Have you drilled through the plastic but ended up with cracks and splinters?
Working with plastic or acrylic can be unfamiliar and intimidating, especially if you are used to working with wood, brick, or metal. You need to understand the material’s brittle nature and the drilling technique. No need to worry, as I have written this article to teach you how to drill holes through plastic and which drill type to avoid cracks.
In general, you can drill holes in plastic by following the steps:
- Mark the spot
- Clamp the plastic
- Place the twist bit and adjust the drill to the slowest speed
- Start drilling and change to reverse motion after
- Smoothen the area
We’ll dive into more detail below.
8 Steps on How to Drill a Hole in Plastic
Drilling plastic may appear to be a simple task, but if you’re not careful, your plastic could have splinters and cracks.
Here are the steps to do it right.
Step 1: Prepare the Materials
Prepare the needed materials and tools for the drilling process, such as:
- Pencil
- Ruler
- Drill with varying speeds
- Right-sized twist bit
- Sandpaper
- Clamp
- Painter’s tape
- Lubricant
Step 2: Mark the Spot
With a ruler and pencil, mark the areas where you will drill. A plastic drill as a result of an error requires precise measurements and markings. There is no turning back now!
Step 3: Clamp the Plastic
Tightly clamp the plastic to a stable surface and support the portion of the plastic you’re drilling with a piece of plywood underneath or place the plastic on a bench designated for drilling. With that action, you’ll reduce the possibility of resistance interfering with the drill.
Step 4: Place the Twist Bit
Insert the twist bit in the drill and tighten it down. Also, this is the best time to double-check that you’re using the correct bit size. Then, change the drill to the forward position.
Step 5: Adjust to Slowest Drill Speed
Select the slowest drill speed. If you’re using a drill that doesn’t have an adjustment knob, ensure the bit lightly depresses the plastic and try to control the speed by drilling slowly through the workpiece.
Step 6: Start Drilling
You can then start drilling through the plastic. When drilling, observe if the plastic chips away and gums up. If that happens, stop drilling to allow the area to cool.
Step 7: Change to Reverse Motion
Change the drill’s motion or setting to reverse and remove the drill bit from the finished hole.
Step 8: Smoothen the Area
With sandpaper, smooth out the area around the hole. Avoid scuffing off the area as you look for cracks, scruff, or splinters. When using the plastic, any crack will degrade the quality of the cut.
Essential Tips
To prevent your plastic from cracking, consider the following tips:
- You can attach painter’s tape to the plastic area where you intend to drill to keep the rest of the plastic from cracking. Then, after drilling, take it out.
- Use a small bit to start, then use an appropriate drill bit size to expand the hole to your desired size.
- When drilling deeper holes, use a lubricant to remove unwanted debris and reduce heat. You can use lubricants like WD40, canola, vegetable oil, and dishwashing soap.
- To prevent the drill from overheating, pause or slow down.
- When working with power tools, always wear your protective gear. Always maintain a safe working environment.
- Use a slower drill speed when drilling plastic because high drill speeds cause excessive friction melting through the plastic. Also, a slower pace will allow the chips to exit the hole more quickly. So, the larger the hole plastic, the slower the drill speed.
- Because plastics expand and contract with temperature changes, drill a 1-2 mm larger hole than required to allow for screw movement, contraction, and thermal expansion without stressing the material.
Appropriate Drill Bits for Plastics
While you can use any power drill for plastic drilling, using the correct drill bit size and type are critical to avoid chipping or cracking the material. I recommend using the following drill bits.
Dowel Drill Bit
A dowel drill bit has a center point with two elevated spurs that aid in bit alignment. The bit’s point and angle in front ensure smooth cutting and reduce stress in the front. Because it leaves a clean-sided hole, it is an excellent drill bit for plastic. It doesn’t leave any rough edges that could lead to cracks.
Twist HSS Drill Bit
A standard twist HSS (High-Speed Steel) drill bit is made of carbon steel that has been chromium and vanadium strengthened. I recommend drilling plastic with a twist drill that has been used at least once as it prevents burrs from forming and the drill from biting into the plastic. (1)
Step Drill
A step drill is a cone-shaped drill with progressively larger diameters. They are typically made of steel, cobalt, or carbide-tipped steel. Because they can create smooth-walled and straight hole sidewalls, step bits are ideal for drilling holes in plastic or acrylic. The resulting hole is clean and burr-free. (2)
Take a look at some of our related articles below.
References
(1) High-Speed Steel – https://www.sciencedirect.com/topics/
engineering/high-speed-steel
(2) acrylic – https://www.britannica.com/science/acrylic
Video Reference
