I have some RG-59 coax cable and I want to terminate it with BNC compression connectors. I bought some compression connectors, and what I think is a pretty good quality compression tool — the Liberty CM-TOOL. But every time I try one, it cracks the white plastic and bends the metal out around it. I tried to show what I mean in this picture. It sort of makes sense why the plastic cracking; the tool applies a great deal of force to that area. So how is this supposed to work?

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  • 1
    The bottom line is you are obviously using the wrong tool for the type of connectors that you have.
    – Michael Karas
    Aug 4, 2013 at 4:43
  • After all there are after all many sizes of tool dies for compression type connectors.
    – Michael Karas
    Aug 4, 2013 at 4:51
  • The tool likely has some adjustments so it can work with different connectors, do you have it adjusted properly?
    – Tester101
    Aug 4, 2013 at 12:32
  • Looks at the tool description it is meant to support BNC but has a reversible die. Have you tried reversing the die?
    – Jason
    Aug 4, 2013 at 13:43
  • I wonder if you are using the wrong impedance die. BNC connectors come in both 50 and 75 Ohm, the difference being the diameter of the plastic bit which is being damaged. (I've never crimped the connections, so I could be wrong here). Your tool can be flipped to go between F, and BNC/RCA connectors.
    – Pigrew
    Aug 4, 2013 at 14:23

1 Answer 1


There's a large variety of compression tools and connectors, and unfortunately they aren't all compatible with each other. Most likely you'll need to use a different tool or connector style to make a proper compression fitting. But a few tips from the last time I was installing coax connectors:

  • Make sure the tool is properly adjusted, especially with the depth.
  • Fully seat the connector inside the tool so you get 3 sides secured where the cable exits the tool.
  • Select the correct die if you have a choice and properly align the end of the connector with the tool.
  • If you aren't sure of the depth or start to warp or bend the connectors, only partially compress the fitting, spin the cable so other sides are being stressed near the cable, and adjust the depth until you have reached full compression but no further.

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