Mavic CXP-30 RIm Cracks

[Rapunzel]

In the process of rebuilding one of the CPX-30 rims, I discovered that the sharp edges around the
spoke hole is a stress riser that caused a crack to develop around the spoke hole rendering this rim
unsafe to use.

When I looked at my other CXP-30 rims, I noticed the same manufacturing problem. Out came the file
and I removed all the sharp edges from the spoke holes before building the wheel. This should stop
the possibility of stress cracks due to the sharp edges.

Most mechanical part drawings are noted with, "Break All Sharp Edges." for this reason.

I wonder if other rims have this problem. Sharp edges coupled with hard anodizing appears to be
formula for spoke hole failures.

Bernice

 

[Carl Fogel]

Rapunzel <[email protected]> wrote in message news:<[email protected]>...
> In the process of rebuilding one of the CPX-30 rims, I discovered that the sharp edges around the
> spoke hole is a stress riser that caused a crack to develop around the spoke hole rendering this
> rim unsafe to use.
>
> When I looked at my other CXP-30 rims, I noticed the same manufacturing problem. Out came the file
> and I removed all the sharp edges from the spoke holes before building the wheel. This should stop
> the possibility of stress cracks due to the sharp edges.
>
> Most mechanical part drawings are noted with, "Break All Sharp Edges." for this reason.
>
> I wonder if other rims have this problem. Sharp edges coupled with hard anodizing appears to be
> formula for spoke hole failures.
>
> Bernice

Dear Bernice,

If you do this often, a hand deburring tool might be much faster and easier than filing. Here's
an example:

http://www.use-enco.com/CGI/INSRIT?PMAKA=380-1500&PMPXNO=943956&PARTPG=INLMK3

The tiny curved blades rotate freely in the large handle. With a twist of the wrist, the blade
scrapes the entire circumference of a small hole. More twists scrape the right-angle shoulder into
an even more rounded profile.

If it doesn't work on a rim for some reason, you're only out about $10 for this example. Most tool
stores will have equally inexpensive models.

Beats reaching for a tapered reamer and then deciding that it's not quite the right tool.

Carl Fogel