Rock chip with a burr!

M

Manhattan

Member
Joined
Oct 15, 2018
Messages
37
Reaction score
17
Actually, I doubt a rock did this. the edges of the chip are crisp and I can't imagine a rock cutting into the metal like this. I'm guessing it was a piece of metal. Either way, it's ugly.

The paint chip looks normal. It was the snag on the microfiber wash mitt that told me this was not the typical chip. I verified that it is not paint, i.e. a sharp leftover edge. My iPhone did a decent job confirming this.

So, what do I do? I don't want tap the shard flat - that will leave an odd blemish - after touchup - at best; a good spot for rust to form, at worst. Part of me wants to get out the Dremel and that fine-pointed stone and (gulp) grind that burr away. The other part of me keeps saying, "Dude, this is a 2023 BMW and you are not that good."

Thoughts?
(blue tape to give the camera something to focus on)
Screenshot 2026-04-14 at 8.50.30 AM copy.png

If I decide to have pro do the repair, any suggestions for a mobile paint repair pro in Atlanta? I'd rather find an independent guy - and not Colors on Parade or similar franchise. Also, don't want to have the dealership handle it - they're just going to call the guy I'm trying to find.

Thanks!
 
Last edited:
I think you gotta do the Dremel, put plenty of tape real close to the chip so that only the burr is exposed, and try and get a magnifying light on it so you can see what you're doing.

PS I don't see why a rock couldn't have done that.
 
Thanks @Setec Astronomy - good call on the tape.

That leading edge of the chip is so sharp, and the way the metal was peeled. But, I'm a branding guy. I'm more qualified to name the chip than determine its cause.
 
You could also try a sanding block, if you've got it all taped off, that might allow you to go a little more evenly and not have an oops. Or a stone, like a sharpening stone.
 
Touch up specialist will add paint with clear and then sand back buff and you wouldn't even know.

That's what you need
 
^That^ has to come after grinding/sanding down the burr - it is above the surface and sharp, i.e. snags towels, etc. But your point may still hold - a touch-up guy has surely dealt with this before, and has sanding blocks, files, a Dremel...
 
A Dremel and some touch up paint was my first thought too. However, as already mentioned it would take a very steady hand and a tiny grinding tip.
I'd have to look at my kit, but I don't recall having a tip small enough to do that type of work. Doesn't mean one doesn't exist, just it may not be one found amongst those you get with the tools.

I could see a small rock doing that. The right shape and the closing velocities of both the rock and car can do some crazy things. The good news is the metal on the outside of the A-pillar may be fairly soft (aluminum?) and would grind away pretty quickly/easily.
 
I just assumed the A-pillar would be steal. Man, AL would make this a much simpler project.

Any suggestions for a source of good touch-up paint?
 
Manhattan said:
I just assumed the A-pillar would be steal. Man, AL would make this a much simpler project.
Click to expand...

It may not be. My thought was the structural A-Pillar portion of of the unibody structure would be some form of hardened steel, but the painted exterior piece that extends from the front quarter panel, over the doors, and down the c-pillar might be a separate piece which is attached to the unibody and made from something else, or at least a softer grade of metal.
 
Confirmed the A-pillar is steel... the magnetic work light snapped to it with force ;-) Of course, the base of the light was taped to protect the paint.

I was able to eliminate the burr and do no further harm to the patient. Sorry, but I did feel like a surgeon - work light positioned over the "wound", (my garage already has ten 8' LED lights on the ceiling), 2.5X readers, the blue tape even looked like those surgical towels...

I've played with rotary tools enough to know how they can jump, hence the excessive tape and a two-handed approach - the left forearm on the A-pillar doing 95% of the stabilizing, the right just delicately guiding/touching the burr. The Xacto blade helped to "feel" the metal - gauging the direction, angle, etc.

1st pic is the untouched burr.
2nd pic, you can see how the burr kinda curled over the tip of the blade.
3rd pic is just the corner of the chip where the burr was - NOT the same image as the 3rd pic; I re-taped tighter around just the burr - 85% gone in that pic.
4th pic shows the smooth divot, no damage to surrounding paint.

I added a bit of primer to the bare metal - well below the level of the paint, i.e. room for color and clear

2.jpg
 
That's fantastic.

Was the burr small enough/thin enough to remove with the Xacto or did you have to totally grind it off. How small of a Dremel tip did you have to use to smooth everything out? It doesn't look like there is any scuffing on the tape from grinding so it had to be really small, and your hands very steady!
 
The base of the burr was pretty thick - relatively speaking. Too thick to cut with a razor. I was able to grind away all of the burr, i.e. to the level of the rest of the chip/divot. I used a 3.4mm Dremel bit (#997) and the tool set to 4.

Imagine holding the Dremel in your left hand, palm like you might hold the forestock (?) of a rifle/shotgun (assuming you're right-handed). That forearm was laying on the A-pillar just down from the chip. That allowed me hold the tip over the area with a good bit of force/stability. Even if the stone caught and tried to jump, it couldn't... well, much. With my right hand, I moved the tool and my left hand - just grazing, bumping the burr and assessing. Yeah, tedious, but I'm not actually a surgeon ;-)

I liked the almost 90 degree edge on this bit. It gave me a sharper angle of attack - oddly more precise than a rounded tip

Screenshot 2026-04-30 at 11.38.39 AM.png
 
Looks like a bullet ricochet off your car. I see this oall the time. Your lucky it didn't penetrate
 
Manhattan said:
The base of the burr was pretty thick - relatively speaking. Too thick to cut with a razor. I was able to grind away all of the burr, i.e. to the level of the rest of the chip/divot. I used a 3.4mm Dremel bit (#997) and the tool set to 4.

Imagine holding the Dremel in your left hand, palm like you might hold the forestock (?) of a rifle/shotgun (assuming you're right-handed). That forearm was laying on the A-pillar just down from the chip. That allowed me hold the tip over the area with a good bit of force/stability. Even if the stone caught and tried to jump, it couldn't... well, much. With my right hand, I moved the tool and my left hand - just grazing, bumping the burr and assessing. Yeah, tedious, but I'm not actually a surgeon ;-)

I liked the almost 90 degree edge on this bit. It gave me a sharper angle of attack - oddly more precise than a rounded tip

View attachment 140214
Click to expand...
Like a filling from the Dentist. Well done!
 
You must log in or register to reply here.
Back
Top