Re: RE: Re: Machine Shop

On 3/5/2025 1:01 PM, cyclintom wrote:

On Tue Mar 4 12:03:42 2025 Frank Krygowski  wrote:

On 3/4/2025 12:44 AM, AMuzi wrote:

>
For a typical dent, this Waterford for example:
http://www.yellowjersey.org/wfd12a.jpg
>
the tube is rolled to reform the greater part of the deformation:
>
http://www.yellowjersey.org/wfd12b.jpg
>
then the remaining low spots are filled with polyester bondo or with
metal (brass, silver, lead. I use lead):
>
http://www.yellowjersey.org/wfd12c.jpg
>
and finished:
>
http://www.yellowjersey.org/wfd12e.jpg

>
Could you explain what's meant by "the tube is rolled"? As I said
earlier, I'd thought the first step would be pushing a mandrel through
(if the dent was in the seatpost) to partially push out the dent. Of
course, that wouldn't work except on a seat tube, and I suppose would
still require filling. Are you skipping that step entirely?
>
BTW, my antique BMW has a slight dent in the top of the gas tank,
apparently from something falling onto it. I've heard of "paintless dent
repair" for car bodies and wondered about it, but never looked deeply
into it. I gather that some skilled body workers can do pretty well at
pushing dents back out from the underside.

    Have you got this now? Skilled body workers sometimes find a dent that they push on from the opposite side and the dent pops out. Wait a minute - you are all saying that is impossible.

Having done a lot of that work myself (less panel work than bicycle tubes, but still plenty) yes, it can look fairly good if done judiciously. There is always extraneous damage, usually with the panel being slightly larger in area after that process. For a small dent, that change is hard to see but working large dents will change the shape of the panel overall even though the damaged area looks smooth.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971