Jeff
Well-known member
I will be adding mini-LEd's to the plastic grill of my truck. They require a 3/4" hole. I need some tips on how to successfully drill in plastic without cracking or melting.
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Drilling in Plastic Questions
- Thread starter Jeff
- Start date
I've never personally had an issue with drilling interior plastics in cars. I've installed switches, power ports, etc. I just drill a pilot hole and size up. My drill bits always cut through like butter with no cracking. If you're working on aged, brittle plastic ymmv. You might want to do a test drill on a panel that isn't viewable (a piece from the trunk, etc)
Gotcha640
Well-known member
Step drill or hole saw, depending on clearance behind it. If you're worried about slipping and scratching, you could put masking tape first. Harbor freight step drills have worked well for me in plastic and metal.
rlitman
Well-known member
Step drill or hole saw, depending on clearance behind it. If you're worried about slipping and scratching, you could put masking tape first. Harbor freight step drills have worked well for me in plastic and metal.
+1
Twist drill bits have a cutting angle that pulls them in. This leads to cracking. And due to another part of their nature, they make holes that aren't round in thin materials.
Step drill bits will make a round deburred (on one side) hole, and their mild rake angle prevents them from digging in and causing damage. Hole saws are good for bigger holes, but not for the 3/4" that the OP wants.
The HF step drill bits are perfect for plastic.
rlitman
Well-known member
Should I use any lubricant?
It shouldn't be needed. You'll be turning very slowly, so it shouldn't get hot. But if it makes you feel better, water wouldn't hurt. I would not try anything else.
ttpete
Well-known member
Brad point drill bits are the way to go for smaller holes. They won't cause acrylic to crack.
EdT
Well-known member
I would think a step bit like the HF ones would work great. Depending on the shape of the grill, a forstner bit might work. In any case, no matter what you decide to use, see if you can find a dead grill at a wrecking yard. It would be good to do a familiarization test on something that doesn't matter. I would bet that the grill is ABS, but it might be something else. A piece of PVC pipe might be a good test material.
I would think a step bit like the HF ones would work great. Depending on the shape of the grill, a forstner bit might work. In any case, no matter what you decide to use, see if you can find a dead grill at a wrecking yard. It would be good to do a familiarization test on something that doesn't matter. I would bet that the grill is ABS, but it might be something else. A piece of PVC pipe might be a good test material.
Good tip. I've already been practicing. Slow and easy is my mantra!
Shawn S
Well-known member
I use a 1" hole saw when drilling into my headlights and taillights for plow lights. It works very well.
shedfullatools
Well-known member
Step bit or a twist drill, if using a twist drill spin it in reverse near the end so it doesn't bite and make a mess
ez-duzit
Well-known member
I'd use a Forstner bit in a drill press.
We don't know what type of plastic but these will drill any plastics safely:
http://norsemandrill.com/Acrylic-Chipfree-Drill.php
http://norsemandrill.com/pdf/prd/norsemanAcrylic2016-1.pdf
Bradpoints can work for some, some will drill with normal 118 degree bits, some even 135 degree bits, but FORSTNER?, Lots of different kinds of plastic and I imaging some would tolerate that...............
http://norsemandrill.com/Acrylic-Chipfree-Drill.php
http://norsemandrill.com/pdf/prd/norsemanAcrylic2016-1.pdf
Bradpoints can work for some, some will drill with normal 118 degree bits, some even 135 degree bits, but FORSTNER?, Lots of different kinds of plastic and I imaging some would tolerate that...............
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matt_i
Well-known member
Two of my favorite tools are Hougen Hol-Cutters or BlairCutters. I think both of them cross the 3/4" diameter if I remember right. The Hol-Cutter is more or less its a precision-machined (think tool & cutter grinder) holesaw that's not based on a coiled bandsaw blade. The Blaircutter is a miniature annular cutter. Both can be found in sets or individually at McMaster Carr but not under those brand names, they are "precision holesaws" or something along those lines.
In any case it cuts a precision kerf and very minimal if any burr when it completes the cut.
Also excellent for sheetmetal work.
In any case it cuts a precision kerf and very minimal if any burr when it completes the cut.
Also excellent for sheetmetal work.
MayerMR
Well-known member
+1 on the Harbor Freight step drill bit. I picked one up ages ago and never really used it until recently, but I was trying to enlarge a hole the other day and didn't have the size I needed. Chucked it up in my DP and have since used it a bunch more than I thought I would on a fabrication project. I've been really pleased with the holes it cuts in both wood, aluminum, and steel. I do use cutting fluid for the metals though. That said, it cuts through like butter...been real pleased!