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"No-crimp" connector idea
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tautech:

--- Quote from: tooki on September 16, 2019, 03:40:12 am ---
--- Quote from: tautech on September 15, 2019, 08:15:44 am ---There's a simple trick for fine stranded cables and insertion into crimp lugs, ferrules and the like.

Pull off ~6"or more of insulation tape and spin/twist it loosely into a soft round rope shape and bind the strands not too firmly together starting from the insulation sheath nearly to the tip of the strands and then back towards the insulation a couple of turns. Keep finished end taught.
Insert exposed strand tip into lug and press not too firmly home.
The tape rope slides down the strands and will bunch up at the end of the sheath between it and the lug.
Unwrap tape rope then press cable fully home..... done !
Done properly you'll never miss inserting even a single strand.

This tape rope can be used again and again.

Thanks to my sparky mate Wayne for that one.  :)

--- End quote ---
Could you maybe make a video of this? I'm having trouble visualizing what you mean, but it sounds useful!

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Working with Wayne here tomorrow I think so I'll try to grab it with my phone.

Added the word twist for hopefully more clarity. ^^^
While it took a few minutes to write to get good meaning it takes but seconds to accomplish.  :)
ElectronicSupersonic:

--- Quote from: Gyro on September 15, 2019, 09:12:16 am ---Maybe I'm just not getting it, but I don't understand what stops individual strands from squeezing out into the open side of the 'omega' when compressed?  That would spoil the 'perfect fit'. Wire diameters will be subtly different between types too.
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Most multi-stranded wires are twisted, thus form sort of single core (especially when twisted some more, at least what's what I do before applying solder to the wire ends). Anyway in IDC connectors (say AVX Series 9176 http://datasheets.avx.com/StandardIDC_00-9176.pdf ) the slot for wire strands is open from one side (top) and strands going loose through that opening doesn't seem to be an issue. More other since the opening is omega shaped, the open part of it is somewhat narrower, thus to a degree should prevent strands from squeezing out. Another feature that could be done to enhance retention is an waist-like indentation perpendicular to the axis of a wire made in the middle of the contact "barrel".



As to wire diameter, connectors are usually rated to a specific AWG range. It can be designed to tight fit the particular range.


--- Quote from: Zero999 on September 15, 2019, 03:44:10 pm ---What voltage is this connector going to be working at?
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These would be (in theory) used for logic levels and/or 12V DC. Again these is basically just an idea - not something that is to be implemented in the form exactly as shown.


--- Quote from: ebastler on September 15, 2019, 07:59:55 pm ---How much spring travel do you expect those "omega contacts" to have? Your renderings look like the inner diameter of the eyelet which receives the wire is pretty much fixed. How would these contacts clamp wires of slightly varying diameter? (Or worse, multi-stranded wire twisted in slightly different ways, and with some room for the strands to move relative to each other?)

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Again, wire diameter somehow it's not an issue in IDC connectors. Say the above mentioned AVX Series 9176 are rated for a range of different AWGs (18-24 in this case). Also a dedicated groove to surround the eyelet can be made in the plastic shell, that would apply an additional pressure enhancing retention.
Simon:
You are missing the point. You can't accommodate precisely one wire size. The same gauge in different strands is different diameter. I use Raychem 44 wire a lot and it's always seems smaller than equivalent commercial wire (and is 30% more resistive but is not pure copper). So that won't fit.
T3sl4co1l:
A slitted/opened figure-eight shape is probably practical, being an extrusion of the IDC connector spring-and-knife structure.  Or put another way, take what you've drawn but open the metal (opposite the open side) into another loop, to grant more spring (compliance range).  Vary material thickness to get required clamping force.  Possibly it could be used on two or three different wire gauges, rather than exactly one size (stranded or solid only).

It'll still need a tool to force the spring apart or punch the wire in.

Tim
Simon:
The simple fact is that any connector contact/terminal has the wire forced onto it to reduce the resistance of the junction. Simply holding a wire in a sprung part is not enough. I use D38999 connectors, they are not cheap, but the exceed the power handling capability of a mains plug in the same space. But they are not cheap because the design is much more well refined.

Horses for courses, but this design is a rather poor horse. If you are interested in connector design there is the wurth book on the very subject: https://simonselectronics.co.uk/product/trilogy-of-connectors/
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