Special considerations for drilling into trim plastic?

Question

I'm trying to install some cargo nets in the trunk of my 2018 Subaru Crosstrek. Although that the nets are not listed as compatible with the 2018 and later, I have found many reports of people successfully installing them in 2018 and later Crosstreks, and I have found the drill points marked in my car.
The instructions (PDF) state that I'll need to drill one 1/2" hole on each side for the 4th anchor for the net, with the other 3 preinstalled. Before the 1/2" hole, the instructions state to drill a 1/4" pilot hole. There's no special requirements listed for the bits other than size. Though I have a fair amount of experience drilling wood and metal, I haven't done much with plastic. I was about to go ahead and use standard twist bits to drill, but my significant other has had bad experience with drilling plastic and is concerned that I'll botch the job and crack the trim piece.
Looking online, I've found varying advice for drilling plastic, and nothing specific to automotive interiors. I've found advice to use pointed bits labelled for plastic use, spade bits, dowel bits, and stepped bits.
I'm a member of a tool library, so I can get most kinds of bits from there. Is a standard twist bit OK, or should I go with something specialized? Any special considerations for drilling technique?

fred_dot_u · Accepted Answer

Most internal plastic in motor vehicles is ABS, which is relatively "soft" when it comes to drilling. A conventionally ground bit can and will grab during the drilling, but it's unlikely to crack the plastic. Harder plastic such as acrylic should be drilled with special bits or special techniques such as reversing the drill motor, but ABS is pretty straightforward. Jumping from a quarter inch bit to a half inch bit may not be the best route, though, as it will likely grab and tear. Make sixteenth-inch jumps from the initial quarter inch bit to ensure better results.
I drill ABS often enough to have no problems, but I use the small step method. One day, I should try the drill motor reverse method. It's probably not all that good in ABS anyway, as the heat will soften the plastic before it cuts through, making a bigger mess of the hole.

Special considerations for drilling into trim plastic?

One Answer

Add your own answers!

Ask a Question