Plastic is easier than most materials—you don’t need specialist bits. But the main enemy is melting, not breaking. Get the speed wrong and you’ll melt a gooey ring around the hole. Get the technique right and it’s quick work.
Drill Bits for Plastic: What Works
Standard HSS Bits
Ordinary High Speed Steel twist bits work fine on plastic. Any bit from a general-purpose set will do the job. The key is speed—too fast and the friction melts the plastic; too slow and you’re wasting time.
Best for: General plastic sheet, acrylic, polycarbonate, ABS. Sizes 2mm to 13mm typically used.
Speed: 1500 to 2500 RPM for most plastics. Acrylic and polycarbonate can handle up to 3000 RPM if the bit is sharp. PVC should be slower (around 1000–1500 RPM).
Advantage: You’ve probably already got these bits.
Brad Point Bits
Brad point bits are excellent on plastic because they’re sharp and precise. They prevent the bit from wandering and cause less melting because the edges cut cleanly rather than rubbing and generating heat.
Best for: Precision holes on acrylic or polycarbonate sheets, where edge quality matters. Sizes 3mm to 12mm.
Speed: 1200 to 2000 RPM. Brad point bits work well on plastic at moderate speeds.
Advantage: Cleaner holes with less melting around the edge.
Amazon: Brad Point Drill Bits on Amazon UK
Plastic-Specific Bits
Some manufacturers make bits designed specifically for plastic. They have a wider cutting angle (60–90° instead of the standard 118°) and sharper edges. These bits are excellent and reduce melting significantly, but they’re not essential—sharp HSS bits do the same job.
Best for: Drilling a lot of plastic holes, production work. Sizes 2–12mm.
Speed: 1200 to 2500 RPM.
Cost: Slightly more than standard bits.
What NOT to Use
Masonry bits: The wide cutting angle and aggressive design will grab and crack thin plastic.
Dull bits: This is the main enemy. Dull bits slide and create friction rather than cutting. This generates heat and melts the plastic.
Spade bits: Too aggressive and unpredictable on thin plastic.
Drilling Different Types of Plastic
Acrylic (Perspex)
Popular for signs, light covers, and craft projects. Brittle compared to some plastics—cracks easily if you’re not careful. Drilling is straightforward if you’re gentle.
Speed: 1500–2500 RPM. Start at the lower end.
Pressure: Very light. Let the bit do the work. Heavy pressure can crack the acrylic.
Backing board: Essential. Clamp a wooden backing board underneath to prevent cracking on the exit side.
Melting: Acrylic doesn’t melt as much as PVC, but heat can still damage edges. Keep speed moderate and don’t linger.
Polycarbonate
More flexible and tougher than acrylic. Used for protective sheets, skylights, and safety equipment. Easier to drill than acrylic.
Speed: 1500–3000 RPM. Polycarbonate tolerates faster speeds.
Pressure: Moderate. Polycarbonate is forgiving—it won’t crack as easily as acrylic.
Backing board: Still recommended to prevent chipping on exit.
PVC Plastic Sheet
Rigid PVC sheet is common for building, electrical conduit covers, and industrial applications. PVC is tough but the main issue is melting—PVC softens at lower temperatures than acrylic.
Speed: 1000–1500 RPM for thick sheet. Too fast and you’ll melt the edges brown.
Pressure: Light to moderate. PVC chips easily if you push too hard.
Backing board: Yes, to prevent chipping.
Tip: PVC melts faster than other plastics. If you see the edges turning brown or soft, slow down or stop and let it cool.
PVC Pipe (Rigid and Flexible)
Drilling PVC pipe is common for irrigation, plumbing, and DIY projects. The technique is slightly different because the pipe is hollow and round.
Speed: 1000–1500 RPM. PVC pipe melts easily.
Support: This is critical. The pipe must be fully supported along its length, not just held by hand. Clamp it in a vice or to your bench. If the pipe flexes or moves during drilling, it cracks.
Backing board: No backing board needed if you’re drilling through the side of the pipe. If drilling into an open end, support the inside with a scrap block.
Pressure: Light. Let the bit do the work.
Deburring: After drilling, smooth the inside and outside edges of the hole with sandpaper or a deburring tool. Rough edges can weaken the joint if you’re gluing fittings.
ABS (Acrylonitrile Butadiene Styrene)
Tougher and more heat-resistant than acrylic. Used for automotive trim, plumbing fittings, and thick plastic enclosures. Drills easily.
Speed: 1500–2500 RPM.
Pressure: Moderate. ABS is forgiving and won’t crack under normal pressure.
Backing board: Recommended.
Step-by-Step Drilling Plastic
1. Clamp the Plastic
Never hold plastic by hand. Clamp it to your bench or workbench with protective padding (cloth or rubber sheet) between the clamp and plastic to prevent pressure marks. The plastic must not move during drilling.
For PVC pipe, use a vice or V-block and secure it along its full length, not just at one end.
2. Use a Backing Board (for sheet plastic)
Clamp a wooden backing board underneath the sheet, about 5–10mm away from the surface. When the bit breaks through, it exits into the wood and prevents cracking and chipping on the underside.
3. Mark the Hole
Mark the centre of the hole with a felt-tip pen. You can also use masking tape to mark the spot and prevent the bit from slipping at the start (the tape helps anchor the bit).
4. Set the Right Speed
Speed varies by plastic type (see table below), but the rule is: start slower than you think necessary. Too fast causes melting. Too slow is just slow. If the plastic edges start to look brown or soft, stop immediately and let it cool.
5. Drill with Light Pressure
Apply steady, gentle pressure. The bit should be doing the cutting, not the pressure. If you need to push hard to make progress, the bit is dull—stop and sharpen or replace it.
Don’t apply sudden pressure changes or jab the bit—keep it smooth and steady.
6. Back Out Frequently
Every 10–15 seconds, back the bit out of the hole to clear plastic chips and shavings. These chips can jam around the flutes and generate heat. Clearing them prevents melting and keeps the hole clean.
7. No Hammer Action
Percussion mode will crack plastic. Use a smooth drilling motion only. Switch off hammer action if your drill has it.
8. Cool Down if Needed
If the plastic around the hole starts to feel hot or look soft/brown, stop. Back the bit out and let it cool. You can splash a little water on the hole to speed cooling (especially with PVC). Wait 30 seconds, then continue at slightly slower speed.
9. Deburr the Edge
After drilling, the hole has plastic burrs on both sides. Smooth them with 120-grit sandpaper or a deburring tool. This takes 30 seconds and makes the hole look finished and professional.
Speed and Pressure Quick Reference
| Plastic Type | Speed (RPM) | Pressure | Main Risk | Best Bit |
|---|---|---|---|---|
| Acrylic (Perspex) | 1500–2500 | Very light | Cracking on exit side | Brad point or HSS sharp |
| Polycarbonate | 1500–3000 | Moderate | Chipping edges | HSS or plastic bit |
| PVC Sheet | 1000–1500 | Light | Melting edges brown | Brad point or HSS sharp |
| PVC Pipe | 1000–1500 | Light | Melting and cracking | HSS or plastic bit |
| ABS | 1500–2500 | Moderate | Bit walking/jumping | Brad point or HSS |
Common Problems and Solutions
Melting / Brown Edges
Cause: Too fast speed or dull bit.
Fix: Slow down the drill speed by 30–50%. If that doesn’t help, the bit is dull—replace it. Back out every 10 seconds to clear chips and reduce heat.
Cracking (Especially Acrylic)
Cause: Too much pressure or vibration. No backing board on exit side.
Fix: Always use a backing board underneath. Apply very light pressure and let the bit cut. Clamp the plastic firmly so it can’t flex.
Bit Wanders or Walks
Cause: Dull bit or no pilot hole for large holes.
Fix: Use a sharp bit. Mark the hole clearly and start slowly at 45° angle, then straighten. For large holes (over 8mm), drill a small pilot hole first.
Plastic Chipping Around Hole
Cause: Speed too fast or pressure too high. Dull bit.
Fix: Slow down. Reduce pressure. Replace dull bits. Use a backing board and masking tape to minimise chipping.
Bit Sticks or Binds in Hole
Cause: Plastic chips jamming around the flutes. Heat melting plastic around the bit.
Fix: Back out every 10 seconds to clear chips. Slow down speed if plastic is melting. Never force the bit—let it rotate freely.
Tools You’ll Need
- Variable-speed drill: You need to dial speed down to 1000–2500 RPM depending on plastic type.
- Sharp HSS or brad point bits: Dull bits cause most problems.
- Clamps and protective padding: To hold plastic firmly without marking it.
- Backing board (for sheet plastic): Scrap timber clamped underneath.
- Masking tape: Optional but helps prevent bit slip and reduces chipping.
- Sandpaper (120 grit): To deburr edges after drilling.
- Vice (for PVC pipe): To hold pipe securely during drilling.
When NOT to Drill Plastic
Some plastics are fragile or unsafe to drill:
- Very thin plastic film: Will melt or shatter. Not worth attempting.
- Rigid foam: Will compress and crumble around the hole. Use a drill press with sharp bit if necessary.
- Polystyrene (expanded foam): Will melt. Not recommended.
- Toughened polycarbonate: Check the label—some variants are hardened and difficult to drill cleanly.
Amazon: HSS Drill Bit Sets on Amazon UK
Amazon: Plastic Drill Bits on Amazon UK
See also: What Drill Bit for Wood
See also: What Drill Bit for Masonry
See also: Drill Bit Size Chart
Watch: Video Guide
Frequently Asked Questions
Why does my plastic melt when I drill it?
Heat from the drill bit is melting the plastic. This happens when speed is too fast or the bit is dull. Friction generates heat, and plastic has a low melting point. Slow down your drill speed and make sure the bit is sharp. Back out every 10 seconds to clear chips and reduce heat buildup.
What’s the best speed for drilling plastic?
It depends on the plastic type. PVC and acrylic: 1000–1500 RPM. Polycarbonate and ABS: 1500–2500 RPM. Start at the lower end and increase if needed. If you see brown edges or softness, you’re going too fast—slow down.
Can I use a metal drill bit on plastic?
Yes. Standard HSS bits (metal-cutting bits) work fine on plastic if they’re sharp. They’re not as clean as brad point bits, but they’ll do the job. Make sure they’re sharp—dull metal bits cause melting on plastic.
Do I need a backing board for plastic?
For sheet plastic, yes. It prevents cracking and chipping on the exit side when the bit breaks through. For PVC pipe or thick blocks, it’s less critical, but still recommended. It only takes a few seconds to clamp a backing board and it makes a huge difference to hole quality.
Why does acrylic crack when I drill it?
Acrylic is brittle and cracks under pressure or vibration. Use very light pressure and ensure the plastic is firmly clamped so it can’t flex. Always use a backing board underneath. For large holes, drill a small pilot hole first. Brad point bits are less likely to cause cracking than twist bits.
Can I drill PVC pipe?
Yes, absolutely. PVC pipe drills well if you support it properly. Clamp the pipe firmly in a vice or to your bench along its full length—don’t just hold it by hand. Use slow speed (1000–1500 RPM) and light pressure. Deburr the inside edge after drilling if you’re gluing fittings.
