Riveting pcb holes - engineering type input sought!

[mekanik]

Sorry can't see your logic there, even if you use the hollow rivet method i think you will find that they protrude from the board also, and forgive me if i am wrong but all the pcb assemblies i have seen the wires from the components also protrude through the board with a solder fillet.
But i am only a klanky so what do i know.
Good luck on whatever you decide.
Regards
Mike

[HankMcSpank]

Whilst not the same project at all, this guy has the same challenge & you can therefore get a flavour...

http://www.cycfi.com/2014/08/neo-base-boards/

...mine will be a similar shaped pcb to that - and one of these covers goes atop ..... http://www.themusiczoo.com/product/1...-Covers-White/ )

The logic of using the rivet is that it probably sits proud less than 1mm on the top surface (ok, so I said in my former post that the enclosure butts up against the pcb.....indeed it does, but at the perimeter only, there's probably about 1mm of 'head' clearance where the holes are)

[mekanik]

I know you don't have a lathe so this is probably not going to help but i think the best solution would be a top hat type of insert drilled and taped 3mm the flange could be 0.5mm thick so minimal protrusion, clearance hole in the board to locate it while soldering top hat in place.
Regards
Mike

[mekanik]

http://www.theinsertcompany.com/bras...or_plastic.php

[HankMcSpank]

http://www.theinsertcompany.com/bras...or_plastic.php

thanks but they looks broadly similar to the nuts I referred to in my opening post...

http://www.rapidonline.com/mechanica...4658e0d0b4ee75

(actually the ones at Rapid Online have smaller hole 4.2mm vs 4.6mm for M3)

like I say, the spec for those things suggest my pcb holes are going to be too close to the edge of the board.

[magicniner]

Have you considered M3 RivNuts?
I've set M6 Riv-Nuts in Polycarbonate, Fibreglass and ABS by using a washer on the back and crimping tight enough to hold but not tight enough to damage, the hole in the base material is drilled clearance and it's the tension of the Riv-Nut between head and washer that holds by friction on the surfaces.

I used washers cut from Polyurethane sheet on both sides of the Polycarbonate and Fibreglass to prevent wear with vibration, rain and road dirt but I suspect you won't have those issues ;-)
Regards,
Nick

[mekanik]

thanks but they looks broadly similar to the nuts I referred to in my opening post..

Was just looking for the makings really, it's a simple job to chuck these on a mandrel in the lathe,remove the serations and even skim the flange OD if that's too large.
Regards
Mike

[magicniner]

Was just looking for the makings really, it's a simple job to chuck these on a mandrel in the lathe,remove the serations and even skim the flange OD if that's too large.

You don't need to skim the serrations, you need to adjust the drilled hole size to suit the material you're using to avoid splitting, you'll still have significant resistance to turning from the mechanical fit, add a 2-part adhesive for adequate retention and you're sorted.

thanks but they looks broadly similar to the nuts I referred to in my opening post..

If you use a backing washer, as I stated, the hollow section spreads and partially collapses outside the washer and doesn't spread in the substrate, no stress on the hole, just compression of the board, so no splitting.
I guess that's similar ;-)

[magicniner]

I have the mandrel for the setting tool.

Whilst you can buy and use a Riv-Nut setting tool all you need is a flat steel bar with a hole through it and roughed up a bit on the side presented to the Riv-Nut head, preventing slipping when setting.
Use a bolt or bit of threaded bar through the flat bar and fully engaged with the Riv-Nut threads.
With lubed washers & well lubed nut on top, tighten nut whilst ensuring the bolt doesn't turn and set the Riv-Nut to the tension or height of your choice.
I use 60% Moly paste for the lube as it gives the best possible friction reduction and thus translates as much torque as possible into tension.

- Nick

[mekanik]

My idea was to solder the insert, removing the serations means you can have a smaller hole in the board so the board is stronger. the inserts could be machined to practically any size you want.
Regards
Mike