On 2010-10-22, wrote:
On Oct 21, 2:49*pm, Karl Townsend
wrote:
I need to make up cables with 50 pin ends, two rows of 25 on .1
spacing. I've never done this. Are the parts below all I need? Any
instruction on putting the IDC end on?

50 conductor cablehttp://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&N...

IDC sockethttp://www.alliedelec.com/search/productdetail.aspx?SKU=5182308

Karl

I used to make these up customized for my SCSI cabinets. In SCSI
service, every other wire is a ground, so the ribbbon cable is
shielded that way rather than with wonking big braided covers. You
can also get higher speed stuff that has pairs twisted every few
inches in the flat stuff, usually narrower than the 50 wire ribbons,
though.

I've got some twisted pair ribbons at 60 pin width -- with a
breakout to straight every 12" for crimping an IDC connector on IIRC.

I have run across really old ribbons that had external
shielding, very heavy stuff and would be hard to squeeze IDCs onto.

You could not squeeze an IDC onto those -- if you mean the black
jacketed ones. But you could strip the jacket, and then roll back the
shielding screening and make external connections from those to ground,
while you crimped an IDC onto the then exposed ribbon cable.

You can get bulkhead connectors for Centronics, I wouldn't consider
those for a shop environment. Usual practice on the big computer
systems was to run ribbon up to the bulkhead, then go with a D-
connector externally with round rubber-covered and shielded twisted
pair cable, either soldered or crimped to the connectors. Had a lot
better abrasion resistance when dragging it under the flooring.

Agreed!

I had a plastic gizmo for squeezing IDCs, was just a nest for for the
front part and a guided plate for the rear. Could be used in a small
arbor press or a smooth-jawed vise. Important to get the ribbon
square with the connector before squeezing, one edge of the ribbon
will be striped, this matches up with an arrow molded someplace on the
end of the connector or number "1". Go easy on the pressure, it
doesn't take a lot and some makes of connectors can fracture if over-
squeezed. Then you get to slice off the dud and start over. You can
get strain reliefs and ribbon for same for pulling the connector,
highly recommended if you ever expect to get back into the thing at
any time.

One of the hobby makers, Vector I think, made a set of presser
bars and nests which could be used either in a vise, or in their wimpy
(sub 1-ton) arbor press. They also had special presser bars which could
be used to put a single row of wire-wrap pins into a perfboard at at
time. These held the square pins all parallel to the axis, so two rows
of them would fit an IDC connector.

Looks as though they have gone to much more expensive ways to do
things now. :-)

Enjoy,
DoN.

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