What Die Grinder bit to use. Need to enlarge antenna hole in fender

[4mulas]

Hi there, don’t do much metal or body work so looking for what recommendations folks have for die grinder bits to enlarge my antenna hole. It was radio delete car that the previous owner put a radio in and aftermarket antenna. The hole is not what factory mopar antenna uses so I’m changing the antenna to stock and getting rid of the crappy aftermarket one.

fortunately the hole the made is near the stock location, I just have to enlarge it to fit the new antenna.

I can only think of using a die grinder or dremel like tool for this and would like recommendations on a good bit to use that maybe won’t create too much heat. I have both the die grinder and dremel.

‘’thanks!

 

[pnora]

Tape the area and use a carbide cutter. It will cut easily with little heat. Just go slow and just remove whats needed for fitment.

 

[Sahara]

I can only say what works for me; others may have other, better tips.
I find it easier to keep the hole round if you use the largest diameter burr that you have. Small burrs will want to make a raggedy looking hole; if you use a larger burr it is easier to make the gentle radius required. I’m not sure that a dremel has enough torque to effectively spin a large diameter burr.

 

[dadsbee]

Go hit up an electrician for his Greenlee unibit / step cutter to get it to the correct diameter. You'll be done in 15 seconds.

 

[4mulas]

Go hit up an electrician for his Greenlee unibit / step cutter to get it to the correct diameter. You'll be done in 15 seconds.

Thought of those but I think the problem is that the existing hole is not centered to where I want the finished product to be? Not sure you could use that for this application?

 

[dadsbee]

I hog sideways with unibits all the time... but I'd practice on something first! Hey, it's only a fender.. LOL

 

[RemCharger]

I hog sideways with unibits all the time... but I'd practice on something first! Hey, it's only a fender.. LOL

And an A body one to boot lol..
I thought uni bits only went to about 1"

 

[4mulas]

I hog sideways with unibits all the time... but I'd practice on something first! Hey, it's only a fender.. LOL

Hard to see in the photo I posted where it starts behind the stencil. I’m afraid my skills on the metal tools is definitely not up to your aircraft making abilities! I wouldn’t trust myself to try the sideways shuffle on a freshly painted fender. YIKES!

 

[khryslerkid]

Stop by your local Lowe's and get a sanding mandrel. As mentioned above tape the area incase of a slip.

 

[dadsbee]

And an A body one to boot lol..
I thought uni bits only went to about 1"

I've got some up to about 1 3/8" Greenlee Tools has all sorts of sizes for doing junction and panel boxes.

 

[khryslerkid]

I've got some up to about 1 3/8" Greenlee Tools has all sorts of sizes for doing junction and panel boxes.

When you say Greenlee I think of these knock-outs. Thing is you have to be able to get to the opposite side.

 

[dadsbee]

Greenlee makes more than punches.. they make unibits in large sizes as well.

 

[1967coronet]

Carbide bits can grab and jump if you do not have enough rpms.
For this job I like khryslerkids dremel and sanding drums idea.

 

[747mopar]

Tape the area and use a carbide cutter. It will cut easily with little heat. Just go slow and just remove whats needed for fitment.

I agree, no burs on the bottom and little heat to blister the paint.

 

[toolmanmike]

Hi there, don’t do much metal or body work so looking for what recommendations folks have for die grinder bits to enlarge my antenna hole. It was radio delete car that the previous owner put a radio in and aftermarket antenna. The hole is not what factory mopar antenna uses so I’m changing the antenna to stock and getting rid of the crappy aftermarket one.

fortunately the hole the made is near the stock location, I just have to enlarge it to fit the new antenna.

I can only think of using a die grinder or dremel like tool for this and would like recommendations on a good bit to use that maybe won’t create too much heat. I have both the die grinder and dremel.

‘’thanks!

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View attachment 1424664

How much bigger? say 1" to 1 1/4" ? I wouldn't mess with a die grinder or drum sander. They are way too hard to control in a hole like that. A step bit would work well.

 

[Daves69]

A step bit would work well.

I think he needs to offset from the current hole center.

 

[Daves69]

Maybe get it close with a carbide cutter and clean it up with a drum sander.

 

[4mulas]

I ended up using a double cut carbide burr 1/4” x 3/4. Worked like a charm with light gradual passes. I etched the paint first to creat a sharp edge to prevent excess chipping etc…
the metal stayed nice and cool. I think a stone/drum sander would have taken a long time and created a lot of heat. Made a little bed of tape, sticky side up, to catch chips and filings from going into the bottom of the fender.