Don’t Want to Make tutorial if you don’t believe me. There you’ll read Scott C’s comment:
Here is a mistake I don’t want to make again. Never hold the joint with your hand as you drive in the screws. The driver tip slipped on me and drove into my palm of my hand. It hurt and I went to the doctor and after an xray they cleared me of any broken bones, but this is very easy to do. Use a clamp to hold together for safety.”
Handheld Joints Come out of Alignment
The second reason we don’t want to use our hands when joining pocket hole joints is that the joint will come out of alignment. I know some people may disagree with me because I’ve watched videos of DIYers who assemble pocket hole joints without using clamps.
I have tried to assemble pocket hole joints without using clamps. The joints always come out of alignment and the faces of those joints are never flush. Sure, you can assemble without clamps, but that means those joints will require a lot of sanding to get the faces flush. It’s so much easier to properly clamp the joint in the first place and avoid all of that extra sanding.
The bottom line is our hands can’t grip as tightly as a clamp. Try as we might, we can’t beat the mechanical advantage of a clamp. Using clamps when assembling our pocket holes means our joints will be tight, stay properly aligned and ensure our DIY projects will look professional.
Face Clamp Keeps Faces Flush
One way to keep pieces from moving when assembling pocket hole joints is with a Face Clamp. The face clamp keeps the faces of workpieces flush while driving pocket screws.
Right Angle Clamp
A second way to keep pieces from moving when assembling pocket hole joints is with a pocket hole clamp or a Right Angle Clamp. One pin on the Right Angle Clamp fits into the pocket hole and the pad rests on the other workpiece. The clamp applies pressure to the joint and draws the two workpieces together.
Face Clamps and Right Angle Clamps are great for assembling one joint at a time. And I have Face Clamps and Right Angle Clamps in my workshop but I prefer to clamp my entire assembly rather than clamp one joint at a time.
My favorite way to clamp my entire assembly and keep parts from moving out of alignment when assembling pocket hole joints is by using an assortment of bar clamps.
First, I lay out the assembly according to my plan. In the example below I’m clamping the side assembly for my DIY vanity. Then, I use bar clamps to tightly hold the pieces in place. Using this clamping method prevents any movement while I drive my pocket screws.
Clamping the entire assembly also ensures that every joint is properly aligned to the other joints for that assembly.
How to Clamp Pocket Hole Joints
In the 6 Tips to Clamp Your DIY Project Like a Pro, we talked about how there is a science to clamping.
Related: How to Edge Join with Pocket Holes
When we use a clamp, like a bar clamp, it exerts force in a 45-degree angle to the left and to the right from where the clamp contacts the wood. We need to position the clamps so the same amount of force will be applied along the entire workpiece.
But wait, there’s more. We should also alternate the position of our clamps from the top and bottom of the workpiece. This will ensure the same amount of pressure is being exerted from side to side and top to bottom.
Use Clamping Cauls
In the How to Decide What Scrap Wood to Keep tutorial, I shared that I keep some scrap wood on hand to use as clamping cauls. Clamping cauls help the clamps exert an equal amount of pressure when clamping and they also help to prevent damage to our DIY project.
Cauls protect the wood when clamping our project. The cauls are placed between the clamps and our project so the clamps will dent the cauls, not our DIY project.
Use Wood Glue
I’ve shared in many of the pocket hole posts that I’m a big advocate of using wood glue with pocket hole joinery.
I think wood glue makes a strong pocket hole joint even stronger, but I believe it can also help to prevent pieces from moving when assembling pocket hole joints.
At the beginning of this post, Orhan said: “Using glue makes the surfaces further slippery.” This is true. Too much glue can make joints slide out of alignment, but I believe applying “just the right amount of glue” will actually make the joint “sticky”.
How Much is the Right Amount of Glue?
How much glue should we apply to a pocket hole joint? We need a little glue “squeeze out” when we assemble a joint. I know this sounds crazy but it’s called “squeeze out” when we apply glue to a joint and the glue squeezes out when the joint is pushed together.
If we don’t have squeeze out when we assemble our joint it could mean we have a “dry joint” which means there isn’t enough glue to secure the joint.
What we need is what I refer to as the glue “sweet spot”. We need enough glue to prevent a dry joint and not so much that the glue is erupting out of the joint like a volcano!
I can’t tell you what the sweet spot is because it’s different for each joint. But what I will share with you is how to achieve the glue “sweet spot”.
First, we’ll apply a little glue to our joint and use a spreader to evenly coat the joint with glue. Next, we’ll bring the workpieces together and rub the joint back and forth (like we’re rubbing our hands together).
If we have just the right amount of glue the pieces will stick together. It will almost feel like the glue has suction like a vacuum. Then we’ll clamp the joint and have just tiny little “boops” of glue along the joint. Yes, “boops” is a woodworking term!
That’s it. We just created the perfect joint. It takes some practice to get to the glue “sweet spot”, but give it a try. I know you can do it!
Use Pocket Screws
The last tip I want to share with you is to always use pocket screws when assembling pocket hole joints.
Pocket screws are designed differently than a typical wood screw. Pocket screws (left) have threads only on the lower portion of the shank and the upper portion is not threaded. Wood screws (right) have threads along almost the entire length of the shank.
The design of a pocket screw allows it to slide through the pocket hole and drive into the other workpiece which pulls the joint tightly together.
The threads of a wood screw won’t allow the screw to slide through the pocket hole which may not pull the workpieces tightly together. Using a wood screw in a pocket hole could cause loose-fitting joints or even worse a wood screw could crack the board.
Pocket hole joints can move out of alignment when driving pocket screws. Using clamps like Face Clamps or Pocket Hole Clamps will hold the workpieces in position. My favorite way to prevent workpieces from moving is to clamp the entire assembly with bar clamps.
Thank you for stopping by. If you found this information helpful, would you please pin it to Pinterest? Other DIYers would appreciate it and I would too! Thank you – Scott
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