Q & A

9 Essential Tips For Screwing Into MDF

Most individuals seem to get nervous when they have to screw into MDF because of its sharp edges. For the past two decades, I’ve worked as a cabinetmaker, and putting MDF together is a regular part of my job.
The apprentices would constantly inquire about the best method for screwing into MDF edges without cracking the material.

Using a pilot hole and carefully pushing the screw in will prevent the MDF from fracturing. MDF can be fastened with regular wood screws with a straight shank.

MDF, or medium density fiberboard, is a handy material to keep on hand in the garage or basement workshop. It’s perfect for producing boxes, jigs, and templates because of its flat and smooth sheet form.

Despite its usefulness, many individuals have trouble putting it together because of its propensity to split and the screws’ poor grip.

Based on my extensive experience working with MDF, I have compiled the following nine suggestions for properly screwing the material together to ensure that the joints remain solid at all times and do not fracture.

Choose MDF of high quality and density.
Make sure the pilot hole is deeper than the length of the screw and always use the appropriate size bit before you start drilling.
Use a clearance hole and a countersink bit at all times.
Attaching screws to MDF, keep them 3′′ (75mm) from the edges.
Be careful not to overtighten the screws.
Be sure to align your drill with the centre of the MDF edge before beginning.
Use screws with straight shanks.
Tips for driving screws into MDF board edges
If you want to learn more about each of these, keep reading!

Why Does MDF Split When You Screw It?

The screw serves as a wedge, forcing the fibres inside the MDF to separate, and thus causing the splitting. When a pilot hole is not used, the material splits.

Inquiring minds should read my piece on the subject of how durable MDF is. Its capabilities may be overestimated.

Manufactured wood product (MDF) is manufactured by adhering wood fibres together with a synthetic resin. Combine all of the ingredients and press them together in a massive press.

Those of you who are wondering whether or not you can use pocket holes in MDF should read the article I just wrote.

Due to the nature of its production, the reason MDF cracks is now readily apparent. This article will explain why and how you should take special care when screwing it together.

Have you heard?

A typical thickness range for MDF during production is between 230 and 610 millimetres.

Can You Screw Into The Edges Of MDF?

If a suitable pilot hole is drilled and the screw is not tapered, it is possible to screw into the edges of MDF without cracking the material.

Most novices have difficulty with the edges of MDF. The screw can function as a wedge, hence a pilot hole is required if edge-screwing MDF. See here for advice on how to measure for a suitable pilot hole.

In contrast, screwing into an MDF face is not nearly as damaging. Screws can be driven directly into its face without fear of splitting. To be honest, there are times when I resort to a pilot hole for this.

I was wondering if anyone has a good use for MDF offcuts. Whether or not MDF can be burned is a key question. That’s why I decided to write this article and let the world know the truth.

I recently polled members of a sizable Facebook community to find out their MDF-related concerns.

Survey of MDF
The vast majority of people are worried that their screws may split the MDF. This article’s intent is to offer some comfort at such times of worry.

Here Are The 9 Essential Tips To Successfully Working With MDF

One, make sure the MDF you’re using has a high enough density.
Density of Medium-Density Fiberboard
You can find MDF just about anywhere, and its density ranges from manufacturer to manufacturer. The usual density of MDF is between 0.022 and 0.029 lb/in3 (600–800 kg/m3).

Low-density MDF can be purchased in some stores. That means far less compaction occurred during production. Inevitably, low-cost MDFs with a low density will be more difficult to work with than their more expensive counterparts.

Because of this, you should always go with a better MDF grade, or “standard” at the very least. When it comes time to put it together, you’ll appreciate the increased density.

Stronger and more likely to keep your screw in place over time is MDF with a higher density. Low-cost, low-density MDF won’t keep screws in place if there’s any movement.

Always use one of my trusted shop vacs when dealing with MDF.

The various qualities of MDF and how to identify them are illustrated below.

Cost-effective workshop preparation techniques
The second rule of pre-drilling is to always use the appropriate sized pilot hole.
The use of pre-drilled screw holes is mandatory when working with MDF. Typically, this is the root cause of MDF splitting when working with a novice. The single most important thing you can do to ensure success is to drill a pilot hole first that is sized appropriately for your screw.

Methods for determining the appropriate pilot hole size are outlined below:

Pick the screws you want to use.
Choose a drill bit with the same diameter as the screw’s shank.
Put the screw and the drill bit up to the light to make sure they are the appropriate size.
Make sure the hole is not too huge or the screws won’t be able to hold onto the MDF.
You should probably test it out on a spare piece first.
The procedure is demonstrated in the video below.

Size of Pilot Hole?
Be sure to read my post on finding the ideal pilot hole size every time if you’d rather refer to a chart than rely on your own judgement.

By drilling a pilot hole first, you can prevent the MDF from splitting as the screws bite and grip the material instead of wedging the fibres apart.

Third, make sure the pilot hole is deeper than the screw’s whole length.
A pilot hole is only effective if it is drilled to the exact depth that the screw will penetrate the MDF.

Drilling pilot holes that are too short compared to the screw’s length is fairly typical. The leftover screw can cause the MDF to crack, therefore this is not a good solution.

As a rule of thumb, I think it’s best to drill your pilot hole just a hair longer than the length of the screw. That way, even if you unintentionally drive the screw in too far, there won’t be any cracking.

If your screw extends into the MDF by 2 inches (50 mm), then your pilot hole should be drilled to a depth of 60 mm.

It’s not as crucial as drilling a pilot hole, but using a countersink bit every time can help you achieve a better result.

To make room for the screw head, a countersink bit simply creates a depression. This prevents the head from ripping the MDF fibres apart as the screw is tightened.

This is especially vital when screwing into MDF at its edge. To complete the polished aspect of your product, use a countersink bit to drill a tidy hole into which to insert the screw heads.

Drilling holes in MDF panelling. Would you say they are effective? For your convenience, I’ve written some words here.

Clearance holes are strongly suggested for use in recommendation number 5.
As I mentioned before, a clearance hole is different from a pilot hole. For the screw shank to pass through the primary surface with ease, a clearance hole must be drilled in the surface.

Simply put, what is a clearance hole?

In my post, I explain in detail what clearance holes are and why you need them.

Also, a clearance hole will give relief for the screw when it is tightened, preventing the MDF from cracking as a result of over-tightening. In most cases, you’ll be screwing MDF boards together along their edges rather than through their faces.

When working with MDF, it is imperative that high-quality dust collectors be used at all times. I have published a post that compares various dust collectors specifically for MDF. You should have a look.

After the screws have been tightened, there is some wiggle room provided by the clearance holes. All it takes is a light tap with a hammer to align all of your joints.

You wouldn’t have that much wiggle room to fine-tune your joints if you had simply utilised a pilot via the main component.
Space Screws 3″ (75mm) From MDF Ends
How to Screw Up MDF
As the extremities of a piece of MDF are not supported, the fibres there tend to be weaker. Always drive screws into MDF at least three inches (75 millimetres) from the board’s edges. There will be much less of a possibility of it cracking if you do this.

No matter where your screws are going into the MDF, it is still strongly advised that you utilise a pilot drill.

In MDF, preparation is simple. Here is my comprehensive tutorial on planing MDF.

Follow this guideline when putting together any wood. Preventing wood from breaking and improving the final product’s aesthetics are also benefits of inserting screws from the ends.

For some reason, inexperienced hands have a habit of trying to position screws close to the ends of a piece of wood. Doing so is both unnecessary and unprofessional. You can try putting the screws in and see how much better it works.

7: Don’t Overtighten the Screws

MDF is not as sturdy around the edges as solid wood because it is manufactured from pressed wood fibres. Therefore, you should tighten your screws securely without trying to strip them.

If you overtighten the screw, the threads will pull through the MDF, and you’ll have to start over with a new hole. If you have a screw that has become stripped, this is the place to come.

Some Suggestions for Creating the Ideal Tension
Using the clutch on your cordless drill is a quick and easy way to ensure that screws are tightened to the proper degree. The collar at the very top of the drill that can be rotated and has markings on it is the clutch. Overtightening your screws is something the clutch is designed to protect you from.

When you try to drive a screw in with a drill while the collar is set to the lower numbers, you’ll hear the drill slip. It will allow you to drive the screw deeper before it slips if you set it to a higher number.

Test out different clutch settings until you find one that works well for you.

Drill into the middle of the MDF edge at all times, rule 8.
There will be much less of a danger of fracturing the MDF if the screw is driven into the centre of the edge. There may not be enough wood fibres on the outside edge to sustain the screw if it wanders off or if you drilled in the wrong spot.

It will cause the MDF to crack, and it may even cause a breakout on the exterior. Both of these scenarios will lead to a very weak joint in addition to looking terrible.

Always measure the MDF’s thickness and divide by 2 to ensure you’re drilling straight through it. Make a pencil mark at that size to guarantee smooth, even seams.

MDF, for instance, typically has a thickness of 5/8 inches (16mm). So that the screw is always precisely in the middle, I’d measure and mark an area 5/16″ (8mm) in from the edge with a pencil.

WT Conceive & Construct / @WOODTECHIOM
Dowels are always splitting the MDF because they are inserted too tightly and too close to the board’s end. I only needed one cutter, so I skipped the first dowel.
6:10 PM · Dec 3, 2018 1 \s0 \s9. The use of a wood screw with a straight shank is recommended.
Whenever possible, when working with MDF, use a wood screw with a straight shank rather than a tapered one. The wood fibres will be forced apart when the tapered wood screw is driven in, serving as a wedge.

Nowadays, tapered wood screws are primarily only a relic of the past and are rarely utilised in any kind of woodworking.

It’s best practise to drill a pilot hole before using any kind of screw.

Is a jigsaw suitable for cutting MDF? I’ll let you know whether this is even achievable.

What Screws Should You Use For MDF?

The best type of screw for medium-density fiberboard (MDF) is a medium- to coarse-threaded straight-shanked screw that is at least twice as long as the thickness of the board being screwed.

To screw through a piece of MDF that is 5/8′′ (16mm) thick, for instance, a screw that is at least 40-50mm long is recommended. The reason behind this is that MDF requires an abundance of threads to provide a good grip on the fibres.

Threads that are coarser are better for MDF because they penetrate deeper into the fibres and hold more securely. Finely threaded screws would become unfastened as soon as any pressure was applied during the tightening process.

The MDF industry has seen the introduction of “special” screws purportedly designed for use with MDF by a few manufacturers. Spending money on these is a waste of time because they behave like any other screw would. Regular wood or chipboard screws are what I recommend using unless you have a lot of MDF work to do.

Do Wood Screws Work On MDF?

MDF can be fastened with wood screws as long as they are not tapered and a pilot hole is drilled first.

When fastening MDF boards together with screws, a pilot hole is required in every instance. This makes for a solid connection that is less prone to cracking. The coarser thread often seen on wood screws is an added bonus.

Since they are straight shanked and feature a coarse thread, chipboard screws are another excellent option for MDF.

Wood screws can be used in MDF, but you should still follow the 9 guidelines outlined above.

Can I Use Drywall Screws In MDF?

Drywall screws are too fine and won’t grasp or bite into the MDF fibres, so they shouldn’t be used for screwing into the margins of MDF.

Face screwing with drywall screws would work, but I’d rather use an 8-gauge wood screw. Similarly, drywall screws tend to be fragile and break easily under pressure.

Use a regular wood screw that fits the above description for the greatest results. Normal wood screws will do the trick if you follow the above steps, however you can save some money by using MDF-specific screws.

America’s SPAX @SPAX USA
There’s no need to do any pre-drilling or split the wood. Designed to work with hardwoods and medium-density fiberboard.
6:02 PM · Aug 24, 2015 1 \s2

Does MDF Hold Screws Well?

As long as the density of the MDF is high and the screw is long enough to engage three-quarters of its thread count inside the MDF, the screw will stay there. If you drill a pilot hole first and don’t overtighten the screw, it should stay put.

Provided the aforementioned procedures are adhered to, I have never witnessed a screw pull out of MDF in my 30 years of expertise in a cabinetmaking shop, unless some unexpected excessive force was given to the parts.

It’s true that MDF isn’t popular and that it does necessitate the use of safety gear when being machined, but it does have some applications. Since it is so flat and solid, it works great for making jigs and simple boxes. As long as it is kept away from any body of water, that is!

While MDF lacks the aesthetic appeal of genuine wood, the techniques outlined here will allow you to successfully screw into it in your workshop.


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