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How to 'roll out' a dent in aluminum top tube?

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How to 'roll out' a dent in aluminum top tube?

Old 10-07-19, 01:40 PM
  #1  
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How to 'roll out' a dent in aluminum top tube?

Is this even possible with aluminum? It's a Cannondale 2.8 frame from the '90's. I've heard others speak of rolling out a dent in steel but I'm not even sure how that's done?
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Old 10-07-19, 01:43 PM
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I am not certain that it is wise to work the material any more than the dent has done, for fear of making it brittle or starting cracks. If it were my bike I would fill it with Bondo and paint over it, or leave it as a battle scar.
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Old 10-07-19, 01:43 PM
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I saw a video about that on a steel bike but it didn't completely iron out the dent, plus it wrecked the paint.
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Old 10-07-19, 01:45 PM
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Originally Posted by dsbrantjr View Post
I am not certain that it is wise to work the material any more than the dent has done, for fear of making it brittle or starting cracks. If it were my bike I would fill it with Bondo and paint over it, or leave it as a battle scar.
Or put a sticker over it
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Old 10-07-19, 01:50 PM
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Non modern high strength steels take fairly well to being bent twice. (Witness all the bent and successfully straightened frames over the past century.) Aluminum far less so. Rolling out a dent might just be a very good crack starter. Then again, if the dent is in a low stress area, with al the material in the typical large diameter, thick wall tube, the stresses are pretty low.

If the dent is in the middle of the top tube or seat tube and in a very visible place, well I might. But I'd check it often.

Ben
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Old 10-07-19, 02:07 PM
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I watched the old man pull a dent out on a car, tack welded the rod then pulled it out

i thought of devising a way for a bike, small dent on a repco tri-A frame, might be worth doing


Dent pulling aluminum..
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Old 10-07-19, 02:37 PM
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Originally Posted by le mans View Post
Or put a sticker over it
That's the way I'm leaning! Maybe one of my granddaughter's flashy band-aids!
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Old 10-07-19, 02:39 PM
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You can use a simple slide hammer to pull the welded on pin instead of those pulling devices in the video. Those tripods look cool but won't work well on a tube.
Using a pin held on with epoxy might work. No spot welder needed, no extra heat, less repainting, etc.

Lots of hail damage repair businesses use suction on hail dented car panels.
Or just set it in the sun in the back seat of a car with a black interior. It may just pop out.
I've seen black cars with hail damage self repair in the summer heat.
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Old 10-07-19, 02:42 PM
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Thanks all! This is a '96 R900, which is nude polished aluminum, no paint involved.
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Old 10-07-19, 09:16 PM
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Thus the cost of a temporary frame material is found out As said steel is vastly more able to withstand more then a few bendings. Case in point are fork blades that get bent about three times at the least yet last for tens of thousands of miles.

I would do as others have suggested. Leave the Al top tube dent as it and cosmetically hide it if it bothers you. Andy
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Old 10-07-19, 09:26 PM
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Maybe some useful tips in here.

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Old 10-07-19, 09:43 PM
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Originally Posted by dsbrantjr View Post
I am not certain that it is wise to work the material any more than the dent has done, for fear of making it brittle or starting cracks. If it were my bike I would fill it with Bondo and paint over it, or leave it as a battle scar.
+100

Not sure that tuba repair techniques, suitable for a ductile, malleable metal like brass, is apropos. Nor is car-body repair techniques for non-structural aluminum the thing (IMHO). Plus, if you use the techique in the video, you have to remove the welded-on aluminum stud. But it is interesting to hear the guy describe how factory aluminum is softer, and is heat treated to get harder (and more brittle, unfortunately).

Aluminum work hardens and will crack if cold-worked too much. Leave it.

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Old 10-07-19, 10:02 PM
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Originally Posted by WizardOfBoz View Post
+100

Not sure that tuba repair techniques, suitable for a ductile, malleable metal like brass, is apropos. Nor is car-body repair techniques for non-structural aluminum the thing (IMHO). Plus, if you use the techique in the video, you have to remove the welded-on aluminum stud. But it is interesting to hear the guy describe how factory aluminum is softer, and is heat treated to get harder (and more brittle, unfortunately).

Aluminum work hardens and will crack if cold-worked too much. Leave it.
Indeed, brass repair techniques completely revolve around the properties of that material. I just offered it for amusement.
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Old 10-08-19, 07:27 AM
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Gresp15C, I'm sure that someone, somewhere, has made a bike out of a recycled saxophone or something.
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Old 10-08-19, 01:28 PM
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I have a really cheap alumin(i)um frame, an Alý, with a couple of noticeable dents. It's 20 years old with 100K miles on it. I do nothing about them. I suspect that bending the metal again would make it weaker, if not break it outright. I'm no expert.
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Old 10-09-19, 02:15 PM
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Originally Posted by arthur peabody View Post
i have a really cheap alumin(i)um frame, an alý, with a couple of noticeable dents. It's 20 years old with 100k miles on it. I do nothing about them. I suspect that bending the metal again would make it weaker, if not break it outright. I'm no expert.
+1 Not an expert, but I have some general and specific knowledge in the area. You are correct, sir.
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