make your own I/O cables

We used to make those all the time. The ribbon cable has a colored strand so you don't turn the cable over by chance and get the connector reversed.

Just cut to length and use a 1 ton arbor press with a foot that is at least as long as the connector and press the connector through the cable and into the cover. Cover will snap in place.

I think I could even do it!

Paul

g deal. =A0!!!!

You can plug two ribbon cables into a section of wirewrap header to join them. That will cross the odd and even rows, but a second header and cable will cross them back again.

If you get the 3M connectors watch out for a flange meant to stop the cut end of the cable.

When I don't have a press or smooth-jawed vise available I push the ribbon cable onto the split pins with my thumbnails. That also works well when I have to separate the wires and rearrange them, such as to swap the even and odd rows.

jsw

Header connectors on .1" * .1".

That changes the wiring pattern, though. The odd row becomes the even row (and vice versa), if you don't use a pair of them and a short cable to make a double transition. I had to do that in some test fixtures I built, to allow for fast repairs on the test bench.

Interesting -- flat cable bundled up into a round jacket. That is convenient.

But you may (or may not) want/need to terminate the shield shown in the details of the cable. It will not normally connect to any pins in the connector.

O.K. That one has a single bar on the back to force the wires over the pins, which are typically a two-petaled tulip which penetrates the insulation on either side of the pin, and then cuts in to make contact with the wires.

There are usually optional secondary bars to handle the stress if you unplug and re-plug frequently.

Anyway:

1) Get a few spare connectors.

2) Be careful that the connector is truly at right angles to the cable. If at an angle, the spacing of the pins won't match the spacing of the wires, and you will wind up with adjacent wires shorted by the pins where they punch through.

3) You can squeeze the connector onto the cable using a good vise with parallel jaws. Some styles need notches in the pusher bar to clear pins which guide and lock the strain relief (e.g. T&B Ansley blue-ribbon style (commonly mis-called Centronics style) connectors.

And ideally, you have a lever which moves the pusher bar down to a specific height, and the connector body in a guide holding it at the right height for the pusher bar.

4) Be sure to get the same edge of the cable (either a different color stripe, or a brown wire (for multiples of ten wires, start on brown, end on black) lined up with the marked pin-1 end of the connector (usually a triangle on one side) so the same wire becomes pin 1 on each side. If that happens, the rest are all correct.

If you have a lot of these to do -- mill a slot in a block of aluminum just the right width to hold the connector upright -- and with a second milled slot just wide enough to accept the keying bump in the center of the connector. Make the depth of the slot just right (and the thickness of the aluminum block too) so the dimension from the bottom of the block to the top of a fully crimped connector is 1.000", and set up something like a small arbor press with a cross bar to close down to

1.000" height. (Perhaps have the bar longer than the connector-support block, with 1.000" high blocks on either side to stop the stroke of the pusher bar.

If you are making it only for a single width of connector (e.g. your 50 pin ones), mill an extra thickness to at least one side of the ribbon to hold it lined up while you crimp. Otherwise, make and adjustable bar for the guide function.

And -- it would be helpful to have another bar for the press, which carries a steel blade to cut across the full width of the ribbon cable in one cut. This makes it easier to get things started into the connector and lined up square. I've actually got two presses from hamfests. One (the cheaper one) I keep set up with the blade only. The other (a T&B Ansley press) I have a full set of pusher bars (notched and not as needed) and a full set of blocks to support the connectors at the right height. The Blue-ribbon style, and the DB-25, DD-50, DE-9 DA-15, require the notched pusher bar. And -- the connector goes fully through the support (which is a U-shaped slot milled in it) and rests on the bottom, so it uses the full 1" height -- plus the clearance in the notched pusher bar.

The pusher has an adjustment stop, which when set at '0', closes to 1.000" precisely. At other settings it is a bit higher, corresponding to the needs of the connector in question.

The reason for the height and support is so the connector is not crushed by the press. If using a vise -- be very careful to not over-do it.

Good Luck, DoN.

They are made -- but designed to mount to panels.

Or male connectors are for printed circuit board mounting.

I used to be able to find the male bulkhead connectors, but it has been a long time since I last looked for them. I used to find them at hamfests for somewhat improved prices.

Digikey is perhaps not the place to look for that one. Try also Newark, Allied, and Mouser.

"Male IDC connectors".

BTW There also is shielded flat cable -- with rather tough jackets.

Good luck, DoN.

ROFLMAO!!!

I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)

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

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.

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.

Stan

Both links "bounced"

cable

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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.

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.

Agreed!

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.

The ribbon cables cannot be folded in half lengthwise without having internal wire breakage. I have fixed more than a couple CNC controls with intermittent problems by changing out the ribbon cables that were improperly installed. The cables were run to a swing out sub panel and folded in half which stressed the wires on the fold as the panel moved. The cable should be kept flat and when making a bend fold it across the cable to make the corner bend.

John

When Junior was prettying up his computer with custom made cables, I came up with two lexan plates hinged together with separable hinges complete with squaring guide lines so that he could get everything lined up to perfection then give it a good squeeze with large channel lock pliers. Gerry :-)} London, Canada

Don't count on that, but good luck!

Yea, I've been surfing digikey for over 1/2 hour and can't find one. maybe i don't know what to call it.

Karl

REPLY:

3M made a lot of the connectors.

Most of the males available will be for PC board mounting. Look at a SCSI drive sometime. What you want, if you can't get an IDC, is a "gender changer". I've had a couple from scrounging surplus, so they are/were available. Likely priced way above the IDC connector price unless you scrounge as well as I did. You need a PC-centric dealer, Digi-Key doesn't have everything, as thick as their paper catalog is. Unfortunately, my favorite surplus haunts are long gone. Weird Stuff Warehouse is still around, if not in the original locale. Or you could design your own gender changer with two males mounted to a short piece of suitably etched PC board. Have seen that done with other sizes of ribbons.

Stan

Most of the males available will be for PC board mounting. Look at a SCSI drive sometime. What you want, if you can't get an IDC, is a "gender changer". I've had a couple from scrounging surplus, so they are/were available. Likely priced way above the IDC connector price unless you scrounge as well as I did. You need a PC-centric dealer, Digi-Key doesn't have everything, as thick as their paper catalog is. Unfortunately, my favorite surplus haunts are long gone. Weird Stuff Warehouse is still around, if not in the original locale. Or you could design your own gender changer with two males mounted to a short piece of suitably etched PC board. Have seen that done with other sizes of ribbons.

Stan

Was just thinking of Weird Stuff about 2 hours ago. Daughter was looking for chalk board for the 2 year old. Figured WS would have something like that. It was originally a block over from my office in Milpitas. Handy in those early 1980 days.

I've made emergency male ribbon connectors from female ones and wirewrap headers, but their reliability depends highly on your manual skill level.

Separate the wires into pairs for an inch or two. Clamp the connector in a vise with the split forks barely above the jaws. I fill in the wire/socket 1 triangle with a fine tipped marker or nail polish so I can still locate it Give pair 1 and 2 a half twist. Using two fine screwdrivers or your thumbnails, press wire 2 onto the end fork (socket 1) and red 1 onto the adjacent socket 2 fork. This swaps the odd and even numbered rows. Repeat for the rest of the wire pairs. Be careful to keep the lengths even or the cable will be too sensitive to strain. Definitely add a strain relief bar. Plug in a double row wirewrap header and lash it in place with thread.

When you plug this into a standard ribbon cable the two even/odd crossings cancel.

To quickly check the cable for continuity, make test plugs for the ends from double row headers. On one end attach a lead to pins 1 and 50, then wirewrap 2 to 3, 4 to

5, etc. For the other one wrap 1 to 2, 3 to 4, etc. Bare wire is fine. Plug in both headers and buzz between the 1 and 50 leads. If they are open, search down the row.

Good luck with this. It's worked well for me but not so well for anyone I've showed it to, usually the head of the assembly/rework department. I was the designated stuckee to negotiate between them and engineering.

jsw