pnumatic rivnut gun for small metric threads (m2.5 m3 etc) ?

[julianf]

So, i need to do some M2.5 rivnuts. I assume they exist, but ive not found them just yet. M3 certainly does.

But...

Rivnuts are pulled using their own thread, right?

So, when buying a gun, i need to find one that has tools to match the rivnuts that i want to install? Not a load of random american threads, like the guns above.

And thats where it all starts to go wrong.

Anyone got any pointers?

Thank you

 

[The_Yellow_Ardvark]

Hand held too will give you better control.
The M3 ones we used with Pallfinger gear would strip out if to much grunt was used.

If it is one or 2, try using a bolt and washer trick.

 

[James1979]

I use the hand tool from FAR. Do you need a pneumatic one? Mine is just a selection of threaded mandrels so you could turn one up to fit any gun you bought.

I know mine does M3, can look and see if it’s m2.5 if you want but I don’t think it is.

edit. It’s M3. Don’t even off 2.5 as an option. https://www.far.bo.it/en/products/riveting-tools-for-blind-rivet-nuts.html

 

[123hotchef]

dont see M2.5 rivnuts normally

 

[julianf]

I can use #4 UNC if i can get them - pretty much the same OD as m2.5

 

[hotponyshoes]

On all the pneumatic ones I have seen, once they are set up properly for that job there is some form of stop so there is no chance of pulling the thread out.

I have never seen 2.5 mandrels for any of them though. Some tools have much more complicated front end parts than others so do a bit of research first as if you get the right type it would be easy to make your own parts for it.

Presumably you have a lot to fit to justify a powered gun? If you have enough to justify the setup/testing time then there are other ways to set them. On 2.5mm you could probably use a torque controlled driver or even adapt a rivet gun maybe?

 

[hotponyshoes]

Another option would be to use the hank type nuts. They are available in 2.5mm.
You can set lots of them easily enough using a cordless drill and a thrust bearing but you would need access to the back side of the panel to install them.

 

[The_Yellow_Ardvark]

Another option would be to use the hank type nuts. They are available in 2.5mm.
You can set lots of them easily enough using a cordless drill and a thrust bearing but you would need access to the back side of the panel to install them.

Or let's be mean and suggest Zeus fasteners

 

[julianf]

Another option would be to use the hank type nuts. They are available in 2.5mm.
You can set lots of them easily enough using a cordless drill and a thrust bearing but you would need access to the back side of the panel to install them.

Yes, I'm currently using those folded clip things with the thread cut in the back side of them, but they are horrible to install in numbers, and I've got another application where the requirement for an easily replaceable thread is not as important.

These parts need to be installed into a folded lip (the top of a folded box) in order to hold the panels that I usually make.

The lip is only 10mm wide (I can't change that) and those folded captive nut things are longer than that, so you have to rotate them 90 degrees,and cut a slot for the fold, and it's all just a bit more than I want to get into for a new design, that, again, does not require the user serviceability of standard captive nuts.

So I figured buy the setting tool and away....

The Hank nuts. I've googled and got a photo. Do you hold them with a spanner on the inside and then screw somthing into the visible side to fold over the lip?

I have both a cordless drill and impact driver.

Thank you.

 

[hotponyshoes]

The hank nuts are available in various sizes to suit panel thickness as well as the thread size.
If you can get the insertion hole the perfect size and burr free then you don't need to hold them with a spanner. If the hole size is bang-on then you can push them in and they will stay in place by themselves.
You just need access to the back to insert them in the first place (unlike Rivnuts which you insert from the front)
For a fixing tool get a 2.5mm high tensile socket cap bolt. Hold the cap in a drill chuck, slide a thrust bearing over the bolt thread and hold it in place with an o-ring.
Hold the hank nut from behind and wind in the bolt from the front. Set the clutch on the drill to slip once it's set but before the thread rips out flick into reverse and wind out.
Some sort of lube on the cap bolt threads makes it last a lot longer.

 

[hotponyshoes]

Or..
Find out what tap size a 2.5mm helicoil uses
If it happens to be something common like m5 you could fit a normal rivnut and chuck the helicoil into it.

If you can find Rivnuts in 2.5mm I have got a pneumatic gun that's missing all the mandrels. You could buy that off me and make up your own 2.5mm end for it

 

[julianf]

Or..
Find out what tap size a 2.5mm helicoil uses
If it happens to be something common like m5 you could fit a normal rivnut and chuck the helicoil into it.

If you can find Rivnuts in 2.5mm I have got a pneumatic gun that's missing all the mandrels. You could buy that off me and make up your own 2.5mm end for it

That seems like a good idea.

This seems to be a m2.5 helicoil -

But now i need to make sense of this -

 

[julianf]

ughh... images loaded in preview.

helicoil seems to be 3.2 - 3.7 major diameter -

M2.5 x 0.45 x 2.5mm Helicoil Insert - 25 per pack

M2.5 x 0.45 x 2.5mm Helicoil Insert - 25 per pack

www.rivetwise.co.uk

 

[hotponyshoes]

That seems like a good idea.

This seems to be a m2.5 helicoil -

But now i need to make sense of this -

Um?
At a guess, the value of H ÷ 2 then + 2.5?

Helicoils are fairly springy so you can get away with a bit of variation on the cut thread size but it obviously effects the size of the internal thread that you end up with.

If it's 3.2-3.7 required then an m4 rivnut is not likely to work.
You could fit a 3mm rivnut, run the correct helicoil tap through it, then fit a 2.5mm helicoil but that's a load of extra work...

 

[julianf]

probably not so bad if i can re-size using a tap in a drill and it follows the existing thread without a significant failure rate.

but, yeah, the hank nuts are seeming a better plan with every additonal process!


Your gun with the missing mandrels - are they all gone, or does it even have a single one to copy?

 

[hotponyshoes]

An even simpler way might be to use a self-extruding screw?

TR product news | TR EPW Self-Extruding Screw

The EPW Screw is a self-extruding, high strength thread-form fastener which creates its own female thread in punched sheet metal.

www.trfastenings.com

Not sure if they go down as small as 2.5mm though?
If they did you could just form the thread with one then replace with your own choice of fastener afterwards.

The gun I have got does not have any bits to copy. It came from an aerospace place and they had some sort of custom made tooling fitted to the front of it but they would not let me have that bit and they couldn't remember what happened to the bits they took off.
It's a decent one, bollhoff I think, so all the spare parts will be available.
There is probably enough detail in the parts catalogue to make your own bits up without needing anything to copy.
I can dig it out tonight and see what's needed if you like

 

[pedrobedro]

Or let's be mean and suggest Zeus fasteners

Or even Dzus fasteners

 

[mike os]

I would try to go to m3

 

[Wildatlanticwelder]

Would a 2.5mm pop rivet or a self tapping screw work for you?