Crimp Plug

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parkview
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Joined: Tue Jun 24, 2014 8:25 pm
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Crimp Plug

Post by parkview » Mon Jul 02, 2018 10:09 am

I am working on making a line of special crimp plugs that interface with a 4 pin SH style plug. This crimp plug is being designed to allow it to be crimped onto a 3 silicone covered wire strand. I wont go into the reason why here, so this blog topic will cover the projects progress.

So lets start off with a CAD view of how it might look:
Example-Plug_sml.jpg
Example-Plug_sml.jpg (60.68 KiB) Viewed 4839 times


The above three wires have an inner core of around .8mm and an OD of 2.3mm.

At the moment, I am exploring using some phosphor bronze prongs to skewer the wire sheath, and embed into the multi strand wire cores. These prongs and the 4 wire SH plug will be mounted onto a small PCB board:
Plug PCB - dimensions_sml.jpg
Plug PCB - dimensions_sml.jpg (133.37 KiB) Viewed 4839 times


and will maybe look something like this:
Example-Plug_PCB_piecers.3.jpg
Example-Plug_PCB_piecers.3.jpg (24.54 KiB) Viewed 4839 times

parkview
Guru Maker
Posts: 603
Joined: Tue Jun 24, 2014 8:25 pm
Location: Busselton
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Re: Crimp Plug

Post by parkview » Mon Jul 02, 2018 10:36 am

Initially I looked at how a RJ45 network crimp plug worked and I disassembled a few of them to extract the gold plated metal crimp teeth. I tried trimming them down to a smaller size, but that didn't work very well. After a chat with SW Maker member on some different production methods, I ordered some phosphor brinze sheet and while waiting for that to arrive, had a go at etching some crimp teeth out of brass.

I used Designspark Mechanical CAD package to quickly draw up a single 3mm tall x1.5mm wide crimp tooth and used Inkscape to replicate and add on a attachment frame:
laser etching model 6 - multi-12_sml.jpg
laser etching model 6 - multi-12_sml.jpg (25.98 KiB) Viewed 4838 times


I used a laser/paint masking system http://forum.swmakers.org/viewtopic.php?f=12&t=186 and etch 12 teeth out of 0.2mm thick brass:
finished etching brass. final strip_sml.jpg
finished etching brass. final strip_sml.jpg (77.73 KiB) Viewed 4838 times


Above, some of the teeth fell off while I cleaned off the black masking paint using acetone. Below, is just a production prototype and is not meant to be functional. To give you an idea of size, the PCB is 0.8mm thick and the PCB is quite a bit smaller than a 5 cent piece:
brass crimp plug.jpg
brass crimp plug.jpg (163.85 KiB) Viewed 4838 times

parkview
Guru Maker
Posts: 603
Joined: Tue Jun 24, 2014 8:25 pm
Location: Busselton
Contact:

Re: Crimp Plug

Post by parkview » Mon Jul 02, 2018 11:23 am

So, how does this all look like in real life? Below is are some 3D printed examples of the crimp housing. In reality, I think it will have to be a bit bigger, and a bit taller, as it has to house the 0.8mm thick PCB.

Two half's of the crimp plug - yes, the plug and wiring is keyed, so it can only go on in one direction:
crimp plug.black.2.sml.jpg
crimp plug.black.2.sml.jpg (44.97 KiB) Viewed 4838 times


and how it might look when it's crimped into place:
crimp plug.black.3.sml.jpg
crimp plug.black.3.sml.jpg (48.02 KiB) Viewed 4838 times

parkview
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Posts: 603
Joined: Tue Jun 24, 2014 8:25 pm
Location: Busselton
Contact:

Re: Crimp Plug

Post by parkview » Sun Jul 08, 2018 2:16 pm

Had a go at etching out some of the crimp teeth out of 0.2mm thick phosphor bronze sheet. Luckily I tried to etch out two plates of 24 teeth. After some five hours and late at night, I took a peek, and it looked like they where done, so I pulled one out and cleaned it up to find that it was nearly done. I left the other one in for an extra 45 minutes:

There was significant undercut and the masked teeth where placed too close together for the etchant to get in properly to the metal:
partial-bronze-teeth.3.sml.jpg
partial-bronze-teeth.3.sml.jpg (38.68 KiB) Viewed 4834 times


0.2mm thick doesn't sound like much, but it's kind of cool to see close up of the partial etch process:
partial-bronze-teeth.2.sml.jpg
partial-bronze-teeth.2.sml.jpg (41.41 KiB) Viewed 4834 times


It would be handy to be able to mask and etch both sides of the sheet, but I struggle to correctly register the mask during the laser process.

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