Rivet nut failure

[tjbrace]

I have 2 rivet nut inserts in my mast to secure the gate blanking plate. One of these has failed and just turns in the mast. There is a machine screw partially in the rivet nut but the nut turns with the screw when i try to unscrew it.
Can anyone suggest 1) how to get the screw out, 2) how to resecure the nut, and /or 3) how to replace the rivnut.
Many thanks.

 

[chris-s]

First idea would be too cut off the screw as flush as possible and then grind it all back until you can tap it into the mast and allow it to fall down?

 

[Norman_E]

I have 2 rivet nut inserts in my mast to secure the gate blanking plate. One of these has failed and just turns in the mast. There is a machine screw partially in the rivet nut but the nut turns with the screw when i try to unscrew it.
Can anyone suggest 1) how to get the screw out, 2) how to resecure the nut, and /or 3) how to replace the rivnut.
Many thanks.

The hardest part will be getting the screw out, because there is most probably little of the rivnut to hold on to and stop it turning. If you cannot hold it sufficiently to undo the machine screw then you need to pull the screw in order to get the rivnut a bit more compressed. Just pulling is no good, and more likely to deform the aluminium mast locally, instead of re-setting the rivnut. If the machine screw is a long one, cut off its head and put a washer followed by a nut on it, then grip the exposed end of the screw with mole grips to stop it turning and use a spanner to tighten the nut really hard against the mast. That will expand the rivnut and make it grip and you will then be able to remove the cut off machine screw after slackening the nut. If the machine screw is too short for the above I would make two slotted steel wedges to fit between the screw head and the mast, and force them together with a strong clamp so as to pull the screw and apply force to the rivnut.

 

[superheat6k]

If you have any thread showing on the bolt then cut the head off and wind on a nut, hard into the rivnut, this might re-nip the rivnut enabling the thread to be unwound, and then drill or punch out the rivnut remnant - the outer head of the rivnut could also be ground careful with a Dremel. Then either a new oversize rivnut, or re-position a new one into fresh metal.

 

[BabaYaga]

I had a similar problem a few months ago, posted a question on here and got a bunch of useful suggestions. This thread:
Rivnut turning – best course of action?
In the end, my attempts to get the bolt out or to reset the rivnut failed, so I cut off the flange of the rivnut with a hacksaw blade (put some tape on to protect the mast surface) and knocked the assembly into the mast.
Now have a clean hole and new rivets to install...