Loose Crimp Sleeve (Outer Ferrule) on BNC Ferrule after Crimping [RG-58]

[rstor22]

I found that the BNC center pin once inserted into a BNC connector clicks and locks in place and does not come out (for some RG-58 connectors). After crimping the center pin and the outer ferrule (crimp sleeve) and pulling to test the crimp everything seemed fine. On some of the crimps I have made I found that the outer ferrule did not crimp securely and pulling to test the BNC connection gave a false sense of security as it appears that the crimped center pin prevented the BNC connector from detaching from the cable (since the center pin is also crimped to the core of the cable).

I decided to do some more tests and crimped some outer ferrules (using an Xcelite ratcheting crimper) on the BNC connector (with no RG-58 cable / pin) and found that for some BNC connectors the outer ferrule just slides off after pulling slightly. I tried some unknown brands along with named brand Amphenol BNC with disappointing results. I found that I needed to adjust the tension dial to a higher tension on my crimp tool for the unknown brand BNC connector outer ferrule to crimp satisfactory to the BNC connector (though it needed A LOT of force for the ratcheting mechanism to disengage at that setting). Some other brands such as Provo BNC connectors had their outer ferrule crimped successfully at the lowest tension setting and seemed to be sturdy when pull testing by hand.

Today I had a colleague of mine who crimps RG-59 connectors on coax show me some of the cables he made. The finished crimped connectors on the coax appeared to be secure when pulling by hand. I then suggested to crimp an outer ferrule to a RG-59 BNC connector with no coax / pin. After crimping we found that the outer ferrule came right off the BNC connector very easily.

Has anyone test crimped a ferrule directly on a BNC connector with no RG-58 cable / center pin and does the ferrule appear to be crimped securely when test pulling by hand? I am assuming that even with no coax it is supposed to be a secure crimp that should not easily pull off, correct? Has anyone needed to adjust the tension setting (if available) on their tool for the outer ferrule to crimp correctly on RG-58 BNCs?

reference picture of what I mean by outer ferrule (crimp sleeve) : http://www.l-com.com/images/Coax_with_callouts.gif

[xavier60]

I had that problem with cheap RG58 crimp BNC connectors I got on ebay. The  ferrule walls were too thin.
I got firm crimps with replacement  ferrules with correct wall thickness from another seller. 
https://www.ebay.com.au/itm/Crimp-Sleeve-Ferrule-Pleated-Tube-Pipe-For-RG58-400-RG142-LMR195-Connector/152692980958?hash=item238d35fcde:m:m1lUxkQNOvO4gNYs8VbhBOg:rk:1:pf:0

[rstor22]

I had that problem with cheap RG58 crimp BNC connectors I got on ebay. The  ferrule walls were too thin.
I got firm crimps with replacement  ferrules with correct wall thickness from another seller. 
https://www.ebay.com.au/itm/Crimp-Sleeve-Ferrule-Pleated-Tube-Pipe-For-RG58-400-RG142-LMR195-Connector/152692980958?hash=item238d35fcde:m:m1lUxkQNOvO4gNYs8VbhBOg:rk:1:pf:0

I had made some rough measurements/calculations of the BNC ferrules / outer ferrules that I tested. At first I thought it was the result of the difference between the outer ferrule ID and the BNC ferrule OD which was the issue (i.e. the smaller the gap the better the crimp?). This didn't seem to be the sole reason as the one that crimped the best had a 1.07mm difference where two others that did not crimp well had a smaller difference. I think it may be a combination of the above difference along with the OD of the outer ferrule as the one that crimped the best had largest OD (6.54mm) of the outer ferrule when compared to the others (6.31, 6.33, and 6.47mm). I think the thickness of the outer ferrule as you mentioned also plays a part in this.

Can you advise of the OD of the replacement ferrules that you purchased? (the link only specifies the ID).

Thank you.

[xavier60]

Yes,
Original, OD 6.0 mm, thickness 0.2 mm
Replacement, OD  6.5 mm, thickness 0.5 mm

[vk6zgo]

I found that the BNC center pin once inserted into a BNC connector clicks and locks in place and does not come out (for some RG-58 connectors). After crimping the center pin and the outer ferrule (crimp sleeve) and pulling to test the crimp everything seemed fine. On some of the crimps I have made I found that the outer ferrule did not crimp securely and pulling to test the BNC connection gave a false sense of security as it appears that the crimped center pin prevented the BNC connector from detaching from the cable (since the center pin is also crimped to the core of the cable).

I decided to do some more tests and crimped some outer ferrules (using an Xcelite ratcheting crimper) on the BNC connector (with no RG-58 cable / pin) and found that for some BNC connectors the outer ferrule just slides off after pulling slightly. I tried some unknown brands along with named brand Amphenol BNC with disappointing results. I found that I needed to adjust the tension dial to a higher tension on my crimp tool for the unknown brand BNC connector outer ferrule to crimp satisfactory to the BNC connector (though it needed A LOT of force for the ratcheting mechanism to disengage at that setting). Some other brands such as Provo BNC connectors had their outer ferrule crimped successfully at the lowest tension setting and seemed to be sturdy when pull testing by hand.

Today I had a colleague of mine who crimps RG-59 connectors on coax show me some of the cables he made. The finished crimped connectors on the coax appeared to be secure when pulling by hand. I then suggested to crimp an outer ferrule to a RG-59 BNC connector with no coax / pin. After crimping we found that the outer ferrule came right off the BNC connector very easily.

Has anyone test crimped a ferrule directly on a BNC connector with no RG-58 cable / center pin and does the ferrule appear to be crimped securely when test pulling by hand? I am assuming that even with no coax it is supposed to be a secure crimp that should not easily pull off, correct? Has anyone needed to adjust the tension setting (if available) on their tool for the outer ferrule to crimp correctly on RG-58 BNCs?

reference picture of what I mean by outer ferrule (crimp sleeve) : http://www.l-com.com/images/Coax_with_callouts.gif

The thickness of the braid is important in determining how tight the ferrule will be.
I have never tried just crimping the ferrule without the braid, but I would expect it to not be as secure as using it in the correct manner.

[SeanB]

When I was making terminators for networking the simple solution was to fold the outside lead of the 100R resistor over qand wind it around the outside till it was finished, then slip the ferrule over and crimp it. With those that you have loose crimps simply cut the braid longer and then push it back, and after putting the centre pin in push the braid down, fold over and flatten back against itself then pop the ferrule over.  Can be poor connectors, cable with thin braiding but the fix, other than tossing out for the right stuff, is just to do that.

Yes I buy generic BNC fittings, and generic cable if nothing else is available, and do not want to wait the weeks it will otherwise take to arrive, or pay the price for RS to deliver one connector "available within 6-10 business days from the UK/EU warehouse" via courier.

[rstor22]

Yes,
Original, OD 6.0 mm, thickness 0.2 mm
Replacement, OD  6.5 mm, thickness 0.5 mm

These dimensions look like it may work for me, I've asked the seller to see if they will allow shipping to Canada. Thank you!

The thickness of the braid is important in determining how tight the ferrule will be.
I have never tried just crimping the ferrule without the braid, but I would expect it to not be as secure as using it in the correct manner.

I guess the braid would also fill the space and would contribute to a tight crimp though with no braid I would think the outer ferrule shouldn't just slip off with so little force. It makes me question the quality of the crimp with the braid in place and the contact between it and the BNC...

With those that you have loose crimps simply cut the braid longer and then push it back, and after putting the centre pin in push the braid down, fold over and flatten back against itself then pop the ferrule over.  Can be poor connectors, cable with thin braiding but the fix, other than tossing out for the right stuff, is just to do that.

Interesting.. I never tried folding the braid over like this to add more material to be crimped

[kerrsmith]

I have just had the same issue but found out it was the quality of the crimpers that made a difference for me.

I bought a set at about £20 which I thought would be OK but it turned out they hardly made a dent in the ferrule when crimping. The center pin crimped fine but the ferrule was very loose with only the slightest of crimping dents.

These were sent back and I decided to buy a set at just over £50 (took me a few days to convince myself I wanted to spend this amount on crimpers).

These new crimpers crimped the ferrules with a really noticeable hexagonal shape dent and were much better than the cheaper ones, they even put a hexagonal shape in the center pin where the cheap ones only made a square dent.

[rstor22]

These new crimpers crimped the ferrules with a really noticeable hexagonal shape dent and were much better than the cheaper ones, they even put a hexagonal shape in the center pin where the cheap ones only made a square dent.

With the crimper I am using now, I notice a hexagonal shape, though some outer ferrules are loose and slide off. With your new crimping tool, if you crimped a ferrule on a BNC connector with no coax/pin, does it crimp tightly or does it slide off?

[xavier60]

With my crimper, although the hex die is marked ".213", it measures 0.222". The crimped replacement ferrule measures 0.230" AF.

[kerrsmith]

I do not have any spare connectors to try this on at the minute, I need them for some new cables I need to make up for my latest project.

The crimpers I got (Paladin Tools PA1363 1300 Series) also have two other sizes that are very slightly smaller than the standard 0.213 RG58 BNC size - one is 0.197 and the other 0.178. When looking for a replacement I thought these would be good as if they were not quite right using the standard size I could try using the slightly smaller diameter hole.

So far the BNCs I have crimped were fine and so were the SMA connectors I made up a day or two ago so I have not tried crimping using the smaller diameter holes.

[rstor22]

I had that problem with cheap RG58 crimp BNC connectors I got on ebay. The  ferrule walls were too thin.
I got firm crimps with replacement  ferrules with correct wall thickness from another seller. 
https://www.ebay.com.au/itm/Crimp-Sleeve-Ferrule-Pleated-Tube-Pipe-For-RG58-400-RG142-LMR195-Connector/152692980958?hash=item238d35fcde:m:m1lUxkQNOvO4gNYs8VbhBOg:rk:1:pf:0

I ordered the ferrules that you linked and they arrived recently. They seem to crimp well (with the unknown brand bnc's that I have)  at level 5 (my crimper can be set up to 9). I did a test crimp with no coax. Thank you!
If I recall, the major difference between these and the ones (unknown brand bnc's with ferrules) that did not crimp as well was the OD ferrule measurement.

btw, the seller now lists them here:
http:/cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=143163451881

[CustomEngineerer]

The crimpers I got (Paladin Tools PA1363 1300 Series) also have two other sizes that are very slightly smaller than the standard 0.213 RG58 BNC size - one is 0.197 and the other 0.178. When looking for a replacement I thought these would be good as if they were not quite right using the standard size I could try using the slightly smaller diameter hole.

So far the BNCs I have crimped were fine and so were the SMA connectors I made up a day or two ago so I have not tried crimping using the smaller diameter holes.

I also use the Paladin Tools PA1363 crimper with PA2653 die for RG-58 and RG-174, and for both BNC and SMA connectors. I have not had any issues with loose connectors.