Re: Vacuum forming 7K interface "covers"


Chuck Harris <cfharris@...>
 

My saying "*About* 1 inch by 3 inch" indicates that it was just a
guesstimate.

I was giving an approximate size to eliminate any of the other parts,
particularly any "prismatic" parts, from the mix.

Since my mind's eyeball approximation isn't good enough:

Measured with my caliper, I read: 3.855" x 0.764"

It is injection molded, evidenced by mold fill marks, and a swirl
in the plastic composition where the flows occurred. It has 8
sprues, arranged in a rectangular matrix.

The plastic is white, translucent, and slippery, probably one of the
polyethylene types of plastic. The plastic is slightly unstable, as
it started to warp within minutes after my removing it from the
connector.

I don't want to burn it for further classification of the plastic,
as the part is still serviceable.

The cross sectional shape is complex in that it has special "hooks"
that retain the part. It is loosely in a class called a "C" channel.

It is not something that will be easy to make with a 3D printer of
the hobby class, as it is only 29.5 thousandths of an inch thick,
with some features that are less than 5 thousandths.

It is in the shape of an extruded solid, so extrusion would be a good,
though expensive, way of making this part, if you use the right
plastic.

The manufacturer (presumably Tektronix) obviously thought injection
molding was much cheaper and easier, and probably used manufacturing
equipment they already had on hand... Plus, it eliminates a special
machining operation to cut the pieces to length.

-Chuck Harris

Colin Herbert via groups.io wrote:

I thought that I knew what you were talking about until you gave the size as 1 inch by 3 inches. I am now flummoxed, because that isn't the size of the plastic parts that keep the (gold-plated) contacts in place in the backplane connector. Any chance of a photo or two?
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris
Sent: 22 April 2020 01:33
To: TekScopes@groups.io
Subject: Re: [TekScopes] Vacuum forming 7K interface "covers"

They are little plastic covers, very thin, and about 1 inch by
3 inches. Their purpose is to restrain the free ends of the gold
socket pins.

They are simply a thin sheet of plastic that is bent to a specific
shape, probably with a vacuum forming method.

They are prone to getting longitudinal cracks, and when that
happens, they fall out, or simply stop retaining the socket
pins. Often the pins will get crumpled by the plugin after this
happens. At a minimum, they won't make uniform contact on all
pins.

-Chuck Harris

Roy Thistle wrote:
On Tue, Apr 21, 2020 at 11:16 AM, Eric wrote:


The plastic covers for the “fingers”
Are those (on a 7603) the white (nylon?) prismatic objects above and below the gold contacts... looking down into the 7603 bay? ... or maybe just a Tek part number?
Best regards.
Roy









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