[Shop-talk] retapping a hole

[Eric Russell]

I think tapping over the existing 1/4-28 will result in weak threads. How
about a Heli-Coil in 1/4-20?

EjR

On Sun, Jan 15, 2023 at 10:46 AM john <jniolon at att.net> wrote:

> I have a mirror mount on my truck door that held a rear view mirror.
> Unfortunately the mirror decided it didn't want to stay with my truck.
> So, I'm looking for a replacement. The mount is drilled and tapped for
> 1/4"-28 threads and most of what I find is 1/4-20.  I'm wondering if I can
> re-tap the metal over existing threads with a 1/4-20 thread and it will
> hold...or will I just make a mess of it and make it broke. The drill side
> for the
> two thread sizes are within a 64th or so of being the same and the mount
> is 7/16" or so wide so I have some meat to play with...
>
> suggestions?
>
> john
>
>
>
> another option... drill completely thru mount and find a mirror with a
> stud long enough to pass thru completely
> and secure with an acorn nut (or something)  at the back side of the mount
>
>
> another caveat... I don't want to remove the mounts from the door...
> involves removing windows and regulators
> to get to the internal nuts.
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-- 
Eric Russell
Mebane, NC
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