Rivet nut thread pulling off centre

[Simonpiemon]

Good morning,

As title explains, I'm fitting flush steel M3 rivet nuts to 1.6mm 12x12 box section. Every attempt results in a completely off-centre thread or if I'm lucky it's somewhat centred.

I'm holding the tool completely straight, and attempted to use washers between the rivet and the thread on the rivet tool to no success along with other techniques. The hole is exactly the same size as the rivnut and countersunk to match the rivnut. Is there a special technique im missing or is this just the nature of how rivet nuts are? Like when a coke can is crushed it will always fold and distort unevenly as it's being squashed. The rivets are from a reputable dealer who specialise in fasteners although I'm tempted to try a few different brands.

I've contemplated just tapping the box section M3 but 1.6mm is a bit thin in my view. The threaded holes are to secure a 1mm plate with door handle for some metal doors im making and will only require tightening once.

Any help would be much appreciated.

 

[Ton-up]

One thought - Have you made sure there is no burr on the back of the hole in the box section? If you have a blunt drill or countersink you can have a burr or deformed edge and as the rivnuts are so small, it may send them off.

 

[daedalusminos]

As @Ton-up states, make sure there's not a considerable burr on the reverse = worth slitting your box open so you can see what going on.

Can you get rivet nuts design for thinner sheet, by countersinking you're probably getting to the point where it's at the end of its collapsing range. I had a similar problem with some M10 ones in 1.5mm box and made up a press tool to press the counter sink in...

D

Post in thread 'Rivet nuts'

Jan 30, 2026

Made up a press tool to press the countersink in, works a treat...

• daedalusminos

• 

 

[tigdlo]

A shorter rivnut may help, reduced head rivnuts are also available, they work with a smaller countersink.

This one works down to 0.5mm https://www.rivetwise.co.uk/rivets/...head_serrated_euro_open_rivet_nuts_steel-1020

 

[Craig-SM]

Put some tape around one of the handles on the rivnut tool and try using it with the taped handle in the left and right handle to see if affects the angie of the thread. You stated you’ve made sure it’s square but when you squeeze handles I’d be surprised if the force on the handles are equal as you’ll have natural stronger arm but the tool may have slightly less leverage to one side too. If that’s the case finding out which is the stronger side and reducing the leverage by holding that handle lower may keep it square.

 

[Simonpiemon]

Thanks for all the help so far I'll give the internal hole a good debure, and try a shorter rivnut with the smaller countersink as well as the other techniques mentioned above. If push comes to shove I can weld a small piece of metal inside the box to increase the wall thickness to around 4.5mm but this seems like a faf!

 

[Agroshield]

In addition to all the above good stuff, cut out a section of box and watch it from the back as you close the nutusing the tool.

I guess you are not installing into the side of box that has the welded seam?

To eliminate the tool, use an alternative means to close the rivnut as an experiment

 

[voipio]

Could it be a bad batch of rivnuts? I've had some that tended to go like that, and others that have been fine.

 

[MetalMonkey]

Try putting one in without a countersink and see if it pulls up straight.

 

[Dapph2]

Use a washer and threaded bolt and spanner to set one on some scrap the same thickness and see if it is still cockeyed . And as said earlier make sure you are not rivinutting into the side of the tube with the weld seam in it .

 

[Wallace]

Is the shank on the tool the same diameter as the thread?

 

[bricol]

The hole is exactly the same size as the rivnut and countersunk to match the rivnut.

I suspect this is the issue - hole and countersink size should be specified in the documentation for the riv-nut. I doubt its an exact match.

Are you using a riv-nut suitable for the 1.5 thk material - riv-nuts have different grip ranges.

Having said all that - at M3, does it matter? Will it pull the screw head flat on tightening anyway?