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Drilling plexiglass can be challenging because it can be prone to cracking or melting when it is drilled. There are some important steps that must be followed to make sure that your drilling process goes smoothly and creates a good end result. Traditional drill bits and traditional drilling processes can cause damage to the plexiglass.
What is Plexiglass?
Plexiglass is a glass alternative that is perfect for rooms or uses that would cause normal glass to break. It is made of acrylic and it has been around since the 1920’s.
While nearly as translucent as glass, it is much more durable, making it a great product for use in applications where there could be damage to a glass pane.
Plexiglass is used in airplanes, lighthouses, gyms, greenhouses, and all kinds of other places. You might not be aware of the many locations that you have visited that has used plexiglass for windows and covers to block sensitive screens or other items that need protection from moisture and other damage.
Because plexiglass can be brittle and shatter, you must always wear a mask and safety glasses when you are drilling into it. Dust and other debris from plexiglass can be quite sharp and could injure your eyes or your lungs.
You should never assume that you will not be exposed to dust and acrylic chips just because you are working outside for example.
It is a good rule of thumb to always have safety glasses on when you are drilling into any surface, but plexiglass is one of the materials that you cannot afford to be casual about working with.
Acrylic products are well-known for their durability, but they are also well known for causing a health and safety risk if they are broken or melted.
What Kind of Drill Bit to Use
You might be wondering if you need a specialty drill bit for your plexiglass drilling project. You’ll want to have a base set of drill bits that you should invest in before you start drilling into plexiglass, but all of them can be used with your regular hand drill. You will not need another specialty drill for this project.
- Plastic Drill Bits: These are specifically made for plastic product drilling. They will not get as hot while you work and they actually shave and scrape out the hole rather than just drilling it straight through. They come in many diameters and they will have different kinds of ground flukes with 90-degree points and a 0-degree rake. This is a great solution if you want to avoid melting your plexiglass while you drill it.
- Modified Drill Bits: These drill bits are traditional drill bits that have been specifically designed or modified to work well on plexiglass. The bits might come this way, or you might choose to modify them yourself before use. To modify a traditional bit, you will grind the small flats on the cutting edges down. This modification will cause less grab as the drill bit is used, making it less likely to break or melt the plexiglass.
- Diamond Dusted Drill Bits: These bits are made to drill through hard or thick plastics. The drill bit has diamond dust coated on the exterior of its cutting surfaces, making it stay sharp and making it less likely to break or crack the plexiglass as you work. They will typically have 60-degree points and 0-degree rake. These are the perfect drill bit if you are going to drill through many layers of plexiglass or one thick sheet. They can run hotter than a regular bit, so slow drill speeds are suggested to prevent melting.
1. Prepare to Drill
Pick out the right size drill bit, or you might use a drill press as well. If you don’t have this tool, there are plenty of cheap drill press options available. They are a huge help if you have a lot of drilling to do.
Put your sheet of plexiglass on a flat surface. It can bend slightly if you try to hold it and drill, and the added flex of the material can lead to cracks or can even break the plexiglass.
You might not be able to see that the sheet is bending, but the internal structure of the sheet of plexiglass can be affected.
If you are going to use a drill press, you will work at a speed of about 500 to 1,000 RPM. You can also get acrylic-specific drill bits for your drill press. This is probably the best course of action to be sure that you will not damage or melt the plexiglass as you use the drill press.
Use another sheet of ruined plexiglass or a medium density fiberboard under your plexiglass that needs to be drilled.
You can use clamps to attach the two sheets to one another. This protects the backside of the sheet of plexiglass from showing damage or roughness when you are done drilling.
Learn how to cut through acrylic with our guide.
Take a scrap from your plexiglass and practice drilling a few holes. There is a certain amount of pressure and speed that is ideal for this project and practicing can help prevent damage to your larger sheets of plexiglass that you need for your project to be completed.
You will also be able to tell if you have selected the right drill bit if you practice. There is no way to fix a broken sheet of plexiglass, so taking the time to verify that you have the right drill bit and the right technique is a good habit to get into each time you change drill bits.
Don’t use dull drill bits – make sure to sharpen your bits or pick up some new ones.
3. Start Drilling Slowly
Be aware that if you need to drill at the edge of the sheet of plexiglass, it will be more likely to break or crack. You should work very slowly if you are placing holes near the edge of the sheet.
No matter where the hole is located, you will need to start very slowly and create a dimple or divot to mark the spot where your hole will be. Or, you could opt to drill a pilot hole.
It is a good idea to make your divot with a smaller drill bit. You will just need this divot to guide the very tip of drill bit when you are just starting to create the hole.
Drill slowly and carefully as you begin. Making sure to use even pressure.
4. Keep a Smooth and Steady Pace
You will need to be smooth and steady as you drill this kind of hole. Plexiglass can catch or grab the drill bit, so you cannot run the drill bit in and out quickly like you would with a wooden surface, or you will break the plexiglass.
Slow and steady is the name of the game and you should plan to press down in one smooth motion to the depth that is required.
Because plexiglass is transparent, you should be able to see clearly if you are through the full thickness of the material and you will be able to ensure that there are no cracks or other damage to the area around the hole.
You can then run the drill in and out of the hole a couple more times if needed to smooth out the rough edges and deburr the hole.
Always make sure that you check the temperature of the drill bit when you have drilled the first pass through the hole. If it is hot at this point, let it rest and cool down.
If you have a dremel, you can cut your acrylic. Read our guide to learn how.
5. If Your Sheet of Plexiglass is Thick
If you are trying to drill through a thick sheet of plexiglass and you feel like the drill is just grabbing the material and not going through smoothly, you can switch to a smaller and sharper drill bit and make a series of small holes around the center mark that you have made.
This is called peck drilling, and it can be a great way to get a hole started when you are dealing with thick materials.
Make sure to let the drill rest and cool off in between each hole that you drill so that you do not melt the plexiglass.
You will be able to blend the small circles of hole when you are done by drilling a central hole with this smaller drill bit. You can then use a larger drill bit to deburr and clean up the edges of your peck-drilled hole.
This is a great trick to prevent damage to the plexiglass that would potentially shatter or crack it, and it is much easier on your tools and equipment as you work.
This is also a great way to make sure that there are no hidden imperfections or cracks in the plexiglass near the hole that could lead to the sheet failing or cracking across when you try to install it.
Drilling plexiglass does not have to be challenging if you plan ahead and take your time. Buying the correct drill bit and making sure that you attach the plexiglass to another sheet of material to protect the exit side of the drilled holes are essential steps in the process to create a good final outcome.
Always remember to wear your protective glasses and a mask and to practice on some scraps of Plexiglas before jumping in to drilling your larger sheets of material.