[TowerTalk] [BULK] - N-Connector & Belden 9913F7

[Steve Katz]

Hi George,

Funny you should say this.  I've tried it, myself, using a drill press, a
small metal bench vice and a 7/64" new drill bit, and failed miserably.
Despite the "pilot hole" that's there, the problems I found are:

-The tiniest wobble of the bit, and I mean tiny (not visible to the eye),
screws up the operation because you're drilling something that's only very
slightly larger in O.D. than the newly intended I.D.  

-The vice, or pliers, or almost anything, holding the solid pin "tip"
doesn't have enough grasping tension to hold the pin steady.

-Obviously, gripping the hollow part of the pin won't work, it has no
strength and collapses.

What I did, to cure the problems, is make a holding tool that is machined to
exactly the exterior dimensions and form of the original pin, and exactly as
deep.  This tool has a split core so the pin can be inserted, then clamped
by the tool which completely surrounds the pin.  Then, I use a CNC vertical
machining center with a .109" milling bit and run one pass into and out of
the pin.  Perfect results every time.

Problem is, if you don't have toolmaking capability or a CNC...

I'd say if you can do this with a drill press and pliers you must be pretty
good.  I tried it and ruined many pins before I gave up.

Since I found that somebody else already does this in large quantities, I
just buy the stuff from him now.  Not worth typing up a CNC to run pins that
I can buy for $1.50 each.

WB2WIK/6



-----Original Message-----
From: Dubovsky, George [mailto:George.Dubovsky at andrew.com]
Sent: Friday, September 23, 2005 11:09 AM
To: Steve Katz; Fred Mott; towertalk at contesting.com
Subject: RE: [TowerTalk] [BULK] - N-Connector & Belden 9913F7




Steve, Fred and the list,

No question, the special pins are the best way to go, but if I needed
one on a Saturday afternoon, I would not hesitate to drill one out. It
certainly does not require CNC machinery or any exotic tooling to
accomplish the task,  for one VERY important reason: the manufacturer
has already provided a pilot hole exactly where you need it, right on
the center line of the pin, and pre-drilled to the correct depth.

If you attempt to drill a slightly larger hole following a pilot hole,
the larger hole will be on the same central axis as the pilot, even if
you are performing the operation in a lathe and the pilot is off-center
of the lathe axis. The unequal cutting forces from an off-center drill
quickly steer it back to the pilot axis - this is absolutely true for
short holes and small diameter drills (like this discussion), and the
effect is still dominant for large drills and deep holes.

So how to do it in practice? A drill press and a small vise to hold the
pin from rotating would work every time. A drill press and holding the
pin against the drill press table with a small pair of pliers should
work darn near every time. Either the work will shift slightly, or the
drill will flex slightly, but the resulting hole WILL be in the center.
If you have a good trigger finger, you could likely use a variable speed
hand drill, a pair of non-marring pliers, and a dose of luck to drill
out the pin.

Another one of those things that's easier done than said...

73,

geo - n4ua

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Steve Katz
> Sent: Friday, September 23, 2005 1:20 PM
> To: 'Fred Mott'; towertalk at contesting.com
> Subject: Re: [TowerTalk] [BULK] - N-Connector & Belden 9913F7
> 
> Type Ns with special "hogged out" (milled out) center pins are readily
> available from a number of sources including The R.F. Connection in
MD,
> who
> almost always has them in stock for immediate shipment.  I just use
those.
> Tinning and filing the center conductor probably works, but is awfully
> labor-intensive.  "Drilling" a hole in the center pin isn't going to
work
> using conventional tooling -- this is a really critical process and
> requires
> a CNC machine and a fixture to clamp the pin.  The resulting milled
out
> pin
> has *very* thin walls, if you "miss" by a few thousandths of an inch,
> you'll
> break through the wall and have a pin headed for the trash can... -
> WB2WIK/6
> 
> -----Original Message-----
> From: Fred Mott [mailto:fredmottcpa at earthlink.net]
> Sent: Thursday, September 22, 2005 5:34 PM
> To: towertalk at contesting.com
> Subject: [BULK] - [TowerTalk] N-Connector & Belden 9913F7
> 
> 
> How do you install a N-Connector onto a Belden 9913F7 coax.  


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