Thanks to all for your help. On further inspection of the CDROM case
it does appear that the "tube" was extruded using a punch or punch/die
combo of sorts. Will follow up on Machineman's suggestions. Probably
try a thread-cutting tap after punching since I have it already. Can
always get a thread-forming tap if the extruded metal is too thin.
Hopefully, the extra torque required for forming won't cause fatigue
if the metal is too thin.
> And the threads are probably formed instead of being cut. I havn't
> tried form taps in this method but they will most likely work. Find the
> tap drill size for it, and make a tapered punch to suit, and a die with
> rounded corners to give you the lead >
> > > >
> >> Hi,
> >>
> >> I notice that the cases for CDROM drives etc. used in PCs are
> >> constructed of relatively thin sheet metal (1/32" perhaps) yet are
> >> able to support M3x.5 machine screws. The hole for the screw has what
> >> looks like a 1/16" - 1/8" long threaded tube on the inside of the case
> >> that basically supports most of the screw threads. Is this done with a
> >> special tool or is this "tube" brazed over the hole then tapped?
> >> Normally, if one uses a sharp drill bit then taps anything 1/32" thin
> >> there is very little thread to support a machine screw regardless of > >> the TPI.
> >
> >
> > Looking at a spare CD drive, I see it's not seperate pieces for the
> > threaded holes. The thin (18 gage, I think) metal is made thicker at the
> > hole by swaging it--punching a die into it to form a lip, which gives
> > enough for a couple threads.
> >
> > Ken Grunke
> > SW Wisconsin
> >
formatting link
>
> >
> >
> >