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+--- Thread: best fastener for double skin aluminium onto a steel tube (/showthread.php?tid=4737)
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best fastener for double skin aluminium onto a steel tube - JonE - 29-07-2020
The Speedex has a bonnet strap which seems a bit out of character.
The four corners of the bonnet also seem to want holding to the frame on either side, so it keeps the shape.
I've looked at Dzus but it appears that the fixing needs to be in a position where the underlying point is right on a steel tube (frame) under the outer alloy.
I've got some alloy rivnuts but wonder whether the on/off requirements are too much for such a thread.
what would you use that enables a quick release of sorts, but is quite minimalist from the outer view? I'm presuming it's going to need to go through the entire tube, but be relatively thin so not to weaken.
RE: best fastener for double skin aluminium onto a steel tube - Mike Costigan - 29-07-2020
Can you weld or otherwise attach a flange to the tube, and then use these bonnet pins?
https://www.demon-tweeks.com/demon-tweeks-competition-quick-release-steel-bonnet-pins-2005204/?sku=C/CCC01&istCompanyId=a2904180-3a7d-4e56-b876-cf81c9512180&istFeedId=6fbc4b04-fd28-4ce1-8513-835c8f118690&istItemId=wptwrmqlr&istBid=t&gclid=Cj0KCQjwvIT5BRCqARIsAAwwD-TAKgnQ3at2h1klgNt_RYYJ8UlQAE4Ho6VTkXFDYbJtvkedsFux5kUaAlLnEALw_wcB&gclsrc=aw.ds
C-CCC01SBLK_d2.jpg (Size: 66.02 KB / Downloads: 298)
RE: best fastener for double skin aluminium onto a steel tube - Renaud - 29-07-2020
A lot of tricks HERE too Jon.
RE: best fastener for double skin aluminium onto a steel tube - Paul N-M - 29-07-2020
Dzuz Panex may be your best bet as they only need a flat flange to slide over.
RE: best fastener for double skin aluminium onto a steel tube - Stuart Giles - 29-07-2020
You could use rubber bonnet catches like these:
https://www.lsengineers.co.uk/bonnet-catch-small-rubber.html
they do a larger version as well.
RE: best fastener for double skin aluminium onto a steel tube - JonE - 29-07-2020
Thanks all. I want to get away from external clutter, otherwise the rubber ones would be perfect.
The issue is the sensible point of attachment is OVER a frame tube, so the Panex wouldnt work.
Mike's bonnet catches would if they went through the frame, in which case they feel too big. They would also be encumbered by a lock nut on the top of the lower panel as well as behind the tube.
Perhaps I can devise something smaller diameter which just has a thin 'head' to it under the eye, so it can just be fastened/locked from a nut to the rear. If there are two either side, 4 total, the bonnet pin spec could be reduced a bit??
If not, these perhaps are the smallest.. https://www.carbuilder.com/uk/stainless-steel-hidden-retainer-mini-over-centre-fasteners
RE: best fastener for double skin aluminium onto a steel tube - Mike Costigan - 29-07-2020
Can you just make up simple 'bent-wire' clips from threaded rod that you just twist under the tubes?
bonnet fastening.png (Size: 16.28 KB / Downloads: 244)
RE: best fastener for double skin aluminium onto a steel tube - David.H - 29-07-2020
There are stud versions of Rivnuts called ....Rivstuds ! 0r there used to be when we sold them! Otherwise you could use say - M6x15 into the tube ( or put an M6 bolt into a Rivnut in the far side of the tube, or even a bolt across the tube with a half nut to hold it & support the bonnet) and then retain the bonnet with e.g. a wing nut or a washer with an R pin into a hole in the bolt.
Many ways of skinning this cat! The over centre clip looks the neatest to avoid catching things (skin) on if you can fit it on.....
RE: best fastener for double skin aluminium onto a steel tube - JonE - 29-07-2020
Mike - yes that would work but the whole point is to make it look as subtle as possible.
David - that starts to make sense! The bonnet doesn't weigh very much so as long as it is safe from getting breeze under front edge, then I'll look up these rivstuds and R pins which I havent heard of.
M6 would be fine... I was even wondering about M5 size.
I'm now thinking, a top hat-like thing which would screw down over the retained bolt... like a collar with a button on top. In fact, a stronger wider version of what a rivnut looks like!
Bound to be something, I just don't know what I'm looking for yet...
ok, how about a "rubber nut" from the rivnut range, in the tube from the rear?
And just a knurled thumbscrew in from the front, perhaps with fibre or nylon washer against the aluminium?
RE: best fastener for double skin aluminium onto a steel tube - Duncan Grimmond - 29-07-2020
I almost fitted these to the boot lid of my current project but decided they were too new looking. However they are very good. All you can see is the button and the escutcheon and they release and catch easily and quickly. The bearer for the ball-end stud obtrudes into the free space but if you have room for them I'd recommend them