[time-nuts] WG mounting h/w (2)

[Robert Atkinson]

I think you are a snip too soon. My original post said "If you have to use screws, at least align two diagonal holes with 5/32" dowels while nipping up the  first two screws". Taper pins are also OK of the taper is slight and flanges are not too thick. Don't tighten the first two screws too tight at first to aviod warping the flange. In aircraft installations I've designed have used shoulder screws because they were specified by the equipment manufacturer.
 
Robert G8RPI.


--- On Mon, 20/9/10, Kit Scally <kScally at BYTECAN.com.au> wrote:


From: Kit Scally <kScally at BYTECAN.com.au>
Subject: [time-nuts] WG mounting h/w (2)
To: "time-nuts at febo.com" <time-nuts at febo.com>
Date: Monday, 20 September, 2010, 9:19



Hi,


Well, still not strictly, strictly true !  
In Ku & K  band earth stations I've worked in, I've never seen shoulder screws used, although the equipment used was mainnly from the USA.  
Next to you precision adaptors, SMA torque wrenches etc in your personal goodie box are sets of tapered pins, about 35-40mm long - that fit various diameter WG mounting holes (the old metric vvs Imperial issue again).

You insert a pair of pins on diagonal corners then add bog-standard SS hardware to the opposite diagonals & tighten.  The tapered pins are then removed and replaced with another pair of screws/nuts.  This ensures absolute (?) internal WG slot alignment.  There are a few variations on this theme if you must have absolutely minimum RL within that section of guide or if one guide face is threaded.  Hex-headed bolts are usually used.

That may explain why shouldered bolts are seldom seen.

Tapered WG pins fall into the 99.9999% unobtainium class of materials.


Kit
VK2LL

------------------------------

Message: 6
Date: Sun, 19 Sep 2010 10:15:17 +0000 (GMT)
From: Robert Atkinson <robert8rpi at yahoo.co.uk>
Subject: Re: [time-nuts] Semi-OT: Hardware for WR-90 waveguide
    sections?
To: Discussion of precise time and frequency measurement
    <time-nuts at febo.com>
Message-ID: <414785.76181.qm at web27102.mail.ukl.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Hi,
Not strictly true. Material is not important apart from environmental (corrosion) issues, but that is not the only concern. WG-16 (British) / WR 90 flanges are not dowelled. They rely on the fastners for alignment. The correct fastners are 5/32" shoulder screws (0.1557" dia 6-32 thread).
>>snip
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