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How to Cut MDF to Size Correctly
Author Chigwell Building & Joinery
Date 09/02/2022
Medium-density fibreboard (MDF) is a type of engineered wood which has gained a lot of popularity over the years.
It has some similarities to plywood, but it is considerably denser.
MDF is made by combining wood fibres with wax and resin binder using intense pressure and high temperatures.
Since it is quite dense it is important to be aware of the best tools and methods to use to cut MDF to size.
Let’s dive in and discover more about how to correctly cut MDF to size.
Table of Contents
- Safety First
- Straight Cuts in MDF
- Curved Cuts in MDF
- Cutting Holes in MDF
- Routing MDF
- Sanding & Finishing
- Conclusion
Safety First
Image source: Pixabay
It is important to take certain precautions to ensure your safety.
Bear in mind that since MDF is quite dense, you may experience some difficulty cutting it unless you use the right tools.
Moreover, as large quantities of dust are produced when cutting MDF, you need to wear proper attire.
This is especially true since it contains formaldehyde resins, which are quite hazardous.
- Wear thick, heavy-duty working gloves
- It is best to be wearing a long sleeved shirt to reduce the possibility of scratching yourself against the edges of the MDF or the saw blade. However, make sure the sleeves are not loose as you do not want to risk having them get caught in the saw blade while cutting.
- It is highly recommended that you wear a dust mask and safety goggles. While cutting MDF, there will be a lot of dust particles released into the air. These can easily get into your eyes and be inhaled unless you’re wearing a mask and goggles.
- It’s advisable to carry out the cutting process in a large and clear area. Doing this outside may be the best option if you do not have a garage. Otherwise, make sure to open any windows and doors so that there won’t be too much dust accumulating. Also cover anything close to the working area to protect them from the dust.
Straight Cuts in MDF
Image source: Pixabay
To make straight cuts you can use any one of the following tools and methods.
While electric tools or most hand held cutting tools such as the ones mentioned below will cut through MDF boards, the most important thing is that the blade used is carbide-tipped.
Since MDF has a very high glue content, a blunt blade will not cut clean edges.
Circular Saw
Using a circular saw is one of the most popular options to make straight cuts in MDF.
It’s best to use a circular saw which has a cutting speed of around 3,000 metres per second.
A blade which has at least 60 teeth, and which is around 14 inches wide is recommended.
If possible, the blade should have a carbide tip.
Position the circular saw so that the bottom of the saw blade is flush against the MDF board’s side.
Adjust the lever or saw’s depth knob and move the blade until the tip is sitting just below the MDF board.
For the blade to cut properly, it’s best to have the tip sitting between ⅛ and ¼ inches below the MDF board. Then, retighten the lever.
The MDF board is best placed on a large working table or a saw horse.
It is important that the part where you will be cutting is hanging over the edge of the surface area.
Afterwards, lock the MDF plank in place by using heavy-duty clamps.
Mark where you will be cutting the plank either with a pencil or by using some woodworking tape.
Double check the marked line using a tape measure, and make sure it is aligned by checking with an L-square or a level.
Line up the circular saw’s front to this line.
Then you can start cutting the MDF plank by pushing the saw through it.
Try to hold it steady, and make sure that the cutting speed is consistent.
Take it slowly, holding firm to avoid the saw vibrating or kicking whilst cutting.
Table Saw
A table saw is a good option to cut MDF to size.
This tool is relatively easy to use and can guarantee precise rip and cross cuts.
Having said that, a table saw is not as affordable and as easy to carry around as circular saws since it will be fixed on a motor underneath a table.
It is important to note that table saw blades come in varying sizes.
Most of them are 10 inches in diameter.
It is advisable to use a smaller blade relative to the maximum size that your table saw can handle.
A larger blade will not be easy to manage.
A 50-80 tooth per blade is recommended to cut MDF to size since it is a dense material.
The following are the main types of table saw blades that you can choose from to cut MDF:
- Crosscut blades - with around 80-90 teeth these blades are ideal for MDF as they can cut through it properly and precisely.
- Combination blades - this is a common option, with a 10 inch diameter and with around 50 teeth. This is an ideal blade for a beginner.
- Composite blades - also known as multi-purpose blades, these have 60 teeth. You can rip as well as crosscut MDF.
Hand Saw
If you do not want to buy a circular saw or a table saw, you may simply opt to use a hand saw.
This is the most basic of saws available.
You will need to be very careful if you use it to make straight cuts on an MDF board as it is a difficult technique to be precise.
Only experienced carpenters or contractors can cut accurately with a hand saw.
Even if you mark the line where you intend to cut, it is quite hard not to veer off course.
Make sure you have a quality saw as MDF is a dense material.
The teeth need to be very sharp and the saw should have a thin kerf.
Mark the cut line, making sure it is highly visible all along.
Before starting the cutting process, get a straight edge and clamp it to the board, next to the cut line.
Ensure the board is well secured.
Make sure the clamps do not get in the way while you’re cutting.
It is recommended to score the cut line with a shard-edged knife to create a shallow guide cut for the blade to follow.
This will also help the blade’s teeth to cut through more easily.
When cutting, it’s best to start with a high angle to let the saw blade’s teeth into the groove.
Then, slowly bring the cut angle downwards till you cut through the board’s width.
Move the blade in a backward and forward motion, while gently pushing and pulling the saw blade against the straight edge.
All along, you need to ensure that the saw blade is brushing against the straight edge.
This will improve your chances of cutting through the MDF straight.
Once you have cut halfway through the MDF board, make sure that the free end is well supported so that it does not end up breaking off.
Then continue to cut until you complete the whole cut.
Laser Cutting Machine
Since MDF is so dense and with a faultless composition, it’s ideal for a laser cutting machine.
Lasers will be able to cut precise edges as well as engrave the MDF.
The result will be pinpoint accurate and consistent.
Laser cutting machines are rather expensive however.
It’s also worth noting that since the laser burns at high temperatures, it will evaporate the resin causing the MDF to emit poisonous formaldehyde fumes.
Hence, it’s crucial to make sure that safety precautions are taken should you use an MDF laser cutting machine.
Curved Cuts in MDF
Image source: Pixabay
To make curved cuts you may either opt to use a jigsaw or a rotary tool.
The more teeth the blade has, the less the possibility of chipping the MDF plank around the edges being cut.
As a result, a steel-cutting blade is generally recommended.
Here are the most recommended cutting methods respectively:
Jigsaw
For best results a jigsaw with a bi-metal cutting blade is the most suitable.
Carefully place the blade inside the device’s blade clamp mechanism.
A narrow blade with a lot of teeth is the best type.
Make sure the device is unplugged while installing the blade.
Set the MDF plank you want to cut on the work table securely.
Position it so that the area where the cutting will be made is hanging over the edge.
Place large clamps around its edges to fasten it in place, as you do not want it to move while you are cutting.
In case you are cutting in the middle of an MDF plank, it is best to place each end on a saw horse or a sturdy table.
Using a pencil mark where you want to cut.
A drafting compass may come in handy since you will be making curved cuts.
You could also use stencils.
Position the front of the jigsaw’s shoe at the starting point of the mark.
It is important to see that the blade is lined up with the marked line.
Then, turn on the saw and start cutting, moving slowly and gently.
Rotary Tool
A rotary tool fitted with a multi-purpose cutting blade is ideal to cut notches or when plunge cuts are needed.
Cutting Holes in MDF
Image source: Pexels
Drill
A drill which is either fitted with a regular bit, or a spade bit, can make holes of up to 1 ½ inches in diameter in MDF boards.
Should you need larger holes, or for holes that are not circular, you can drill the corners of the hole’s outline with a drill bit and then cut around with a jigsaw.
Rotary Tool
A rotary tool with a multi-purpose cutting blade can also be used to cut holes in MDF.
It is important that you guide the tool carefully around the outline and move slowly along.
Routing MDF
Image source: Pixabay
Basically any blade which can rout wood can also rout MDF.
However, it is important to use carbide-tipped blades so that they will not dull quickly.
While routing MDF, a lot of dust will be produced.
A handheld multipurpose tool with a routing accessory can produce less dust as it is smaller and easier to handle.
While routing, always move the tool against the direction of the blade rotation, as otherwise it might spin out of control.
You need to avoid this as it could easily ruin that particular edge.
Handheld Multipurpose Tool
A multipurpose tool can also be used.
Many opt for this option as it is a tool that is more affordable and suitable for various kinds of woodworking projects.
Such a tool will combine various individual functions within a single unit.
The most important thing is that you’re sure the handheld multipurpose tool you’ll be using is equipped with the right kind of blade for dense MDF boards.
Router
A router can also be used.
This power tool is characterised by a flat base, with a rotating blade extending past it.
The spindle can either be driven by an electric or a pneumatic motor.
The router is a portable tool and it can work well for MDF cutting, both for straight as well as curved cuts.
Sanding & Finishing
Image source: Pexels
It is important that once the cutting is done, the edges of the MDF are sanded down.
A 220-grit sandpaper is generally recommended for MDF.
Always wear a face mask to protect yourself from the fine dust particles that are produced.
After sanding, wipe off the MDF with a soft cloth, and look for any marks or scratches.
Should there be any, make sure to fill them with some drywall compound.
Conclusion
MDF is a versatile material which is considerably dense.
Therefore you need to be careful how you cut it to achieve flush edges.
By following the tips mentioned above with regards to tools, blades and methods, you should achieve better cutting results and a risk-free cutting experience.
