Roof is in temporary 1k primer to stop flash rust as I stripped it for when the car goes for blasting (as the roof isn't getting blasted). Roof was really good no dents from what I could see. Car is on a jig and I hadwas working on making templates for the sound deadening and using some c clamps during this process. Anyway I forgot they were still there, turned the car over on the jig. The clamps fell from where they were hooked on on the floor and hit the inside of the roof. What a **** idiot I am! Checking the general shape of the roof using splines I think I'm ok. It's just some very sharp dents which I have no idea how to tackle as I think they must have put a quite a bit of stretch in...

How on earth do I tackle this? Here's some photos
Inside (where impact happened)


Outside:

onthames wrote:Roof is in temporary 1k primer to stop flash rust as I stripped it for when the car goes for blasting (as the roof isn't getting blasted). Roof was really good no dents from what I could see. Car is on a jig and I hadwas working on making templates for the sound deadening and using some c clamps during this process. Anyway I forgot they were still there, turned the car over on the jig. The clamps fell from where they were hooked on on the floor and hit the inside of the roof. What a idiot I am! Checking the general shape of the roof using splines I think I'm ok. It's just some very sharp dents which I have no idea how to tackle as I think they must have put a quite a bit of stretch in...

How on earth do I tackle this? Here's some photos
Inside (where impact happened)

Outside:

Looking through my tools I have a dolly which does match the profile quite well and a flat face planishing hammer (which I've never used!!).
I've just bought an aluminium hammer with swappable pointed tips which I presume I will need to hammer out the sharp centre of the impact. Advice appreciated im panicking!

I'll give you the bad news first: there's no way you can fix all this without some bodywork, and repriming.
try some careful hammer and dolly work. if you're lucky, it won't need shrinking but a couple of those look a bit stretched, its hard to be sure from a picture
i've had a lot of success using one of those copper pin stud guns, which came with a shrinking tip, to take out stretched dents on a rook from severe hail. not the same as what you're dealing with, but somewhat similar.
only do heat shrinking as a last resort and do a test run on some junk if you've never done it before.
with some patience and careful taps, you might be able to straighten this out. no matter what, however, i don't think this is fixable without some body filler and more primer.

Looking through my tools I have a dolly which does match the profile quite well and a flat face planishing hammer (which I've never used!!).
I've just bought an aluminium hammer with swappable pointed tips which I presume I will need to hammer out the sharp centre of the impact. Advice appreciated im panicking!

support the dented are with the dolly, and LIGHTLY tap on the high part of the dent.
the best way i can describe the technique is to "bounce" the hammer, something like dribbling a basketball. don't make forceful, dead blow swings! swinging a body hammer is nothing like driving nails with a carpenter hammer.
the idea is that you are trying to give the metal a bit of a shock, and if done in the right place, it will actually start to jump back into place on its own. you can use extremely light taps on and around the dent, and you can hear the tight spots, kind of like a drum. if you start to hear the hammer hitting the dolly STOP. this will squish and stretch the metal, making the problem worse.
you're just using the dolly as support, and you're tapping with the hammer as a tension reliever. you're not shaping the metal back into place, you are removing tension in the metal so it can move back into place on it's own.
hope this helps!

Had a go today, seem to have got most of them but one of them has flipped and gone low. I started with the flat planishing hammer and a dolly underneath, hitting the high directly with firm pressure from the dolly. This seemed to work and brought it down but the very centre of the high was still proud so I switched to a much smaller knock down tool right on the centre. Seemed to work for all but one, this one flipped, almost as if it didn't want to cold shrink and just flipped into a low instead of a high! Running a body file over it matched to the shape of the roof I don't see much (if any) of a donut high around the low, which is confusing me. I just have a low where the high once was. I think the most severe dent would need heat shrinking however I don't want to open that can of worms. As long as its low and a skim over will fix it then I'm happy with that. Will post some photos tomorrow.

I sprayed on some guide coat and sanded it off on each spot. 3 of the 5 seem very good so I'm happy about that. The other 2 which were the more sharp dents have gone low but I think a skim of filler will sort it. Any thoughts?

For the dents that are deeper than the others, there is more stretching. You'll have more luck with starting off with either: a soft dolly and hard hammer, or soft hammer and hard dolly. That way the metal can 'give' a little and cold shrink. Once you get it very close, you can switch to light planishing.

chopolds wrote:For the dents that are deeper than the others, there is more stretching. You'll have more luck with starting off with either: a soft dolly and hard hammer, or soft hammer and hard dolly. That way the metal can 'give' a little and cold shrink. Once you get it very close, you can switch to light planishing.

I used a hard plastic tap down hammer on the peak of the high with a heavy dolly behind however it didn't want to shrink and eventually went low as you see in the photos.

It's OK, just need more hammering. If you had experience with heat shrinking, I'd say do that, or use a shrinking disc, or stud gun to shrink the worse spots. But the way you're hammering will work as well, just takes quite a bit longer.