Re: Machine Shop

On Sat, 22 Feb 2025 17:21:55 -0500, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:

On 2/22/2025 4:06 PM, Jeff Liebermann wrote:

On Sat, 22 Feb 2025 19:58:29 GMT, cyclintom <cyclintom@yahoo.com>
wrote:
 

On Fri Nov 8 14:03:46 2024 Frank Krygowski  wrote:

It doesn't exist, Tom. You can't pop a dent out a bicycle frame tube by
riding the bike. Thinking you can is a sign of insanity.

>
If you have a slight dent in high performance steel. the tubing can revert to its natural shape under stress.

 
Tom.  The only steel that might do that is spring steel (1095, 1060,
1075, 1080, etc).  Bicycle frames are not made from spring steel.  If
they were made from spring steel, they would ride like the proverbial
wet noodle.
 
So, what's the SAE/AISI number for such a spring steel bicycle frame
and who is selling such bicycles?
<https://www.azom.com/article.aspx?ArticleID=6151>
Since you claim that you fixed the dent on YOUR bicycle, could I
trouble you for the maker and model number of this bicycle so I can
determine steel alloy that was used?  Some photos of the dent, before
and after, would also be nice.
 
Note that I'm not talking about shape memory metal alloys:
<https://en.wikipedia.org/wiki/Shape-memory_alloy>
 
I'm also not talking about hydroforming, which doesn't work at
removing dents in steel tubing without high pressure hydraulic
assistance.  It's commonly used for bending aluminum frames.  You
obviously don't have the necessary equipment in your garage workshop
because you claimed that the dent popped out after simply riding the
bicycle:
<https://www.bikeforums.net/bicycle-mechanics/919494-ding-removal.html>
 

Where the hell do you get off not knowing the properties of tempered steel and commenting on it?

 
Frank, he's all yours now.

Sorry, I'm going to disagree with you about spring steel. AFAIK there is
_no_ steel that would spontaneously cure a dent in a bicycle tube from
riding stresses. If the steel is dented, it's been stressed in that
location beyond its yield point. There's no practical way for that to
spontaneously reverse itself.

That's correct.  However, you're reading too much into my mention of
1095 steel being "spring steel".
<https://www.mcmaster.com/mvD/pdf/116/3630.pdf>
1095 is a steel alloy that can be used for making steel springs.  It
can also be used for making knife blades, where the a springy steel
makes the blade more durable.  The major difference is the steel
spring is fairly thin, while the knife blade is much thicker.  Same
spring effect, but very different products.

While Andrew knows much more than I about the applicable shop
techniques, I think you might be able to partially remove a dent in a
tube if, like a seat tube, you had access to an open end. Perhaps
forcing in a series of mandrels of increasing diameter could gradually
force the dent outward. (Something similar is done to repair dents in
the tubing of brass instruments like trumpets.) But I doubt it would
give a perfect result, and I think cosmetic repair (maybe Bondo?) would
be needed to get it really pretty.

Some kind of flexible automobile body putty (usually an epoxy) would
work.  I had the left seat stay, on my Miyata 610 touring bicycle,
repaired professionally.  I didn't paint it.  I'm sure if I had, there
would be no evidence of the repair remaining.
<https://www.learnbydestroying.com/jeffl/pics/bicycles/Miyata-610.JPG>
It's the rust colored section of the left seat stay.  Unfortunately, I
didn't see the work and cannot describe how it was done.

What Tom is describing is his usual mix of lying and fantasy and ignorance.

Yep.  After so many years of cultivating Tom's fertile imagination,
all that has grown were poisonous flowers and ugly weeds.


--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558