How to Join Different Thicknesses With Pocket Holes
Stumped with pocket holes and different board thicknesses? I’ll show you the right jig to use and a simple trick to join them without screw blowouts.
Wondering how to join a thicker board to a thinner one without driving the screw out the other side or not going in far enough? I’ll walk you through the process, which jig to use, and a simple trick to remember when joining different workpiece thicknesses.
Originally published April 3, 2018, republished September 23, 2024.
Table of Contents
- The Challenge of Different Board Thicknesses
- Simple Trick for Joining Different Thicknesses
- Which Pocket Hole Jig Should You Use?
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The Challenge of Different Board Thicknesses
I’ve been getting messages from DIYers like Riaz, Roy, and Jackie struggling with a common problem: joining different-thickness workpieces with pocket holes.
Riaz plans to “join pieces of different thickness” and wondered how to set up the drill guide, the drill bit depth collar, and what size screws to use when joining them.
Roy wants to join a ¾ inch workpiece to a 1-½ inch one and would like to know what size screw to use.
And Jackie asked:
I am building a desk out of 2×4s. The instructions say the end pocket holes will have 2-½” screws, and the pocket holes on the long edges will have 1-¼” screws (to attach to 1×6). I have the K5, so I set my block for 1-½” thickness, but when I set my drill bit depth to 1-¼” screws, it takes my collar too high on the drill bit. Am I doing something wrong? I had to remove the collar to make it work.”
I’ve been there. Joining materials of different thicknesses with pocket holes can be a real head-scratcher. If you don’t set up your pocket hole jig correctly, the screw won’t go in far enough, or it will drive right through the second workpiece.
Let’s talk about joining different thicknesses, a quick trick to remember how to set your jig, and which tool is best for the job.
Simple Trick for Joining Different Thicknesses
When I’m drilling pocket holes to join materials of different thicknesses, I always remember this simple phrase, “think thin,” meaning I adjust the drill guide, drill bit depth collar, and use screws to match the thinnest piece I’m working with.
Related: How to Use a Pocket Hole Jig (& Beginner Pitfalls to Avoid)
Using Jackie’s scenario, let’s look at joining a 2×4 to a 1×6.
Set the Drill Guide
When joining a 2×4 to a 1×6, remember the “think thin” rule. Adjust your pocket hole jig and use screws for the thinner board, which is the 1×6.
Since a 1×6 is actually ¾” thick, adjust your drill guide for ¾” material.
Related: Beginner’s Guide to Wood Sizes
Set the Drill Bit Depth Collar
When setting the drill bit depth collar, again, you’ll use the “think thin” rule, adjusting your depth collar for the thinner board, which is the 1×6.
Because a 1×6 is actually ¾” thick, adjust your drill bit for ¾” material.
Then, drill the pocket holes.
Choose the Screw Length
Let’s review what you’ve done so far:
- Adjusted your drill guide and depth collar for the 1×6, which is the thinnest material at ¾”.
- Drilled the pocket holes in the workpiece.
Next, you’ll attach the boards, and again you’ll use the “think thin” rule, choosing pocket hole screws for the thinner board, which is the 1×6. For a ¾” thickness material, 1-¼” pocket hole screws are the recommended length.
Related: How to Prevent Workpiece Movement in Pocket Hole Assemblies
Which Pocket Hole Jig Should You Use?
When I first wrote this article in 2018, you could use almost any jig to join different thickness materials. Since then, auto-adjusting jigs like the Kreg Jig 720 have come on the market, automatically adjusting to your workpiece’s thickness.
Related: How to Use a Kreg Jig 720
Auto adjusting jigs are quick to use and guarantee an almost goof-proof setup, but they present a challenge when you need to “think thin” when joining different thickness materials because they automatically adjust to your thickest board.
If you have an auto-adjusting jig, like the Kreg Jig 720, and need to join different thicknesses occasionally, I recommend picking up the Kreg Jig Mini. It’s an easy and affordable solution.
Related: How to Use a Kreg Jig Mini
If you frequently need to join different thicknesses, you may want to consider buying a Kreg Jig 320 or 520.
Related: Which Kreg Jig Should You Buy? (Here’s the Answer)
Final Thoughts
Joining thicker and thinner boards with pocket holes can be challenging, but when you “think thin,” it’s a breeze. By adjusting the drill guide, drill bit depth collar, and using screws to match your thinnest workpiece, you’ll be able to create strong, durable joints that will enhance your woodworking projects.
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All these tips are great if you have the latest and greatest Kreg jig kit or device, but doesn’t do anything for the much older Kreg jig that is one l-shaped piece of metal.
Unless I missed something in my quick read.
But all I all good info.
Thanks, Tim
Hi Tim – These tips are applicable for all Kreg Jigs, so your jig will work just fine.
Problem is there is no adjustment on the old metal Kreg body, like adjusting for different thicknesses as you talked about. It is all guess work and trial and error, practicing on scrap first. So no your artical doesn’t really v
Fit the older metal bodies.
Thanks for the replie,
Tim
How do you know the size of the screw to use? I want to screw 2×4 to 4×4.
Hi Mike – Thank you for stopping by. To attach a 2×4 (which is 1-1/2″ thick), you’ll want to use a 2-1/2″ pocket screw. Also, I have a handy wood thickness/screw length chart in the 9 Pocket Hole Mistakes You Don’t Want to Make Post.
Can we take a different example, and see if I’m looking at it right? Let’s attach a 1x shelf to a 1x side. According to the Kreg website, you should use a 1-3/4″ screw. That is straightforward, since both are the same thickness.
If you swap the side with a 2x board, the hole in the shelf wouldn’t change, but you can use a longer screw.
So, in my mind, if you are attaching a 1x shelf to a 2x side, you would do the hole based on the 3/4″ thickness of the shelf, no matter what the thickness of the side. But you could use a screw anywhere between 1-3/4″ and 2-1/2″ (adding the extra 3/4″ for the thicker side).
Would this line of thinking give you the correct results?
You mention “think thin” but the picture shows pocket holes in the 2×4. I would swap the picture with one that has pocket holes in the 1×6
Hi Chris – Thank you for stopping by. “Think thin” refers to settings on the jig not which workpiece has the pocket holes drilled into it. You can drill pocket holes in the thicker or thinner workpiece as long as the jig is set for the thinnest material you’re working with.
A handy tool that Kreg has is the Selector Wheel. It lets you dial in the thicknesses of the wood being used and tells you how to set up your Kreg Jig and also what length screw to use. It can be purchased at the Kreg website or Amazon.
Hi Michael – Thank you for stopping by. I agree with you… that selector wheel is handy!
In the K5 example, how come you didn’t set Drill Bit Depth Collar to 3/4″ like for the Kreg Jig Mini, Kreg Jig R3 and Kreg Jig K4, but rather for the K5 you set it to 1 1/4″ ?
Hi Guy – The set up for the K5 is a little different than the other Kreg Jigs. The drill guide is set for the thickness of the material, but the drill be is set for the length of the screw you will be using.
I cannot find the answer to this anywhere, so I am going to ask you. I want to attach a 1.5″ x 1.5″ support rail to a 3/4″ plywood wall, about 15″s from the floor. What length screws should I use please? I will be making hte pocket holes in the 1.5 x 1.5 and screwing into the 3/4′ plywood and do not want to go all the way through to the other side of the plywood.
Thanks for any guidance,
Hi Gypsy – Thank you for stopping by. The rule for joining different thickness materials with pocket holes is “think thin”. In other words, adjust the settings for the pocket hole jig to the thinnest material you’re working with. The thinnest material you’re working with is ¾” plywood. A 1-¼” pocket screw is used to join ¾” material. So you’ll use a 1-¼” pocket screw for your project.
That said, it’s important to note that ¾” plywood is often thinner than ¾”. When using pocket holes on plywood it’s a good idea to set the drill bit so that it doesn’t drill the pocket hole as deep as it normally wood. It’s also a good idea to try your set up on some test pieces to be sure everything is adjusted correctly before drilling the pocket holes on the pieces for your project.
I want to butt join a 3/8” thick piece of walnut to a 3/4” Thick piece I would be angle drilling the 3/8 piece and pirercing the 3/4 piece using the smaller head screws. Have you done this or will the 3/8 piece be too “thin” after the hole is drilled at the end of the board or will the angled hole drill completely through the 3/8 piece?
Hi Fred – The thinnest material you can join with pocket holes is 1/2″. So this 3/8″ material would be too thin to join with pocket holes.