Originally Posted by
tls25rs
You could make a ghetto one out of a longer bolt with a nut and a washer.
Put them in this order
relatively longer bolt (pass/thread this through the following in order)
nut
oversized washer (washer needs to bigger than the outside diameter of the rivnut to work properly for this)
rivnut
insert the rivnut into the material you want to install it into, put the washer down on top of the riv nut, spin the nut down to the washer, hold the top of the bolt stationary with a wrench or socket while you tighten the nut down onto the washer with a separate wrench. Hold the stack up of items tightly into the hole you are installing it in and crank down on the nut. This will draw the bolt that is threaded into the rivnut up towards the surface of the material you are installing it into and expand the back of the rivnut just the way a rivnut insertion tool would do. When it is tight enough that you are comfortable with it, back off the nut and washer and then spin the bolt out of the freshly installed rivnut.
This also works for tightening up rivnuts that have started to spin in the subframe of a bike or wherever else they may have been installed.