Thread: Rivnut/Nutsert Experts?

Originally Posted by SurfinNev

Just had another thought. I would add some never seize to threads to prevent corrosion and to make the bolts easier to remove if necessary.

Actually had the same thought - if a rivnut does spin, I'm kind of screwed. I could grind off the head of the bolt, and then drill out the rest, but it would be pretty ugly. Anti-seize seems like a wise precaution.

I saw what I wanted rivnuts for today. SWMBO's Rodeo has one of the rope tie downs on the side of the tub hanging loose. The screw has pulled out. It has a plastic protective bit under it which hopefully should leave room for the head if I cut a hole in it.

Dean

Nothing more annoying than one that spins when you try to undo the bolt. For really critical applications I've TIGed a few tack welds arond the flange. Not so pretty but they don't spin. Not so practical for the countersunk flush mount ones.

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That's why they do hex ones as well, Holden use a lot of them, it's a bugger drilling a hex hole in sheet though.
Kryn

So I used my rivnuts for the first time:

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Seem to work well - I discovered that if you over-tension them with the tool, they collapse to the side a bit, so I developed a feel for how tight was enough.

I can see a few other places where they'll come in handy, so getting a bag of 50 off Ebay maybe wasn't excessive after all

An suitable alternative to rivnuts is to thermally drill the holes. The thermal drill forms a flange that can then be form/roll tapped. I've only ever thermally drilled with a drill press, and don't think anything like a mag drill or hand held drill would be suitable. It therefore means the holes may need to be created before further construction so the RHS can fit in the drill press. Sheets etc would likely be problematic, so it's certainly not for every application but has significant benefits when it can be used.

I think the trick with that is you need a fair few RPMs plus pressure to get the heat, which *might* be possible with a hand drill on a good day with a tail wind. From memories of seeing them on YouTube, they don't have the shoulder to deal with like you have with rivnuts, but I think they're really suited to production environments where you can set up to run large sections through a drill press.

Originally Posted by RustyArc

if a rivnut does spin, I'm kind of screwed. I could grind off the head of the bolt, and then drill out

No point in trying to drill it out if it spins, it'll just keep spinning with the drill bit. Punching it out would probably be the best bet.
An other option to Rivnuts, is to use some bar with a thread inside, similar to a seat belt mounting bung. Seat belt bung.jpg
Have made many of these for seat belt mounting points and bolt on points for pipe and RHS, drill the hole through the metal, insert the "bung" and weld both sides.
Kryn

If it spins, sometimes a tack weld will hold it well enough to drill it out. Otherwise grind off as much as you can and punch it in. All not very elegant but might get you out of trouble.

I've used a lot of M3 nutserts and they need a deft touch with the tool or you either deform the thing, or you strip out the thread. Not so much of a problem with M6 and above. I don't think any size takes a great deal of torque, either doing it up, or trying to undo it (esp when it gets a bit corroded). If it is a critical application, I tack it on with the TIG. Probably overkill, but I sleep better knowing it wont spin.

I like your idea Kryn. The weld gives you some confidence as does a good length of thread in the bung. Good suggestion, thanks.

Never tried those thermal drills. If you get it to look like (and work like) the promotional video, I imagine it would work a treat in the right application. The bits are expensive though. And, I take on board those who say that it needs a lot of pressure and speed to heat up and distort the metal.

Yes, a hex rivnut/nutsert would be great. I have battled making good hex holes (or even square ones) over the years - wish it were easier, as there are lots of projects that have called for them (I'm thinking blind hex or square holes in thick material, not in sheet, where a file can still get you a reasonable result - if not a bit tedious if you have to do lots of them). Not a topic for this thread, but I would be interested if anyone has solved this problem with a cunning home made tool.

Tony

I was thinking about running around with the TIG and putting a tack or two on the shoulder, but they're set into Duragal, which reacts poorly to TIG.

Originally Posted by Silversprings

Yes, a hex rivnut/nutsert would be great. I have battled making good hex holes (or even square ones) over the years - wish it were easier, as there are lots of projects that have called for them (I'm thinking blind hex or square holes in thick material, not in sheet, where a file can still get you a reasonable result - if not a bit tedious if you have to do lots of them). Not a topic for this thread, but I would be interested if anyone has solved this problem with a cunning home made tool.

Tony

You can make a rotary broach to do this. YouTube search will find them. You might be able to buy them too but I don't know where.

Dean

Originally Posted by Silversprings

Never tried those thermal drills. If you get it to look like (and work like) the promotional video, I imagine it would work a treat in the right application. The bits are expensive though. And, I take on board those who say that it needs a lot of pressure and speed to heat up and distort the metal.

Tony

Tony beware of what you often read on the internet. Too often people watch a couple of Youtube videos before declaring themselves experts in the subject and pontificating their opinion as if the world has been waiting for it.

I have thermal drills in sizes M4 to M8 I believe. The price may seem expensive until you consider there is essentially no ongoing cost with them, and they will drill around 10 thousand holes without any sharpening. I think I bought mine through Aliexpress IIRC, they're also known as Flow Drills (a bit like a "Hoover" after the company that initially developed these) or friction drills. You'll also need to factor in the cost of form taps, but I got mine from the same source and they were inexpensive and the quality good. You would be able to use a regular tap, but it will remove material instead of further forming it, so it's not in the interests of this process.

Contrast that to buying a rivnut setter from Bunnings at $100, and then if you buy rivnuts from the same source they work out at around 40 cents each. An alternative is obviously to buy them through the internet, considerably cheaper, but there is then a delay and unknown quality. A couple of weeks ago I bought a couple of hundred self-drilling S/S countersunk screws for a job and they were so soft they wouldn't even self drill. I finished up having to drill pilot holes for every one, and then discovered the threads stripped when they were set in standard RHS. That was 40 bucks worth of fasteners wasted, plus a large bunch of my time I don't have, as not only were they slow to set, I had to go through and try to get many of them out again to replace them with screws I got at work. They were from an Australian seller as I needed them quickly. Anyway, the moral of the story is there's a lot of crap sold through the internet, so "cheap" rivnuts may of may not be worth the while in the ebay lucky dip!

As far as extreme pressure and super high speeds, that's just crap. The speed is at the top end of what a home shop drill press is capable of, but I've certainly done it on mine. The pressure is nothing exceptional. A lot of good information is available here. Formdrill: Introduction to Thermal drilling The reason it probably wouldn't work well in a hand drill is simply that the drills don't tolerate any axial loading at all, and will likely snap. Being carbide, when these snap there's no re-sharpening them, and they get thrown in the bin. Don't ask how I know that.

I don't think thermal drilling is for every application, and if I had to suggest buying either a rivnut system or Flow drill system, I'd say the rivnuts would be the way to go. However when the job is right, thermal drilling is an excellent process that produces very strong threads at no ongoing cost and is extremely fast.

Originally Posted by RustyArc

Actually had the same thought - if a rivnut does spin, I'm kind of screwed. I could grind off the head of the bolt, and then drill out the rest, but it would be pretty ugly. Anti-seize seems like a wise precaution.

If it spins, have you tried re-setting the rivnut?

Originally Posted by RustyArc

That's the guy I've ordered off - he's just sent me a photo of the satchel

I'll have to try and see how hard the M10 ones are to crimp - the tool I have is a two-armed unit: https://www.kincrome.com.au/nut-rive...-handle-68-pce

But I agree, stainless is probably a bridge too far.

For larger nuts you may consider something like this STEALTH Nutsert / Rivnut Air Hydraulic Tool Rivet Nut Riveter Gun Tools Garage | eBay I don't have one but would certainly consider one when I get anything more than just a few rivnuts to set. I think the price is quite realistic. I have a very similar pneumatic rivet gun and it's one of the best tools I've ever bought. The difference between using it and a hand riveter is night and day, and something I always hated doing (setting rivets) became a true pleasure and super fast. I virtually never set rivets by hand these days unless there's just one or two to do. I'm sure it would be the same with the rivnut version.

The only issue I have with them is the nut needs to wound on and off by hand. Not such an issue when putting the nut on the mandrel, but a PIA once the nut is set as not the machine is hanging off the (now set) nut. There are fully-automatic versions available that wind the nut on and off, and I believe they're excellent, but have never used one myself. They basically combine a pneumatic riveter with an air drill in the same unit, so it will both pull to set the nut, and spin the mandrel to spin the nut on and off. I've never seen one that is what I could consider in my budget, which is a shame as they're the ducks guts when it comes to this type of thing.

Originally Posted by Pete F

If it spins, have you tried re-setting the rivnut?

This is all theoretical at the moment - I've only just installed my first 2 dozen or so rivnuts, and won't really know if I'm in for a bad time until I come to undo them at some unknown point in the future.