User Panel
User Panel
User Panel
USA
|
Posted: 4/25/2024 5:27:36 PM EDT
I need to cut a roughly 3” square hole with rounded corners to mount some lights on my truck bumper. I have a template I can trace on to the bumper. There is only about 1/4” of flange on the lights beyond the hole so I need to be careful and not cut it too big.
I have a cutting torch and plasma cutter but the bumper is powder coated and I am not wanting to damage the finish. My first thought was use a 3” hole saw and then a die grinder to cut out the corners but I wasn’t sure if there was a better way. |
|
|
|
Posted: 4/25/2024 5:30:40 PM EDT
[#1]
You could drill the corners first, then 3" whole saw, then just take out what's left with the die grinder.
|
|
|
|
|
Posted: 4/25/2024 5:35:40 PM EDT
[#2]
Quote HistoryOriginally Posted By BobbyHill: You could drill the corners first, then 3" whole saw, then just take out what's left with the die grinder. I would probably use a hole saw that provides the proper radius in all 4 corners and then make the straight cuts with a cutoff wheel in a grinder. |
|
|
|
MN, USA
|
Posted: 4/25/2024 6:11:20 PM EDT
[Last Edit: M4BlackRifle]
[#3]
Drill the four corners with 1/4" - 3/8" drill, and cut from hole to hole. A few holes in a line lets you make a starting place for a saw. Sawzall, saber saw, hack saw, 3" air compressor cut-off tool, or whatever else works for you.
Use plenty of tape to protect the finish around the cuts. |
|
|
CO, USA
|
Posted: 4/25/2024 6:47:47 PM EDT
[#4]
That big of a hole saw will not make a nice 3" hole.
As stated, drill each corner and then cut out the middle with a saw. A Jig Saw with metal cutting blade will be easiest to control and produce less heat. |
|
|
MD, USA
|
Posted: 4/26/2024 7:15:48 AM EDT
[Last Edit: jmt1991]
[#5]
Since it's such a small hole, you might have to use a jigsaw with a quality metal cutting blade.
Cover the area with masking tape and do the layout on the tape. Don't forget to paint the cut areas or you'll have corrosion working its way under your nice powder coating. Post a few pics when you get it done, I'm sure we all would like to see the finished product. |
|
|
|
Posted: 4/26/2024 7:27:32 AM EDT
[#6]
Quote HistoryOriginally Posted By number40Fan: That big of a hole saw will not make a nice 3" hole. As stated, drill each corner and then cut out the middle with a saw. A Jig Saw with metal cutting blade will be easiest to control and produce less heat. This |
|
|
|
|
Posted: 4/26/2024 7:30:53 AM EDT
[#7]
One 3" square hole in 12 ga would not be a bad job for a drill and then hacksaw.
|
|
|
|
|
Posted: 4/26/2024 7:38:42 AM EDT
[#8]
Quote HistoryOriginally Posted By M4BlackRifle: Drill the four corners with 1/4" - 3/8" drill, and cut from hole to hole. A few holes in a line lets you make a starting place for a saw. Sawzall, saber saw, hack saw, 3" air compressor cut-off tool, or whatever else works for you. Use plenty of tape to protect the finish around the cuts. Cut the straights a bit undersize and file to the line |
|
|
|
GA, USA
|
Posted: 4/26/2024 7:53:57 AM EDT
[#9]
Based on the thread title, i was gonna say use a mill.
That would be way more precise than any of the suggestions. But i think it may be overkill for the actual question. Taking off the bumper and mounting it in the mill is a lot of work for some level of precision that isn't really required. You're looking at using a couple different power tools, by hand. The cuts aren't gonna line up perfectly or be placed exactly where they need to be. Come back and clean it all up with a hand file. |
|
|
|
Posted: 4/26/2024 11:59:53 AM EDT
[#10]
Use a plasma arc cutter, then clean it up with a grinding wheel.
|
|
|
|
|
Posted: 4/26/2024 6:56:48 PM EDT
[Last Edit: paul463]
[#11]
Drill the corners, saw the sides.
FWIW, a hole saw will cut an acceptable hole if you first use the holesaw to put a hole in a 3/4" thick piece of hardwood and then clamp the wood to your part to use as a guide for the saw. It tames down the wobblies quite a bit. |
|
|
|
MI, USA
|
Posted: 4/27/2024 9:54:06 PM EDT
[#12]
air saw would probably be good here.
|
|
|
|
Posted: 5/1/2024 5:13:28 AM EDT
[Last Edit: MethaneMover]
[#13]
Drill the corners and mark a bright line between the holes. Then use a skinny wheel on the side grinder to plunge in, the larger diameter wheel the better. The goal is to cut the whole length without moving the grinder, this prevents you from wandering in the cut.
You'll get a straight line very quickly. May have to touch up the corners. That said- a plasma torch, a soapstone and a speed square will take you a long ways down this road. |
|
|
|
|
Posted: 5/2/2024 1:47:08 PM EDT
[#14]
Originally Posted By MethaneMover: Drill the corners and mark a bright line between the holes. Then use a skinny wheel on the side grinder to plunge in, the larger diameter wheel the better. The goal is to cut the whole length without moving the grinder, this prevents you from wandering in the cut. You'll get a straight line very quickly. May have to touch up the corners. That said- a plasma torch, a soapstone and a speed square will take you a long ways down this road. This all day. Also do a test run on some other material. Doesn’t even have to be metal. |
|
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
