How To Drill Into Acrylic

Acrylic has become the go-to material for everything from sleek display cases to backyard aquarium windows. Yet one seemingly simple task stops countless DIYers dead in their tracks: drilling clean holes without turning their project into a spider web of cracks. The good news? Mastering this skill requires just the right combination of proper tools, controlled speed, and patience—not brute force.

Why Acrylic Demands Special Treatment

The Material’s Hidden Personality

Acrylic (often sold under the brand name Plexiglass) behaves nothing like wood or metal. This thermoplastic is 17 times more impact-resistant than glass, yet paradoxically vulnerable during drilling. The material’s molecular structure creates internal stress points that, when met with excessive heat or pressure, fracture in jagged, irreversible patterns.

Think of it like pressing on thin ice—steady, distributed weight keeps you safe, while sudden force sends cracks racing across the surface.

Cast vs. Extruded: Not All Acrylic Is Equal

Cast acrylic handles drilling better than its extruded counterpart because of its denser molecular structure. Cast versions resist stress cracking and provide cleaner hole edges, making them the preferred choice for projects requiring multiple drill points.

Essential Tools and Materials

Drill Bits That Make the Difference

Standard twist drill bits—the ones gathering dust in your garage—spell disaster for acrylic. Their aggressive cutting angles generate excessive friction, melting the material instead of cutting through it cleanly.

The FTM 7pc Acrylic Point Drill Bit Set features gold-coated flutes that maximize lubrication, while the 60-degree tip angle facilitates smooth chip removal. For single-diameter projects, the Craftics Drill Bit with its 90-degree cutting angle delivers professional results on acrylic, Plexiglass, and Lucite.

Supporting Cast of Equipment

Beyond the drill bit itself, success hinges on these components:

• Variable-speed drill or drill press for RPM control
• Clamps or weights to prevent sheet movement
• Scrap wood backing board to support the exit point
• Masking tape or painter’s tape for surface protection
• Center punch for marking precise drill locations
• Water or cutting lubricant to manage heat buildup
• Safety goggles (acrylic chips fly with surprising velocity)

The Science of Speed: RPM Recommendations

Drilling acrylic isn’t a race. The sweet spot lies in low to medium speeds that cut without generating destructive heat.

Larger holes demand slower speeds—a principle often counterintuitive to woodworkers accustomed to aggressive drilling. The shavings themselves reveal whether you’ve found the right tempo: smooth, continuous curls signal success, while crumbly fragments indicate excessive speed, and melted, fused chips mean you’re moving too slowly.

Step-by-Step Drilling Process

Preparation: Setting the Stage for Success

Step 1: Leave protective film intact. That factory covering isn’t just packaging—it’s your first line of defense against scratches. Mark your drill point directly on the film using a fine-tip permanent marker.

Step 2: Apply masking tape over the drill site. This double layer of protection prevents the drill bit from skating across the slick surface and reduces chipping as the bit breaks through.

Step 3: Create a pilot dimple with a center punch. A gentle tap creates a shallow depression that guides the drill bit precisely where you want it, eliminating the frustrating drift that ruins measurements.

Step 4: Secure the workpiece firmly. Clamp the acrylic to a stable, flat surface with scrap wood placed directly underneath the drilling area. This backing board is non-negotiable—it prevents catastrophic blowout when the drill exits the opposite side.

Execution: The Drilling Dance

Step 5: Set your drill to low speed. Resist the temptation to crank up the RPM. Start at the conservative end of the recommended range for your hole size.

Step 6: Position the drill perpendicular to the surface. Even a slight angle introduces uneven pressure that can crack the material. Hold the drill steady with both hands if working with a handheld model.

Step 7: Apply gentle, consistent downward pressure. Let the drill bit do the work—forcing the tool through the material generates friction heat that weakens the acrylic’s structure. The bit should sink through gradually, almost leisurely.

Step 8: Employ the peck drilling technique for thicker sheets. Every 1/8″ to 1/4″ of penetration, withdraw the bit completely to clear chips and allow cooling. This rhythmic approach prevents heat accumulation.

Step 9: Reduce feed pressure near the breakthrough point. As you approach the opposite surface, ease off significantly. This final phase is where most catastrophic cracks occur—the remaining material becomes increasingly fragile as you near completion.

Step 10: Apply coolant during drilling. For holes larger than 1/2″ or when working with thick acrylic sheets, periodically drip water onto the drilling area. The liquid absorbs heat that would otherwise stress the plastic.

Finishing Touches

Step 11: Deburr the hole edges. Use a countersink bit or deburring tool to smooth both the entry and exit points. These rough edges aren’t just cosmetic flaws—they’re stress concentrators that can initiate cracks later.

Step 12: Remove protective layers carefully. Peel away the masking tape and manufacturer’s film, revealing your pristine hole.

Advanced Techniques for Precision

Using a Drill Press for Professional Results

A drill press transforms acrylic drilling from nerve-wracking to nearly foolproof. The machine’s inherent stability eliminates the wobble that plagues handheld operations, while the adjustable depth stop ensures consistent hole depth across multiple pieces.

Set the press to the recommended RPM, secure your workpiece in the vise with backing material in place, and let the machine’s mechanical advantage handle the downward feed.

The Masking Tape Double-Layer Method

Some fabricators swear by applying masking tape to both sides of the acrylic sheet at the drill site. This sandwich approach provides additional chip resistance and clearer visual marking.

Preventing Edge Cracks Through Strategic Spacing

Never drill closer than 15mm (approximately 5/8″) from any edge. The material near perimeters lacks the internal support structure found in the sheet’s center, making it exponentially more prone to stress fractures.

Common Mistakes That Guarantee Failure

The Heat Trap Many Overlook

Even when using correct speeds, continuous drilling generates cumulative heat. Acrylic has a relatively low melting point, and once the material begins to soften, it loses structural integrity. The solution? Pause every few seconds to allow heat dissipation, and don’t hesitate to stop completely if you feel warmth building.

The Dull Bit Disaster

A sharp drill bit cuts cleanly; a dull one tears and generates friction. Acrylic-specific bits should be used exclusively on plastic materials to prevent premature dulling. Once a bit loses its edge, no amount of careful technique will prevent chipping.

Special Considerations for Mirrored and Colored Acrylic

Mirrored acrylic requires drilling from the reflective front side to prevent delamination of the metallic backing layer. Drilling from the rear causes the mirror coating to separate, creating unsightly bubbles around the hole.

Colored or tinted acrylic follows the same drilling principles as clear varieties, though darker colors hide minor scratches better than transparent sheets.

Safety Protocols You Can’t Ignore

Acrylic chips behave like tiny projectiles when expelled at drill-bit speeds. Safety goggles aren’t optional—they’re mandatory. The material also produces fine plastic dust that, while not immediately dangerous, shouldn’t be inhaled repeatedly over time.

Maintain a clean work area free of clutter that could cause slips or tool drops. A dropped drill mid-operation will almost certainly crack the acrylic sheet.

When Things Go Wrong: Salvage Strategies

Despite perfect technique, occasional cracks still happen. Small hairline fractures sometimes respond to acrylic solvent cement applied carefully with a fine applicator. The solvent actually melts the plastic molecules together, creating a molecular bond stronger than the original material.

For larger cracks or shattered sections, the unfortunate reality is that acrylic damage is usually permanent. The material’s brittleness that makes it so crystal-clear also makes it unforgiving of structural failures.

Benefits of Mastering Acrylic Drilling

Once you’ve conquered the technique, acrylic opens up remarkable possibilities:

• Mounting precision displays without unsightly adhesives
• Creating custom aquarium components with professional edges
• Building architectural installations that leverage acrylic’s clarity
• Fabricating protective barriers with ventilation holes
• Designing intricate jewelry or art pieces with multiple connection points

The material’s optical clarity rivals glass while weighing less than half as much. Its 10-times-greater shatter resistance compared to glass makes it safer for public installations, and its inherent UV resistance means outdoor projects won’t yellow or degrade.

Alternative Materials Worth Considering

Polycarbonate (Lexan) offers a compelling alternative for projects prioritizing impact resistance over optical perfection. Polycarbonate is 250 times more impact-resistant than glass—dramatically outperforming acrylic’s already impressive 10x advantage.

The trade-off? Polycarbonate scratches more easily and has a slightly milkier appearance. However, it’s less rigid than acrylic, meaning it doesn’t crack when drilled and can even be cold-bent without heating. For applications where drill holes are numerous or the material will undergo stress, polycarbonate deserves serious consideration.

Key Takeaways

• Use acrylic-specific drill bits with 60-90 degree tip angles to minimize friction and prevent melting
• Drill at low to medium RPM (150-600 depending on hole size), never exceeding recommended speeds for your diameter
• Always support the exit point with scrap wood backing to prevent catastrophic blowout
• Apply gentle, consistent pressure and let the drill bit cut rather than forcing it through the material
• Maintain 15mm minimum distance from edges and use masking tape over drill sites for added protection

Frequently Asked Questions (FAQ)

What is the best drill bit for acrylic sheets?

Acrylic-specific drill bits with 60-90 degree tip angles provide the cleanest results. The FTM 7pc Acrylic Point Drill Bit Set features gold-coated flutes and hi-molybdenum tool steel construction that cuts smoothly through acrylic, Plexiglass, and polycarbonate without chipping. High-speed steel (HSS) bits also work well when properly sharpened, though standard twist drill bits designed for wood or metal will almost certainly cause cracks.

Can you drill acrylic with a regular drill bit?

While technically possible, regular twist drill bits create far more problems than they solve. Their aggressive cutting angles generate excessive friction and heat, often melting the acrylic rather than cutting through it cleanly. The result is rough, chipped holes with stress fractures radiating outward. Acrylic-specific bits cost only slightly more but deliver exponentially better results by featuring sharper tips and specialized geometries.

How do you prevent acrylic from cracking when drilling?

Five critical factors prevent cracks: supporting the material with backing wood, using low drill speeds (150-600 RPM based on hole diameter), applying gentle downward pressure, cooling the drill site with water for larger holes, and maintaining 15mm distance from sheet edges. The peck drilling technique—withdrawing the bit every 1/8″ to clear chips—also prevents heat buildup that weakens the material’s structure.

What speed should I drill acrylic at?

Speed varies inversely with hole diameter. Smaller holes (1/8″-3/8″) work best at 400-600 RPM, while medium holes (1/2″-5/8″) require 200-400 RPM, and large holes (3/4″+) demand just 150-200 RPM. The shavings provide feedback: smooth, continuous curls indicate correct speed, crumbly fragments mean you’re going too fast, and melted chips signal excessive slowness.

How thick of acrylic can you drill through?

With proper technique, acrylic of any common thickness can be drilled successfully. However, sheets thicker than 1/2″ benefit from the peck drilling approach (pausing every 1/4″ of depth) and periodic water cooling to prevent heat accumulation. A drill press becomes increasingly valuable for materials exceeding 3/4″ thickness, as maintaining perpendicular alignment becomes challenging with handheld drills.

Is there a difference between drilling acrylic and Plexiglass?

No difference exists—Plexiglass is simply a brand name for acrylic. Both terms refer to the same thermoplastic material (polymethylmethacrylate or PMMA), and they drill identically. The more meaningful distinction lies between cast and extruded acrylic, with cast versions handling drilling better due to their denser molecular structure.

Should you drill acrylic from one side or both?

Always drill completely through from one side only. Attempting to drill from both sides and meet in the middle introduces alignment challenges that almost guarantee visible imperfections. For mirrored acrylic specifically, always drill from the reflective front side to prevent delamination of the metallic backing. The key is reducing feed pressure dramatically as you approach breakthrough on the exit side.