Epoxy a nut to the inside of GRP

simonfraser

simonfraser

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I have a GRP locker top with a hole cut in
a plastic frame has been sikkaflexed on top
a plastic lid is on top of this

the lid has been screwed down with self tappers into the GRP
the holes in the GRP are worn

thinking of inserting these from below into the GRP and epoxying the fixings in
then using machine screws through the lid and frame to tighten it down

what else can I fix on the inside to get some decent traction ?
it needs to be undone at times
 
simonfraser said:
I have a GRP locker top with a hole cut in
a plastic frame has been sikkaflexed on top
a plastic lid is on top of this

the lid has been screwed down with self tappers into the GRP
the holes in the GRP are worn

thinking of inserting these from below into the GRP and epoxying the fixings in
then using machine screws through the lid and frame to tighten it down

what else can I fix on the inside to get some decent traction ?
it needs to be undone at times
Click to expand...
Bigheads?

fasteners - big head - Female Hex Nuts
 
Last edited:
+2 for Big Heads - they are designed precisely for this application. The rivnuts you link are not, the flange on the head is designed to hold it in place whilst the nut is expanded (like a rivet, hence the tern rivet nut), it'll likely pull through in your application.

If it's for light loads (e.g instrument panels or similar) rubber well nuts are good.
 
Praxinoscope said:
The only problem I can see with Big Heads is that they are mild steel not stainless.
Click to expand...
". bigHeads are manufactured from mild steel for general applications and in 316S11 grade stainless steel to cope with aggressive environments typically in off-shore or marine applications. bigHead Bonding Fasteners bond well in materials suc"
 
Another possible, and much cheaper, solution for SimonFraser might be to glue some hardwood battens underneath the locker lid with epoxy or CT1 (or suchlike) along the line of the screwholes and simply screw down through the GRP into them.

Or, simply drill through and use nuts and bolts and penny washers instead of self-tappers.
 
I prefer to use self-tapping inserts. For example, those with an M5 internal thread usually have an M10 external thread. After inserting the insert, which cuts a thread in the grp, I then remove it and coat the thread that it has cut with epoxy before re-installing it. There are blind versions available which effectively prevent water leaking through the internal threads. Very useful for deck fittings where self tappers may have been used previously. They’re very cost effective. See “shop4fasteners“ for example.
Mike
 
MonniotC said:
At that price it's worth buying an entry-level mig or arc welder and making your own. And you'd have a useful toy afterwards.
Click to expand...

I'm not sure how many you would have to make to get a payback, but a welder, gas, material, mask, gloves, a jig to make them consistent and straight and consumables... and it would need to be MIG, ideally TIG for SS, arc would blow a hole in something that small. I can't see the value, other than having a new tool and some re-usable skills (which, if that is the reason - i'm in ? (y) )

I just buy mine online, they tick the "just works" box & the quality remains long after i've forgotten the price ;)
 
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