Re: Small Part Machining

John Fortes

June 30, 2011 at 10:25 AM

It does not sound from the original description that it was the bolt that
failed. It sounds like the rod that was tapped for the bolt to go into
failed. If I understand your description of the broken part, you could try
looking at McMaster-Carr for a hardened SS dowel pin and then get it tapped
to the correct thread of the bolt that you have. The higher the
ultimate yield strength the better. No need to go cheap if all you need is
one.

On Thu, Jun 30, 2011 at 10:08 AM, Shane Gibson wrote:

>
> I agree with what Jon says. I've broken a seat bolt in the past (during
> rather rigorous mountain biking ... and the results ... were very, very
> painful). I searched high and low for a replacement bolt - and found that
> Chown Hardware in Portland, on SE Stark carries a very very wide selection
> of high quality bolts. I rode using that replacement bolt from Chown for 5
> more years of hard use before retiring that bike.
>
> You do NOT want your seat bolt to break at the wrong time. Trust me.
>
> ~~shane
>
> --
> "Opportunities multiply as they are seized." - Sun Tzu
>
>
>
> On Thu, Jun 30, 2011 at 9:26 AM, Jon Myers wrote:
>
>> I would be very careful picking the material for this part. The parts
>> around the seat post tend to be very highly stressed. Often these parts are
>> a high strength alloy steel. These parts are typically machined in an
>> annealed condition when it is softer and easier to machine. Then the part
>> is then heat treated to give it a good mix of hardness, strength and
>> ductility. A steel part that is heat treated to full hard can be up to 4
>> times as strong as the same part in an annealed (soft) condition.
>> -Jon
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>
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--
John P. Fortes

Racing for a cure: http://www.active.com/donate/cycle11national/JFortes