Does anyone know where to get 6P4C (RJ11) modular plugs for thick, round cable?

[MaximRecoil]

I have some round cable that's 0.175" diameter that I want to use as a modular line cord. I put some RJ11 plugs on it a long time ago, ones that were supposed to be for round cable, but the opening was too small to get the cable into it far enough to get a good strain-relief crimp on the outer insulation, so it pulled out of the crimp (see attachment). The cord still works but I'd rather have some plugs that fit right.

I know that they must exist because CAT5 cables with RJ11 connectors exist, and CAT5 cable is thicker than the cable I'm using (it's about 0.2" diameter), for example:

https://www.ebay.com/itm/332636896178

[poplar1]

I don't know about round vs. rectangular opening in the plug. However, the most common plugs are intended for stranded wire only. There are different plugs for solid wire.

[MaximRecoil]

Yeah, they make them for round and flat cable, and for solid and stranded wire. In some cases, the same connector is claimed by the manufacturer to be suitable for both solid and stranded wire. They never seem to say how thick of a cable they will accommodate though.

However, I think I found something. I asked someone on YouTube who made a tutorial video about making an RJ11-to-RJ45 cable, using CAT5, what specific RJ11 connector he used, and he said he used these:

https://www.idealind.com/us/en/shop/product-type/datacomm/85-344.html

You can see that CAT5 cable is used in the picture, and it says in the description:

6 position, 4 contact RJ-11 modular plug for Cat 3/5e and traditional phone wire

It also says they work with both solid or stranded wire:

Three prong contact design for use with solid or stranded 24-26 AWG insulated copper conductors

So I'll probably give those a try.

[TelePlay]

Isn't the cord restraint in all of these connectors the pins piercing the conductors.

I've never seen a modular plug which grips the cord exterior sheathing itself.

The way flat line modular cord is made all conductors have a "grip" on the exterior sheathing.

In your "failed" image, I see the tubular sheathing covering the conductors sliding back, out of the plug, while the conductors remain in place.

That sheathing, being plastic or cloth will slide both ways on the conductors. I don't know what modular cloth cord manufacturers do to keep the sheath inside the plug but superglue comes to mind as someone that will work.

Somewhere sometime ago I seem to remember modular plugs with larger openings to accommodate larger, than flat line, cloth cordage. And, yes, there is a difference between stranded and solid conductor modular plugs.

This topic reply shows the difference but the entire topic is quite informative.

http://www.classicrotaryphones.com/forum/index.php?topic=16074.msg166793#msg166793

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I have seen that type of sheathing sliding backward pn the power cord used to charge my iPhone, fixed with superglue after sliding it back into the plug.

[RDPipes]

I don't know mine all have a pinch point restraints on them.
You might want to look closer at your connectors.
Please excuse the blurriness these were taken quick.

[MaximRecoil]

Isn't the cord restraint in all of these connectors the pins piercing the conductors.

I've never seen a modular plug which grips the cord exterior sheathing itself.

They all have a strain-relief part that grips the exterior insulation, all of them that I've ever seen anyway. If you look at the underside of an RJ11 plug that's already been attached to a cable, you will see a depressed rectangular area. That part in there isn't depressed before crimping; it gets pushed down in to grip the cable when you crimp. One of the pictures in the eBay auction I linked to shows a good view of it (see attachment). See how the end of the green cable is being pressed/pinched down hard, enough to deform the cable? That cable never would have fit in there in the first place if the strain-relief crimp piece had already been pushed down before crimping.

In your "failed" image, I see the tubular sheathing covering the conductors sliding back, out of the plug, while the conductors remain in place.

Yeah, like I said, it still works fine because the conductors are still crimped by the contacts; it's just the strain-relief crimp that failed. On the other end of that same cable, the strain-relief crimp is still holding on, but just barely.

[TelePlay]

You're right.

The crimper has a bar that pushes down on a preset plastic flange the holds the flat line cord in place.

I just burned a connector, crimped it without a wire in it.

Was able to reset the plastic flange with a flat bladed screw driver and a hammer.

Put a cut off piece of flat line, inserted it and crimped it again. The cord was securely held in place (the end was cut off, not stripped off of the conductors.

After putting hundreds of these on flat line cordage, learned something new, thanks!

Now, back on topic, OldPhoneWorks makes cloth cords with modular connectors. Don't know how they do it or what they use but I have some and the modular cordage is somehow restrained in the modular plug.

[TelePlay]

I can see how flat line cord, which has no give between the sheathing and the conductors is better held by the flange restraint than a round plastic or cloth cord with a lot of space between the sheathing and the conductors.

Possibly filling a quarter inch of the end of the round cordage with something that sets up before crimping the connector would give the flange restraint something to "bite" on.

[MaximRecoil]

I can see how flat line cord, which has no give between the sheathing and the conductors is better held by the flange restraint than a round plastic or cloth cord with a lot of space between the sheathing and the conductors.

Possibly filling a quarter inch of the end of the round cordage with something that sets up before crimping the connector would give the flange restraint something to "bite" on.

In my case, the opening in the back of the RJ11 connectors I used was just too small for the 0.175" diameter cable. No matter how hard I tried to force it in there, I could only get a little bit in so the strain-relief crimp thing could only grip the very end of the insulation, which didn't last for long, at least not on the end that was plugged into the phone. The other end, which was plugged into the wall jack, is still holding on (barely), but that's because it doesn't get moved around like the end plugged into a desk phone does.

With a larger opening so that the outer insulation can slide in as far as it's supposed to, the strain-relief crimp should hold, just as it does with RJ45 connectors, which are nearly always crimped to round cables (such as CAT5). They have the same type of strain-relief crimp mechanism that RJ11 connectors have.

The ones I linked to in post #2 claim they are for use with CAT3 and CAT5, so they should have a big enough opening in the back for my cable, which is about the same diameter as CAT3 (in fact, I think it actually is CAT3 cable).

[TelePlay]

While looking for proper connectors, have you considered using a Dremel tool with a suitable cutting bit to mill out some of the plastic on the side opposite the flange retainer so your cordage would fit all the way in?

The other thought would be to compress the cordage end in a vise to make it more like a flat line cord and quickly move it from vise to plug and crimp before the compressed part begins to expand?

[MaximRecoil]

While looking for proper connectors, have you considered using a Dremel tool with a suitable cutting bit to mill out some of the plastic on the side opposite the flange retainer so your cordage would fit all the way in?

That might work, but I didn't have a Dremel when I made that cord, which was quite a few years ago. And now I don't think I have any more new connectors to try; I can't remember how many I originally bought, and if I bought more than two, I have no idea where they are anyway. I need to buy new connectors either way, so I think I'm going to try those Ideal 85-344 ones, which hopefully will work properly as-is.

The other thought would be to compress the cordage end in a vise to make it more like a flat line cord and quickly move it from vise to plug and crimp before the compressed part begins to expand?

Yeah, that might work too. Could even give it a little heat from a heat gun to thermoset it into a flatter cross-section with a vise. Those are both things to keep in mind if the ones I buy don't work well as-is.

[TelePlay]

OD reduction also worked.

I have some 3/16" 5 conductor rubber cord the I shaved a 1/4" length on the end down to a volume that would fit into a RJ11 modular plug.

Not the best images but the cord is securely restrained. I tugged on it but it did not come out.

I used the plug I burned above so no conductors from cord end to pins.

Doesn't look the best (my first OD reduction attempt) but with a bit of practice and finding the right "grinding" tool and/or setup, the attachment would look seamless.

[TelePlay]

It's really a question of volume. The cordage, conductors plus sheathing, cross section has to be just a bit less than the opening in the modular connector.

There are four ways to get the connector to restrain the cordage: 1) fill the end of the  sheathing with a solid setting material if the sheathing is loose around the conductors; 2) increase the opening in the connector with a file or Dremel tool to a bit more than the OD cross section of the cordage; 3) trim the cordage sheathing to an OD that just fits into the connector opening; or 4) a combination of #2 and #3.

I found some NOS RJ11 round cord modular conductors on eBay and will post a comparison of them here when they arrive.
 

[MaximRecoil]

I found some NOS RJ11 round cord modular conductors on eBay and will post a comparison of them here when they arrive.

The ones I used were for round cable too, but even among ones for round cable, there must be differences in the size of the openings, since some of them can accommodate CAT5 cable, which is significantly thicker than the cable I used (0.2" vs. 0.175").

I've attached a picture of the other end of my cable. You can see that the strain-relief crimp doesn't have a good grip on the insulation at all, because I was only able to insert it into the opening about halfway. Had I tried to use CAT5 with those particular RJ11 connectors, I wouldn't have even been able get it started into the opening as-is, so there has to be a drastic difference in the size of the opening compared to the ones that can accept CAT5 cable.

I just checked my emails and found the Digi-Key invoice; these are the ones I ordered about 4 years ago:

https://www.digikey.com/en/products/detail/assmann-wsw-components/A-MO-6-4-SR/930265

As you can see, it says they are for round cable. Also, it shows I ordered 10 of them, but I have no idea where the other 8 are now.

[TelePlay]

It's really a question of volume. The cordage, conductors plus sheathing, cross section has to be just a bit less than the opening in the modular connector.  . . .  I found some NOS RJ11 round cord modular conductors on eBay and will post a comparison of them here when they arrive.

The NOS round cord modular RJ11 plugs arrived today.

There is a difference. The image below shows both a larger width and height for the round cord connectors vs. the flat line RJ11. Even the RJ45 has a rounded side to accommodate round cordage.

It a cross section area issue. If the cordage cross section is larger than the plug opening, it won't fit and either the connector and/or cord will have to be adjusted.