Captive nut fibreglass help

[MrChips]

Morning all! Hoping for a bit of advice from anyone with fibreglass experience.

I previously had repaired with the same captive nut just with filler but this has all but worked itself loose. This is mostly hidden from view so doesn't need to be the most visually appealing repair but as a minimum it needs to stop the issue getting worse.

Here's the culprit:



So.... how's best to repair this and ensure the captive nut remains supported??

[Skyedriver]

No real strength in ordinary filler. Would suggest maybe the "hairy bodge" stuff resin with strands in it, but you'll need to get a better "key" to the body than what you have at the moment.
Alternative maybe is to weld the nut to a steel plate, with a hole in it large enough for the bolt to pass through and "pop" rivet that to the body.

[Alan_D350]

Could you use rivet nuts, possibly in conjunction with a flat plate for support?

[tvrolet]

You need to weld the nut on to a longer 'strip' of metal so there's some 'purchase', and then glass the nut/strip in. When I rebuilt the Tuscan I welded the nuts on to a small lengths of metal mesh to give even more purchase. A nut alone is so near-as-dammit round there's precious little to stop it from turning. If the nut is on a strip of metal then there doesn't need to be much strength in the glass/filler to hold it.

I know you can also buy 'captive nuts' with sort of prongs on them - but I just made my own. But you need something more than a nut to stop it turning.

[phillpot]

tvrolet said:

I know you can also buy 'captive nuts' with sort of prongs on them

Something like this and, as already suggested, P40 filler or similar (definitely not ordinary car filler).

[valhalla]

Hi. I used to use a company called 'The Big head bolt fastener company'. Though that was ten years ago. good luck. Dave

[valhalla]

I've just checked, and they are still going. By the way,regarding sticking the big head bolt on, you need davids isopon p40, not p38. You can get both from Halfrauds. You need the one with the fibreglass strands in it. its usually a red hairy paste.

[Dollyman1850]

MrChips said:

Morning all! Hoping for a bit of advice from anyone with fibreglass experience.

I previously had repaired with the same captive nut just with filler but this has all but worked itself loose. This is mostly hidden from view so doesn't need to be the most visually appealing repair but as a minimum it needs to stop the issue getting worse.

Here's the culprit:



So.... how's best to repair this and ensure the captive nut remains supported??

Just make a rectangular plate that can be glassed in which will sit on the junction between the horizontal and vertical panel. Tack weld the bolt to it and then glass it in that way it will not be able to turn when you are tightening and slackening the nut.
N.

[bomb]

http://www.memfast.co.uk/shop/Vprod2.asp?cat=22560...

Try something like these 'rubber nuts'. May work if the hole is tidied up and redrilled.

[RobXjcoupe]

Rather than weld the nut to a plate or mesh, drill and tap a thicker piece of steel or stainless depending on what is being secured and then glass that in position? You could use galvanised steel say 5-6mm thick and rebate it like an interior timber door hinge then use additional counter sunk fixings to hold in place along with a bit of p40 behind the plate for extra security. Could save re-painting the repaired area also.
Just an idea

[GT6k]

Bighead fasteners are the way to go, they are easily available retail and ebay and they include stainless grades

http://www.hall-fast.com/fasteners-small-component...

[Oilchange]

If it was me and I'm very much a bodger, I'd use that square captive nut thing above and mix some epoxy filler but also chop up some carbon fibre into unequal length strands and work the hairy mixture into the part. Looks dark grey when mixed in.
Make sure you have a good 'key' i.e. The surfaces are rough and jagged, gives the resin something to grab onto.
I did this with a few small jobs and I am surprised how strong the smal amount of filler is especially when reinforced with fibre. Wouldn't use gf mind, carbon only (or possibly Kevlar ) as it's super stiff and it really doesn't take much. Epic stuff.

Nb you can't use ordinary scissors to cut it, have to use proper shears, especial Kevlar. Mail me if you want a few small samples I can send in the post...