# Want to remove big dent in down tube



## fattommy (Oct 17, 2013)

I'm wondering if there's a way to get a big dent in a girls bike down tube to pop up flush. Actually there are three dents.1. The first one, then 2. and 3. crushed sides from someone using vice grips to try to squeeze across the tube to pop the first dent out.
 I don't care if the paint gets wasted.


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## Andrew Gorman (Oct 17, 2013)

Frame blocks.  It could take some force to get gas pipe horsed back into shape, but these are the tools to use.  I'ts been decades since I used something like this to smooth out a 531 Dawes frame, but it worked.  Use LOTS of oil.
http://www.paragonmachineworks.com/cgi-bin/commerce.cgi?search=action&category=TB07


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## Nickinator (Oct 17, 2013)

my idea would be to make a solid long rod with a sloped edge that fits snug into the downtube heat up each spot on the downtube that you want straitened with a blow torch and hammer down the rod making the dents go away by force.  just an idea i had brewing.

Nick.



fattommy said:


> I'm wondering if there's a way to get a big dent in a girls bike down tube to pop up flush. Actually there are three dents.1. The first one, then 2. and 3. crushed sides from someone using vice grips to try to squeeze across the tube to pop the first dent out.
> I don't care if the paint gets wasted.


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## Obi-Wan Schwinnobi (Oct 17, 2013)

fattommy said:


> I'm wondering if there's a way to get a big dent in a girls bike down tube to pop up flush. Actually there are three dents.1. The first one, then 2. and 3. crushed sides from someone using vice grips to try to squeeze across the tube to pop the first dent out.
> I don't care if the paint gets wasted.




Slide hammer?


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## fattommy (Oct 17, 2013)

Andrew Gorman said:


> Frame blocks.  It could take some force to get gas pipe horsed back into shape, but these are the tools to use.  I'ts been decades since I used something like this to smooth out a 531 Dawes frame, but it worked.  Use LOTS of oil.
> http://www.paragonmachineworks.com/cgi-bin/commerce.cgi?search=action&category=TB07




What is the concept?  The dented pipe is not round so clamping in the blocks forces it back round, thus squeezing out the dents a little at a time?  These are pretty deep dents we're talking about.


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## fattommy (Oct 17, 2013)

Obi-Wan Schwinnobi said:


> Slide hammer?




That sounds like it might work.


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## fattommy (Oct 17, 2013)

Nickinator said:


> my idea would be to make a solid long rod with a sloped edge that fits snug into the downtube heat up each spot on the downtube that you want straitened with a blow torch and hammer down the rod making the dents go away by force.  just an idea i had brewing.
> 
> Nick.




Can't get inside the tube Nick.  Thanks.


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## Obi-Wan Schwinnobi (Oct 18, 2013)

fattommy said:


> That sounds like it might work.




Also use part of nicks advice Whist  using slide. Heat with torch and gently start using slide. Even if there is slight dimple you can fill it with jb weld and sand


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## fattommy (Oct 18, 2013)

Here’s the problem.
http://i.imgur.com/J1mbykY.jpg
Andrerw is right, frame blocks are the way to do this job IF the down tube is straight.  Because the girls bike has a curved down tube, straight blocks probably won’t work.
It might be possible to shrink the dents out.  Shrinking involves heating the metal red hot along the edge of the depression, then shocking the steel by immediately applying a wet rag to cool the metal fast. 
http://i.imgur.com/j7W7n1n.jpg
A lot of the shallower side dents were reduced using this method, but after many attempts to bring the big dent up, I decided to take a different approach.
Using the torch to heat the metal along the edge of the dent, I tapped the hot edge with a hammer to move the metal back into round.  The dent started to come up.  I did this in a series if successive steps until each additional step didn’t do that much.  Then I went to the other side and did the same thing.  Then to the big dent without much luck there.  I think this is the way frame blocks would work, except without the heat destroying the paint.  When the metal is hot, you can see the edge of the dent where it is not round.  By tapping along the edge, you flow the metal back where it was before it was dented.  
Don't worry the cardboard boxes were 15 feet away.
http://i.imgur.com/yr5ftSM.jpg
Because the big dent was crimped so deep, the metal didn’t go back round very much.
Becoming frustrated, I drilled a small hole under the big dent and used a punch through the hole to push the dent up.
http://i.imgur.com/v4AJWNU.jpg
That worked pretty good.
http://i.imgur.com/Cmh1jeX.jpg
Later, the hole was welded closed and filed down flush.
You know what this is.
http://i.imgur.com/NyghadG.jpg
As I couldn’t get it to come out perfectly smooth, some filler was added.
http://i.imgur.com/8Qb2gGM.jpg
Then Primer.  Viola!  
You could probably do the same job without the torch, just by drilling 3 holes and punching the dents out one at a time, then file and Bondo and primer.
Hope you found this interesting.  Tommy


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## Andrew Gorman (Oct 18, 2013)

That's a crafty way to fix the problem!  I like it.


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## hoofhearted (Oct 19, 2013)

*Da Ding ... Sheeza No More !!!*

Excellent Processing .. Tommy !!! 

I also like how you made a journal of your efforts .. with fotos !!!  

BRAVISSIMO !!!


................  patric


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## Boris (Oct 19, 2013)

Thanks Tommy, I have the exact same problem. My class instructors suggestion was to build bridge with a hole to thread a bolt, weld the bolt end to the dent, then unscrew the bolt, thus pulling the dent with it, then breaking the weld, and cleaning up the area. I haven't tried it yet, but your way sounds a little more direct.


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## fattommy (Oct 19, 2013)

Dave Marko said:


> Thanks Tommy, I have the exact same problem. My class instructors suggestion was to build bridge with a hole to thread a bolt, weld the bolt end to the dent, then unscrew the bolt, thus pulling the dent with it, then breaking the weld, and cleaning up the area. I haven't tried it yet, but your way sounds a little more direct.




That's a very good idea.  You could use a 1/2 pipe with a hole for the bridge.


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## SJ_BIKER (Nov 25, 2013)

*i like this idea for some handlebars i have*



Nickinator said:


> my idea would be to make a solid long rod with a sloped edge that fits snug into the downtube heat up each spot on the downtube that you want straitened with a blow torch and hammer down the rod making the dents go away by force.  just an idea i had brewing.
> 
> Nick.



i actually like this idea to get dents out of some braced handlebars i acquired on one of the handles


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## GiovanniLiCalsi (Nov 25, 2013)

Heat the dented area cherry-red then take it to a body shop that has a stud spot welder machine. Have the stud welded onto the dent and hammer it out.

http://youtu.be/vEyE8PibVDs


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