Pocket Holes In MDF
MDF, or Medium Density Fibreboard to give it its official name, is a popular choice with many woodworkers because it’s smooth, consistent and budget-friendly. Likewise, pocket holes are a firm favorite with lots of folks who want a strong joint that can be hidden away so there are no unsightly screw heads visible on whatever it is they’re building.
At the same time though, both of these have plenty of detractors who say you should steer clear of MDF at all costs and it’s not ‘real’ wood or that pocket holes are not strong enough, or they ‘don’t count’ as real joinery, whatever that means…
So they certainly share some things in common but does that mean they go well together? Can you use pocket holes in MDF? Well, the short answer is yes, you can use pocket holes in MDF as long as you use the correct screws and don’t overtighten them. Pocket holes in MDF do work but MDF is not very forgiving with them and it’s very easy to make a mistake and ruin your project.
Do Pocket Holes Work In MDF?
Surprisingly, yes, pocket holes can work in MDF as long as the right type of screws are used and your technique is on point.
MDF is much less forgiving than other woods when using the pocket hole technique to join, but with a bit of practice and patience it is certainly doable.
If you do go down the pocket hole route, I’d recommend using course-threaded screws to really grab hold of the soft fibers in MDF and lessen the chance of splitting, and a nice sharp drill bit for the pilot holes to keep them as clean as possible.
And you’ll want to go VERY CAREFULLY when driving those screws so you don’t go straight through and come out the other side of your pieces!
What Is MDF?
MDF is an engineered wood product made by mixing fibers from other wood products with resin and compressing them into sheets before sealing them with heat.
The result is a strong, uniform board that has no knots or grain and is typically flat and smooth, making it easy to work with.
Despite having ‘medium’ in its name, MDF is actually heavier than plywood (and lots of solid woods) and certainly feels very ‘dense’ when you pick up a sheet of the stuff. Despite all that density though, it’s actually pretty easy to damage MDF sheets, particularly around the edges and corners so you’ll need to take care when handling or moving MDF around the workshop.
If you are careful with it though, you’ll soon find out why MDF is so popular to work with and why it’s probably the most used type of wood for cabinets in the whole world.
MDF boards are as flat as, well, as flat as a board really, and super smooth on both the front and the back. They are incredibly easy to work with and can be cut, drilled or routed just like solid wood but with no nasty surprises like hitting a knot or having that oh-so-annoying tear out happen just as you’re about to finish the final piece of your project!
Finishing MDF is a bit of a mixed bag – it accepts paint far better than other woods and the glass-smooth surface gives an outstanding final product, but you won’t get very far with a wood stain. Probably not the end of the world for most people when there’s no wood grain to accentuate but it does invariably mean you’re left with a choice between painted finish or the distinctly ‘mid brown’ color MDF is usually produced in that quickly gives away its identity.
What Are Pocket Holes?
Pocket holes are holes drilled partway into a piece of wood at an angle of around 15 degrees so that a screw can be screwed through that piece and into a second piece, joining them together.
Usually, you’ll also apply glue to the pieces being joined for extra strength and the pocket screw has the double effect of joining the wood together itself and acting as a clamp for the glue.
The beauty of pocket holes is that the screw head ends up hidden from view once it’s screwed into the first piece as it sits below the surface of the wood.
Depending on the application you can either leave the hole as-is or fill it with a dowel or plug and sand it flush. Once your finish is on the wood, chances are nobody will ever notice the join and wonder how you’ve created such a smooth and strong joint!
Pocket holes are typically used to join two pieces together at a 90-degree angle but can technically be used at any angle – I used pocket holes to join the sides and bottom shelf of this bench after cutting the edges at an angle.
Do You Have To Use Pocket Screws For Pocket Holes?
Technically no, you don’t need to use pocket screws for pocket holes and you can get away with using regular wood screws in ‘real’ (ie non-engineered) wood, BUT the joint will be stronger if you use the recommended pocket screws – that is what they are designed for after all.
And that goes double when working with MDF. Pocket screws definitely make a difference with pocket holes in MDF.
Whatever material you are using, at the very least you should use a pan head screw or something similar with a wide, flat bearing surface or there’s a very real risk that you’ll screw too deep into (or even straight through) the pocket hole and severely weaken the joint (or ruin it altogether).
Pocket Hole Jigs
What’s a pocket hole jig? Essentially it’s a guide for your drill bit to help you screw into the wood at the best angle for a pocket hole.
Are they necessary? Like with the screws, you can get away with free-handing it (like I did with the bench above) and just drill at an angle that feels right, BUT if you’re working with MDF I’d definitely go with a jig to make sure you get the optimal position and angle for your joint.
Jigs will usually come in a set with clamps for your workpiece and depth stops for your drill bit which make the whole process fairly idiot-proof which is a major plus if you’re working with MDF (or have a tendency to act like and idiot as I sometimes do!)
Are Kreg Screws Good For MDF?
If you spend any amount of time reading about pocket hole joinery you’ll hear the name Kreg over and over again because they are the market leader in all things pocket hole.
From jigs to screws, Kreg are synonymous with pocket hole joinery, and for good reason – they do it better than most.
Kreg screws are some of the best for pocket hole joinery so grab yourself a pack and get to work.
Tips For Using Pocket Holes In MDF
- Use a clamp and jig to position your pocket holes properly
- Don’t drill too deep with your pilot hole
- If your boards are different thicknesses drill your pocket hole in the thinner piece
- Use the right type of screw
- Glue the joint for extra strength
- Drive your screws in SLOWLY so they don’t go too deep
Downsides Of Pocket Holes In MDF
It should be clear by now but let’s just go over the downsides of using pocket holes to join MDF:
- MDF can split easily, especially when driving in your screws
- The surface of MDF can get damaged easily and weaken your joint
- Pocket holes are not the strongest joint and MDF is relatively heavy
- Pocket holes can be tricky if you don’t have a jig
- It’s not so easy to plug a pocket hole in MDF – this can spoil the appearance or be an exposed area for moisture to be absorbed which will swell and warp your MDF