[ARC5] ARC-5 Screws

[Mike Hanz]

Brian's solution is absolutely correct, of course.  But it raises the 
question of how you can accurately guide a *very* flexible .078" drill 
to just touch the edge of the root diameter throughout the length of the 
thread.  I suggest a perhaps overboard method of doing so at 
http://aafradio.org/garajmahal/C-29.htm but the fundamental key is using 
a #1 center drill to establish the guide hole.  With practice you can 
get within a few thousandths of the center by eye without using the 
center scope shown, especially if you use a head mounted magnifier of 
some sort and view the center point from 90 degrees apart while 
positioning the workpiece.  I try not to use a tap unless all else 
fails...a sharp dental tool will most often allow you to tease the 
remaining thread spiral from the female thread without damaging it.  
Corrosion may make that difficult, however, as Brian alludes.  A tap may 
easily cut off center, at least in my experience.

On 3/10/2012 8:26 PM, Brian Clarke wrote:
> The standard engineering solution is to drill at the root diameter and then
> retap - the tap, if you're lucky, will drive out the remnant of the previous
> screw. Sometimes, I've been really lucky, where there is no corrosion, and
> high pressure air has cleared the remnant.
>
> On Sunday, March 11, 2012 12:13 PM, Neil, ZL1ANM asked:
>> I've had at least one case where a screw head has sheared off, leaving the
>> remnant of the screw still in the cover. How do you guys remove that
>> broken off piece without damage to the threads in the cover?