Hole cutting advice

[RODRIG3911]

What's up fellas! I'd like to cut a couple holes in my powder coated bumper for lights, without jacking up the finish. I'm kinda hesitant to do it because my bumper looks pretty nice.

How can I cut the holes and have it still look good? I'm THINKING maybe drill a pilot hole and using a jig saw. Is there a better way? Should I just not mess with it? Here's a pic of my Bronco with the bumper.

 

[Speedrdr]

How large does the hole need to be? There is a “device” called a hole puller that I have used to make a hole in a chrome mercury bumper for a C B antenna. I drilled a 1/2” hole through the bumper and put one piece on the back side of the bumper and the other one on the outside and put a bolt through the outside hole and threaded into the other. Just tighten up the bolt and it pulls/cuts a nice round hole. The hole puller I used pulled a 2” hole.
I’ll try and find a link.

Randy

 

[Speedrdr]

Something like this, maybe.

R

 

[jeffncs]

I knew these as “Knockout Punches”. This pic came from Harbor Freight.




The idea is that the cutting side pulls into the round female end making a clean, circular hole.

 

[jeffncs]

Something like this, maybe.

R

I don’t think that’s what he needs. If he wants concentric holes in sheet metal, knockout punches are the ticket.

HOWEVER, they’re only good for sheet metal. If you’re looking at thicker steel, you’ll need a hole saw.

 

[jeffncs]

These work up to 3.5mm thickness.

https://www.amazon.com/dp/B084WWJZH4/?tag=classicbroncos-20

 

[nvrstuk]

A GOOD hole saw (and there is a HUGE difference in quality) and then finish the cut edge with a good whatever to seal it the edge of the cut powder coat to the steel. This is important because the hole saw will probably generate enough heat to affect the bond of the powder coating. Then try to use a grommet to lap over that cut edge.

 

[73azbronco]

I tried those harbor freight hole punches, they would not go through the sheet metal on the dash.

I would say maybe mount them on brackets vs trying to cut and weaken the bumper?

 

[Speedrdr]

I knew these as “Knockout Punches”. This pic came from Harbor Freight.

View attachment 908930


The idea is that the cutting side pulls into the round female end making a clean, circular hole.

^^^^^ this is what I was trying to describe (very poorly) in my comment. They do indeed work well. Just takes time and muscle.

R

 

[Yeller]

A hole saw will work and do a clean job of it. Use water or wd40 as a coolant and it will stay nice and cool not effecting rhr powder coat.

As for cutters These have become my go too if the size you need isn’t available their regular hole saws are pretty great too.

 

[BOBS 2 68S]

Square or round lights?
For square lights drill the 4 corners and use a body saw and take your time

 

[bigmuddy]

A GOOD hole saw (and there is a HUGE difference in quality) and then finish the cut edge with a good whatever to seal it the edge of the cut powder coat to the steel. This is important because the hole saw will probably generate enough heat to affect the bond of the powder coating. Then try to use a grommet to lap over that cut edge.

Beat me to it. My concern would be sealing up the cut edge as it will likely delaminate and peel at some later point, if you don't make sure the edges stay sealed from moisture. Might still do it but I would seal with something and then add a grommet if that works for the look you are going for?

 

[Yeller]

Beat me to it. My concern would be sealing up the cut edge as it will likely delaminate and peel at some later point, if you don't make sure the edges stay sealed from moisture. Might still do it but I would seal with something and then add a grommet if that works for the look you are going for?

clear or color match spray paint works pretty good for this. Especially if you keep the cut cool when cutting. Spray the exposed metal and immediately wipe off the excess from the powder coated surface.

 

[nvrstuk]

If you use a grommet to mount the light or whatever, what are the thoughts for using liquid electrical tape for sealing that raw edge (good stuff)? I have used it before for sealing edges of paint and water never gets thru. Obviously you have to hide that liquid tape stuff tho!!

 

[ba123]

Yeah, hole saw if it’s round, but need to go sloooooow, as in dril slow, stop…drill slow, stop. Do not be in a hurry, do not overheat the bit or the bumper and then you’d need to make sure you cover the edges with something like said to keep it form peeling/chipping as it will and hopefully you have a bezel that covers a little.

If rectangular, I’d use a cutting disc, no way on a jigsaw. You’d screw is all up.

 

[RODRIG3911]

How large does the hole need to be? There is a “device” called a hole puller that I have used to make a hole in a chrome mercury bumper for a C B antenna. I drilled a 1/2” hole through the bumper and put one piece on the back side of the bumper and the other one on the outside and put a bolt through the outside hole and threaded into the other. Just tighten up the bolt and it pulls/cuts a nice round hole. The hole puller I used pulled a 2” hole.
I’ll try and find a link.

Randy

Thanks Randy. I used one of those to make the hole in my new rear quarter panel for fuel. My bumper I believe has 1/4" steal though.... the hole is about 3"x5"

 

[RODRIG3911]

I knew these as “Knockout Punches”. This pic came from Harbor Freight.

View attachment 908930


The idea is that the cutting side pulls into the round female end making a clean, circular hole.

I have one that I bought for my rear quarter panel fuel inlet. Would it work on 1/4" steel though?

 

[RODRIG3911]

Square or round lights?
For square lights drill the 4 corners and use a body saw and take your time

Rectangle. Good idea on the 4pilot holes

 

[RODRIG3911]

Yeah, hole saw if it’s round, but need to go sloooooow, as in dril slow, stop…drill slow, stop. Do not be in a hurry, do not overheat the bit or the bumper and then you’d need to make sure you cover the edges with something like said to keep it form peeling/chipping as it will and hopefully you have a bezel that covers a little.

If rectangular, I’d use a cutting disc, no way on a jigsaw. You’d screw is all up.

Sounds like maybe I should Just leave it alone . I was thinking of bending some tubing instead, weld it onto the bumper, and mount some lights on it. The drilling with power coating might not work too well

 

[Speedrdr]

Thanks Randy. I used one of those to make the hole in my new rear quarter panel for fuel. My bumper I believe has 1/4" steal though.... the hole is about 3"x5"

Yeah, that round hole puller ain’t gonna 1)cut 1/4” steel OR 2)make a rectangular hole. Lol

Randy