Rivnuts?

I have a set but have only used them once to bolt up a cover on an outside compressor. The main fault is that the nut if it goes in soft materiel like Alu. will rotate and destroy it's ability to hold and be difficult to undo as the nut turns as well.

Seems to work in steel sheet though.

Clive

Hi Mark, I can assure u that they work a treat......

I tend to buy just the stainless sort......that kit with those pop-rivet type pliers are ok but if u want to use them on a regular basis get a heavier plier setting tool....mine is the concertina type.....I would say, that set properly they are as strong as nut's in shear but not quite so reliable in pull out situations but Ok for light loading..........

ONE thing to point out that the hole they fit in HAS to be very accurate in size, u only have a 1/4 mill for a good fit....to tight, u can't tap em in....to loose and the set is not so good......they are available to suit various thicknesses of metal and with or without a counter sink head..........

I have some that can be used in 10mm thick plate.....for this job in question it was use these nut's or drill and tap about a hundred 10mm bolt holes working of a ladder.....on that job I only used new drill bits....once they started to blunt ---change em....if the drill fluts get worn i.e. with thick metal u get probs with the fit of the nut's....on thin metal not such a problem....after u've done a few u get the feel of them....even some times a quick flick with a file will just clean up the holes enough.....they are life saver at times......

Clogs

Yep another thumbs up from me for them.....

Used them when assembling inverter controls for lathes and milling machines for mounting DIN rail, vfd and terminal blocks....found them a great way of holding it all together.....Once assembled into the enclosure, if anything needed removing, no nuts to lose....

Certainly not a gimmick; I only have the tool you see in the photo, but it works fine up to 6mm.

If access is tight, you can make up a one off tool using a nut and allen bolt to compress the insert.

I just wish that the chap who built my Marlin kit car had discovered them, rather than using loose nuts and washers that need a major stripdown to get anything off.

All the best

Bill

The best of them require a punch to make the hexagon hole that prevents the nut turning, don't know if this type is still available, the other type of nut has an oval flange, with a hole each side so that it can be riveted in place, this one has an "AN" number AN 361-362-366-373, Nut Plate, self locking, it's probably obsolete, and now will have a NASA number.

UNF/C thread.

Ian S C

Should be made illegal. Used in cars to speed up production but make the item unmaintainable once a bit of rust has jammed them.

I use em all the time great fixings for panels etc.

I take it these are similar to the threadserts you get with a serrated flange for placing threads into thin sheet metal, they're very expensive I think, and me being el cheapo, I wouldn't have had the job to warrant it or luxury to peruse it!

Michael W

Hi Bazyle,

that's why I only use St/Steel rivnuts plus in general everything under 8mm dia I always use St/St fasteners anyway that's unless of course it need's high strength.......

St/St fasteners bought in bulk are almost as cheap as Zinc plated......if you have too......look at Screw fix prices and let's face it most general fastener's are made in Asia anyway and nobody will admit it.......

Clogs

It can be surprising where things come from, I had an operation when I was young for little plastic rings fitted in my ears, they call them gromits. And I was only told about 20 years down the line that they were made in a factory in my hometown, one of only two suppliers in the united kingdom. Not only that, but I was working for them! They sold them to the middle man for about 20p each, then they put a mark up of about £80 to sell to the NHS, criminal really.

But off the bat, i'd say most people would admit their stuff is made in Asia, they're just crazy keen on manufacturing I guess, unlike here, it's not so much the cost of making but the fact it's just become an unpopular thing to do in the UK. And the only people who do so, are the ones who break the mould. 

I've spoken to people who manufacture in a small scale china and they aren't exactly rolling in cash, infact they're probably just turning a small profit if not just turning over. They haven't really got it any easier than us. They just want to do it. 

Michael W

Edited By Michael-w on 13/05/2017 12:49:19

Huge variety of the things. Work really, really well if you choose the right one for the job and install it exactly as per specifications. Which, realistically, Home Shop types aren't going to be able to do. If nothing else most of the high performance ones can't be got in small numbers although some of the automotive ones can be found as manufacturers spare parts. At a couple of £ each if the ones I got for my P38 Range Rover are typical.

Plier tool kits tend to come with general purpose, light duty, types intended primarily for panel fixing and holding up fairly lightweight things with multiple fixings. Don't have to be that fanatical about the lightweight side of things, big panels can come out heavy, but I'd be chary about anything over one hand lift weight. The multiple fixing thing is essential tho'. You really don't want the rivnut twisting during installation or when whatever its holding get knocked as any shift seriously reduces its torque resistance and will almost certainly make the fixing irremovable without very serious attention. Important not to over torque the screw or bolt. Some determined nooging around the internet should unearth figures for ones similar to what you have. Way back I was told, possibly by a visiting rep from RS Component (remember them), that something around half maximum torque for that size brass fitting was an appropriate maximum for those they sold. Which, for small screws, isn't much.

You must have a clean hole neatly de-burred on the back. Ideally with a nice sharp corner. In my experience the de-burring and sharp corner bit is where folk get into trouble with blind holes. All seems very variable. Sometimes Mr "I'm in a hurry so its gotta do" can get away with absolute murder and sometimes Miss "usually very careful" gets bitten after what should to have been a quite adequate installation. Really don't want them to turn during installation which is why the bolt and nut trick can drop you right in the kitty litter as can trying to improve the grip by tweaking up the bolt a bit over tight. The grip comes from the collapsing part both mushrooming over the back of the hole and simultaneously expanding to wedge inside the hole. Indeed some types, intended for thicker materials, just wedge themselves in the hole without the mushroom over the back. The wedge in the hole effect is why you need to use the appropriate fastener for the panel thickness. Curious Clive tried a few wrong 'uns and was a bit surprised at how much difference it made.

I think it best to lubricate the fastener with coppaslip or similar. Other folk swear by sealing the threads with the lowest strength loctite. Been known to anoint the hole with supaglue for a bit of extra torque resistance, most likely the feel good factor vastly outweighed any real world gain.

Bottom line is that rivnuts are very forgiving if you don't push the envelope too far too often but that forgiveness means its easy to get in the habit of expecting too much too often. Bit like over torquing bolts. Usually you can go beyond the official limit but eventually you get bitten.

Clive.

I have a small stock of aluminium Rivnuts, up to 8 or 10 mm. They're the flanged type, not the countersunk type. I have the pliers-type fitting tool and also a telescopic long-arm tool.

Surely, a few irregularities in the back of the hole would help avoid rotation? You'd need a Guiness before fitting the stainless variety!!

I bought my Rivnuts (at least 20 years ago) from a firm based in Todmorden, I believe they traded as 'Riveting Systems'. (Usual disclaimer, no connection except as a satisfied customer.)

Best regards,

Swarf, Mostly!

"a firm based in Todmorden"

Their brand name was King Klic

Irregularities at the back of the hole may well help stop rotation by engaging in the mushroomed bit. But an irregular hole, whether in bore or on surface, will interfere with the collapsing and grip behaviour in a manner reducing the frictional hold. If you gain more from grabbing the irregularities than you loose from imperfect collapse then the overall effect would be to increase maximum torque before rotation. Conversely if you loose more by imperfect collapse, clearly maximum frictional grip requires the collapse to be perfectly symmetrical, than you gain from physically engaging in irregularities the maximum torque will be lower. Completely unpredictable in practice which is why careless drillers get such variable results.

In the real world serrated and hex bodied versions use engineered irregularities to improve torque capability. Usually such need more ooph than a simple manual plier or, for larger ones, lazy tongs installer can apply. Pneumatic installers seem to be the professional weapon of choice. Usually with controls to set the installation force to what the insert maker decrees.

Seems to me that the screw driven opposed pair of sliding wedges style of installer would be effective for types that need higher forces. Pretty easy to make something that would work off a back of the envelope sketch. But it would be nice to have some idea of optimum wedge angle and how bolt torque translates into installation pull. If splashing out on good ones it seems sensible to fit them properly. After all higher end versions have rated torque capabilities significantly exceeding the shear level of ordinary bolts.

Clive.

Correction: King Klik

Clenching tool can be replaced with a cap screw and hex nut if you're not fitting many.

Regards Ian

I use M5 rivnuts all the time. I use the ribbed ones with thin sheet heads. These need a 7.1mm hole, put I usually use the fly-press with a 7mm hole punch. Then lightly countersink the head side of the hole. I have fitted at least a 1000 of these over last 4 or 5 years. The tool looks like a direct copy of the Eclipse version (which I use).

A good site to take a look at is "Make Ends Meet" (www.memfast.co.uk), they have other types of rivnut installer and hold a full range of rivnuts. I have no connection other than a very satisfied customer.

Colin

If it is only a one off, at a pinch, you could make one.

At work, a M6 one failed, through abuse, (overtightening). Having managed to get out the remains, tapped a piece of 1/2" dia.steel, and then turned down the OD to a snug fit in the damaged hole, and parted off to leave a flange. Fixed in place using a M6 setscrew and nut. Having removed the setscrew and external nut, the handle on the roller cabinet was refitted. With the cabinet being double skinned, it was not possible to use just a nut on the inside, so it had to be self clinching thread..

Howard

Edited By Howard Lewis on 17/05/2017 21:04:58