Hex Hank Rivet Bushes

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PeteThePen1
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Hex Hank Rivet Bushes

Post by PeteThePen1 »

Good Morning Everybody from a very damp Cymru.

I have been advised to join the panels of the casing for the mono-tube boiler I am building with Hex Hank Rivet Bushes. These are new to me and having seen them now on various websites, eg. https://www.kayfast.co.uk/view-product/ ... LESS-STEEL I would tend to agree with the advice.

However, I cannot see how the 'nut' element is secured to the sheet metal. Am I right in assuming that the word 'rivet' in the name also implies that one has to bash them in some manner to get the non hex side to expand? Are there special tools for doing this or could/should one turn up some kind of a punch on the lathe?

I would be most grateful if you could share your expetise in this context.

Regards

Pete
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dampfspieler
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Re: Hex Hank Rivet Bushes

Post by dampfspieler »

Hi Peter,

i have found some interesting links.

Hexagon Rivet Bush installation knowledge base

https://youtu.be/TQ8NczwGeAo?si=bol4fTf9wwZlzxCC

Hope it will be helpful

------
Dietrich
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PeteThePen1
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Re: Hex Hank Rivet Bushes

Post by PeteThePen1 »

Hi Dietrich and Friends

Thank you for the link. That is a very useful site, and to save anybody who is interested from much searching there is a page that specifies the dimensions of the necessary punch to 'peen' the nuts and secure them into the sheet metal. The drawing is intended for folk with proper hydraulic presses, but one could just as easily use the profile for a hand punch. It looks as if one punch can handle several sizes of Hank rivet. [https://www.trfastenings.com/knowledge- ... sh-tooling]

I will have a go at drawing it and checking the angles etc.

Best wishes

Pete

Postscript (15Nov23) - I have started to draw the press tool based on the above website data. However, the missing data relates to the tip of the punch. Nowhere does it say how long the critical element is meant to be nor the radius of the curve it should have. Looking for suppliers of such punches I came across a hank nut supplier whose page extolling their virtues said "Ideally Rivet Bushes should be installed using a press with a suitability profiled punch by applying a parallel squeezing force, however they can be installed using a hammer and ball bearing to form the spigot profile." So for us DIY folk it may well be simpler to buy a suitably sized ball bearing from eBay or similar and get out that lump hammer we seldom use!
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PeteThePen1
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Re: Hex Hank Rivet Bushes

Post by PeteThePen1 »

Hi Folks

I have been hunting online for Hank Nut press tools and have found none that have a price tag. No doubt the old addage that "if you have to ask the price then you cannot afford it" probably applies.

However, as always the internet is keen to sell me stuff and I have been introduced to the Rivnut which seems to do the same as the Hank Nut but rather more cheaply. It seems the underlying technology of the rivet is the same, but Rivnuts are much closer to the pop rivet with which I am sure we are all familiar. Just in case that has passed you by this is what the vendor(s) showed:
Rivnut Picture (500 x 500).jpg
Rivnut Picture (500 x 500).jpg (31.11 KiB) Viewed 36016 times

There are also hand tools to compress the nuts that are offered at a very low price (£8.42 GBP) and with mostly good reviews. I suspect that they are made in China under questionable working conditions so one might or might not get a good one.
Voche Rivnut Tool.jpg
Voche Rivnut Tool.jpg (21.05 KiB) Viewed 36018 times
So, that is a possible alternative for those of us with somewhat lower standards in our making.

Regards

Pete
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Re: Hex Hank Rivet Bushes

Post by marinesteam »

Rivnuts are good but have a high profile (they stick out the back of the sheet pretty far). They are also easy to install using the setting tool. Our goto for low profile installations are Pem nuts https://www.pemnet.com/products/product ... /cls-m4-2/. I haven't installed any myself as we always have our sheet metal vendors do it. Google Pemsetter tooling guide for a pdf which IIRC has drawings for the tooling needed.

Cheers

Ken
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Re: Hex Hank Rivet Bushes

Post by Lopez Mike »

I notice that, in the case of the Rivnut, it protrudes 1 mm from the surface. This may or may not be an issue with your application. Are air leaks a possible problem?

Not to seem like too much of a barbarian but I've had very good luck with simply tack welding a suitable nut on the back side of the inner shell. That is assuming you have easy access to the nut. For what it's worth, you can weld S.S. with ordinary mild steel fusing material like Mig or torch or with what every welding method you are comfortable. The weld, of course, will not be corrosion resistant.

The captive nuts that hold my stack to the cone on my VFT have been there for ten years now. I use short enough screws that very little thread extends beyond the nut. Cuts down on removal struggles.

Mike
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Re: Hex Hank Rivet Bushes

Post by PeteThePen1 »

Thanks for the suggestions MarineSteam and Mike.

I am afraid that welding is not a skill I have ever had the chance to learn. However, the self clinching Pemnuts sound good. I will have a browse over the Festive period and see if they are available in the UK. The application is the boiler casing for the mono-tube boiler that I have been developing although 'developing' is too grand a word to use for copying an original and making tweeks. Most of the effort has gone into learning to use OnShape 3D CAD since the sheet metal laser cut and bend firms here all want STEP files.

Good wishes for Chritmas and the New Year to you all. Let us hope that 2024 is a much better year than 2023.

Pete
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