Have you ever built a seating bench or a chair using a Kreg Jig pocket hole system and wondered, how much weight can this bench hold? When working on my DIY projects, that thought always crosses my mind. What if someone sits on that chair that I build and that chair just crumples to the ground? That would be really embarrassing. So I did some research on how strong are pocket hole screws and this is what I found.
According to a study conducted by the RADCO testing division, a common 90-degree pocket hole joint using a 2×4 rail that is attached to a 4×4 post could hold 1361 lbs before failing. However, using the same setup, if you apply pressure from the bottom of 2×4, the same side as the holes, this 2×4 holds only 410 lbs.
When it comes to woodworking, not all screws are created equal. The type of screws to use will depend on situations, and some can be cheaper and easier to use than other types.
What are Pocket Hole Screws?
A pocket hole is, in a nutshell, a hole drilled at an angle that forms a “pocket” for the screw. The pocket hole is an advanced and precise toe-nailing that involves the pocket hole jig, which allows us to drill into the wood at an angle to produce the pocket to house the screw head.
The pocket hole screws, on the other hand, are designed as a joint between two adjacent boards. The idea is to have both boards to have the angled pockets drilled to them to hide the screws from sight. Since the screw must hold the two boards together at the joint, this whole system must be sufficiently secured.
Why Use Pocket Hole Screws?
The pocket hole screw system is especially important in DIY projects because the pocket hole screws allow very strong joints but the process of creating it is fairly simple. You don’t need any expensive tools or learn special skills for this: all you need is a Kreg jig you can use to drill angled holes on your wood to house the screws securely,
There are other techniques you can use to secure two different boards from dovetails, half-lap joints, and biscuits, among others, but most of these other techniques are typically time-consuming and would require expensive tools to make.
If woodworking is not a full-time job, then using pocket hole screws are the easiest and the most cost-efficient method. Also, pocket hole screws are strong enough to hold the board together, and you won’t need to use clamps (which can be quite expensive).
How Strong Are Pocket Hole Screws?
Below, I include a chart to display the strength of pocket hole screws based on our test using 4×4 (Post) and 2×4 (Rail) pieces with four different methods/joint types and three different screw positions for each method. This chart was based on a Kreg Jig Tool Company test conducted by the RADCO testing division.
As you can see from the image, there are four different joint types of pocket hole screws. Each joint was assembled as a Post (4×4) and Rail (2×4) system. Each configuration was tested with Cedar lumber as follows:
- Type 1: the Post and Rail form a 90-degree angle with two pocket holes. The short sides of the Rail sit flush to the sides of the Post.
- Top Pressure: force is applied to the long side of the Rail (opposite to the pocket holes), can hold 1,361 lbs of pressure
- Side Pressure: force is applied to the shorter side of the Rail, can hold 1,196 lbs of pressure
- Bottom pressure: force is applied in a similar way to the top pressure, but the force is applied to the same side as the hole, can only hold 410 lbs
- Type 2: the Post and Rail are positioned in a similar way to type 1, but the Rail is rotated 90 degrees lengthwise:
- Top Pressure: force is applied to the long side of the Rail (opposite to the pocket holes), can hold 1,325 lbs of pressure
- Side Pressure: force is applied to the shorter side of the Rail, can hold 1,025 lbs of pressure
- Bottom pressure: force is applied in a similar way to the top pressure, but the force is applied to the same side as the hole, can only hold 460 lbs
- Type 3: the Post and Rail form a T-shape with one pocket hole positioned on the opposite sides of the post.
- Side Pressure: force is applied to the short side of the Rail, just below the Post. Can hold 1,154 lbs
- Bottom Pressure: uplift force is applied to the Post from the bottom, can hold 1,025 lbs.
- Type 4: the Post and Rail form a T-Shape, with two pocket holes positioned on the opposite sides of the Post:
- Bottom Pressure: uplift force is applied to the Post from the bottom, can hold 1,961 lbs.
About Kreg Jig
Kreg Jig is a proprietary eponym or generic trademark to actually describes pocket hole jig because the brand Kreg makes the most popular jig on the market today. So, understand that when people say “Kreg jig”, it usually refers to the pocket hole jig.
A pocket hole jig, as briefly discussed above, is a tool that is used to create a pocket in a piece of wood where we can then attach a screw to join two boards together. The Kreg jig can guide your drill bit to the right angle and can be moved quickly from spot to spot, so they are very versatile.
Every Kreg jig contains at least these essential components:
- A drilling guide: The drill guide holds a bit at a proper angle for drilling pocket holes.
- A stepped drill bit: A 3/8″ drill bit with narrower tip.
- Depth collar: The depth collar is used to set how deep you want the hole to be drilled
- Long drive bit: For screwing-in the screws
Using a Kreg jig, we can quickly drill and attach all hole joints faster than with other methods, in general, it would only require 30% of the time it would take using other methods like biscuits or dovetails. Also, Kreg jig allows us to attach the boards using pocket hole screws that are stronger than merely gluing the boards together (as discussed in the above section).
However, that’s not saying the pocket hole joinery using the Kreg jig doesn’t have any downside. First, they need specialized screws to fit the pocket hole, and the process will leave a hole on the boards that might not be aesthetically pleasing.
Different Types of Kreg Jigs
Kreg is, as mentioned, a brand that produces pocket hole jigs, and they actually offer several different Kreg jig products, namely:
- Kreg Jig Foreman: for small to large scale projects (up to 75+ pocket holes) with built-in clamping, storage, and high-speed pocket holes feature
- Kreg Jig K5: for small to large scale projects (25-50 pocket holes) with built-in clamping and storage
- Kreg Jig K4: for small to large projects (25-50 pocket holes)
- Kreg Jig R3: for small projects (10-25 pocket holes)
- Kreg Jig HD: for outdoor small-large projects (1-100 pocket holes)
Choosing The Right Pocket Hole Screws Length
You can use this chart below to choose the right screw length according to your board’s thickness:
- 3/4″ and 1″ screw lengths are for 1/2″ material thickness
- 1 1/4″ screw length is for 3/4″ material thickness
- 1 1/2″ screw length is for 1″ material thickness
- 2″ screw length is for 1 1/4″ material thickness
- 2 1/2″ screw length is for 1 1/2″ material thickness