Rivnut spinning

[RJJ]

Hello. My first attempt at rivnutting. I thought I would be a smartass and dodge buying a rivnut tool; I wound it on using a spare machine screw, spare nut and washer.

The first one worked a treat.

The second one...not so much. Gained sufficient compression to hold the rivnut in the mast but not enough to stop it spinning. Grrrrr. Looking inside, the threads are full of claggage; I guess I could clean the threads and try tightening it some more, but of course to clean the threads I would need the rivnut not to be spinning.

What next? Many thanks. Should I cut off the existing rivnut or drill it out,.or is it worth trying to secure it to the mast somehow?

The end purpose is a single mast step about three feet above deck level.

 

[harvey38]

Mole grips to stop it spinning then run a tap through it with plenty of lube to wash away the "Claggage" making sure once the tap has started you go in gently going only fractionally more clockwise then unwind and flush out.

Once that's done, USING A PROPER TOOL, compress the rivnut fully.

 

[Daverw]

I tried this a while ago, also managed one well but the other two a disaster, then went to machine mart got the proper tool and realised how easy it is then, and quick,

 

[BabaYaga]

I seem to remember that you can 'preset' the rivnut just a little before introducing it to the hole. The slight expansion might stop it from spinning.

 

[Stemar]

Hello. My first attempt at rivnutting. I thought I would be a smartass and dodge buying a rivnut tool; I wound it on using a spare machine screw, spare nut and washer.

The first one worked a treat.

The second one...not so much. Gained sufficient compression to hold the rivnut in the mast but not enough to stop it spinning. Grrrrr. Looking inside, the threads are full of claggage; I guess I could clean the threads and try tightening it some more, but of course to clean the threads I would need the rivnut not to be spinning.

What next? Many thanks. Should I cut off the existing rivnut or drill it out,.or is it worth trying to secure it to the mast somehow?

The end purpose is a single mast step about three feet above deck level.

If you're anywhere near Southampton, I've a rivnut tool you can borrow for your next attempts.

 

[RJJ]

If you're anywhere near Southampton, I've a rivnut tool you can borrow for your next attempts.

Thanks Stemar. M8 rivnuts OK? Have PM'd you.

 

[Stemar]

I'll check & get back to you

 

[TernVI]

SS or Ali rivnut?
Once it has spun in the hole a bit, either the rivnut wears or the hole gets enlarged.
If you can't hold it still to clean the thread with a tap and wind in a hex head bolt, then I'd dremel it away before doing any more damage to the mast.
Top tip, practice bodgery on something scrap.

M8 is a bit serious, M5 wouldprobably have done the job.
To set a rivnut with a bolt, you need to thread in a hex head bolt with a nut and two washers on it. hold the bolt still and wind the nut down.
There are many different flavours of things we call 'rivnut' some are very easy to set like this, others are impossible, I'm not sure I'd attempt it with anything that actually needed M8.

 

[Graham_Wright]

I have used a "proper" tool on M8 stainless rivnuts. It didn't last long. Choose wisely.

 

[TernVI]

I have used a "proper" tool on M8 stainless rivnuts. It didn't last long. Choose wisely.

A proper tool for M8 stainless rivnuts sounds like a hydraulic thing in a factory with a trained technician attached!

 

[RJJ]

SS or Ali rivnut?
Once it has spun in the hole a bit, either the rivnut wears or the hole gets enlarged.
If you can't hold it still to clean the thread with a tap and wind in a hex head bolt, then I'd dremel it away before doing any more damage to the mast.
Top tip, practice bodgery on something scrap.

M8 is a bit serious, M5 wouldprobably have done the job.
To set a rivnut with a bolt, you need to thread in a hex head bolt with a nut and two washers on it. hold the bolt still and wind the nut down.
There are many different flavours of things we call 'rivnut' some are very easy to set like this, others are impossible, I'm not sure I'd attempt it with anything that actually needed M8.

Many thanks.

Yep, the mast step calls for an M8 bolt.

 

[ghostlymoron]

The force required to shear three 5mm bolts/ set screws is huge 8mm is way over the top. Go smaller.

 

[Graham_Wright]

A proper tool for M8 stainless rivnuts sounds like a hydraulic thing in a factory with a trained technician attached!

It was the threaded "puller" that sheared.