[Antennas] Hamwhip

2003年1月19日 13:14:40 -0600

----- Original Message -----
From: "George Tonsmeire" <[email protected]>
>> Hi - I just bought 2 20 meter Hamwhip antennas at a hamfest yestrday and the set screws that hold the stainless steel rod
in the ferrule will not screw in enough to screw down on the whip and hold it - I guess the ferrule is not tapped far enough
and the set screws bottom out before they contact the whip - I would appreciate any suggestions on how to fix this or how to
contact the manufacturer - no address on antenna or papers - I understand that they are in Miami, FL - I think the thing to
do is to try to tap the hole, but do I need to drill out the existing hole or just force the tap through what uis there now?
The hole seems to go all the way through but the screw stopps before contacting the whip - I can't force the set screw
through the existing hold - I think it just needs to be able to screw all the way through - but even with the whip completely
removed the set screw stops before going all of the way through the ferrule - Any help appreciated <<
 Howdy... stainless steel is hard to work with, and my guess is just as you
stated, the guy who built the whips didn't tap down deep enough.
 One thing to consider, just take them to a machine shop. I suspect that
what happened was that the guy who built the whips was using just a
"taper" tap (and it was probably getting worn out, being used on a lot
of stainless steel). The machine shop needs to chase the threaded hole
with a bottoming tap. A taper tap, by far the most common tap sold,
is great for tapping holes in plate metal. BUT, in a confined space, such
as the bottom of a blind hole, or with very little space at the end of the
work, you can start the work with a tapered tap, go as far as you can,
then exchange the tap with a bottoming tap and go down to the end
of the hole.
 A quick way to tell -- a taper tap has a point, almost but not quite
like a normal high-speed drill bit, while a bottom tap looks a lot more
like a capscrew (with the hollow flutes to take out the cut thread bits).
 You COULD, but I don't recommend it, get another tap at a hardware
shop (4-40, 8-32, not sure what size you have) and carefully grind off
the point of the tap so that it's more of a blunt point, trying to keep it
as cool as possible so as not to take out too much temper, and use lots
of cutting oil and patience. You don't want to break the tap off in the
hole, in stainless it's almost impossible to recover from that. (sigh)
 I don't work in a machine shop any more, but for 5 years, that was
part of my job, cutting threads in deep, blind holes... and that was
a PITA if you didn't use lots of oil and sharp taps... but that is
another story! (grin)
 Good luck!
 _Ray_ KB�STN