Screws, holes and fibreglass.

spiller

spiller

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On removing panels, half the screws are no longer holding, just sitting there filling the holes into which they no longer bite.

Probably been answered a thousandfold already, but ideas, tips or tricks to restore holes that have become enlarged in fibreglass (ie, equivalent of gluing a couple of marchsticks into oversized holes in wood).

I don't want to increase the screw size because that means replacing all if appearances are to be maintained.

Someone out there must have a magic fix??? !!
 
[ QUOTE ]
equivalent of gluing a couple of marchsticks into oversized holes in wood.

[/ QUOTE ]Sort of answered your own question.... /forums/images/graemlins/smirk.gif
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
Thanks Cliff, but with wood, you have a few mms of depth to get some purchase. With fibreglass, often only 2mm thick, the matches don't work.
 
Self tapping screws are not the correct fastenings for GRP.
Apart from coming loose as you have found, they also damage and split the laminate, allow moisture to enter it, and are not strong, secure, nor safe.
The correct fastenings are bolts with nuts and washers. Washers and nuts can be glassed in on the blind side if there is no access.
Cup washers, preferably with nylon washers under them to spread the load and protect the gelcoat, look neater on the outside, but metal strips are even better, and for fixing heavily loaded items such as stanchions, quarter inch plywood or plastic material plus metal backing plates should be used.
Personally I think it is disgusting that modern tupperware is held together with self tapping screws.
I saw an example hauled into Falmouth after the 1979 Fastnet whose stanchions, and pulpit, unbelievably, had been attached with self tappers, and together with the lifelines had been ripped off and wrapped around the hull. I think I even have a photo of it somewhere.
Boat builders could once be trusted to produce boats which were suitable for purpose.
Sadly, cost and corner cutting has become the norm, and owners now accept panels, even windows held on with self tappers.
 
Chall 32,

Your points noted and well appreciated.

I am actually referring to minor access panels that have about 32 screws holding them in. Nuts and bolts would be overkill, but, nevertheless, I have about 32 holes, of which 25 are oversized and 25 screws play only a cosmetic role.
 
One way you could try is to use a small piece of foam sponge (a foam ear plug is good) and soak it in epoxy and poke through hole. Poke plug a good way in and let epoxy set. Clean up with a sharp chiesel and drill your pilot hole. Good luck. It does work and is not very hard to do, however do use disposable gloves.
 
There are various fixings available from B&Q for plasterboard that would suffice if the panel you need to re-secure is not structural or load bearing.

I used a lot of pop rivets on thin fibreglass in the past, ether ali or you can acquire s/steel food grade rivets but you need to be strong or have a lazytong type gun for the latter.

Darren
 
you can just run a little ARALDITE into the 'thread' in the hole. make sure you let it cure fully before putting the screws back in
 
Try knocking in a plastic raw-plug, if lucky it will be a tight fit and of the right length if not trim off any excess length. A spot of sealent before inserting will reduce any leaking issues.
 
I myself would be fitting a solid wood or plywood backing plate behind the pannel opening so when you screw the screws into their holes they are actually going into wood, and this wood should be bonded in place, or drill and countersink some holes from outside, fit small c/s screws to hold wood in place while pannel is off, then when pannel is screwed back on the screws you use will also hold wood in place.
 
You can buy rubber inserts that are designed for this purpose, called Rawlnuts. They are shown here A top-hat shaped piece of rubber with a nut at the crown end. Drill out the hole until the rawlnut can be pushed in. Then attach your panel with bolts, which pull the rubber towards the blind side of the GRP as you screw them up. The tail lights on my camper van are attached with them, using stainless nuts and bolts.
 
a little blob of gripfill or nomore nails or even silicone is a simple solution. Put the panel in place using all the screws then after it has hardened a little give the previously usless screws a few exrea twists.
 
[ QUOTE ]
On removing panels, half the screws are no longer holding, just sitting there filling the holes into which they no longer bite.

Probably been answered a thousandfold already, but ideas, tips or tricks to restore holes that have become enlarged in fibreglass (ie, equivalent of gluing a couple of marchsticks into oversized holes in wood).

I don't want to increase the screw size because that means replacing all if appearances are to be maintained.

Someone out there must have a magic fix??? !!

[/ QUOTE ]

Now that the "experts" have spat forth ..... let me give you a tip ....

Drill the holes out a little bit further and with a hammer tap into place short suitable plastic rawlpugs ......

Now refit original panel and screws and go home to sleep peaceful in the sure knowledge that all is well ............ without having to undergo major surgery.

/forums/images/graemlins/crazy.gif /forums/images/graemlins/crazy.gif /forums/images/graemlins/crazy.gif /forums/images/graemlins/crazy.gif
 
I find that method doesn't always work. The problem is that the Rawlplug is at its smallest OD at the very top, so after drilling a hole that you can push it through it will rattle about when pressed home. The design of the plug is such that it divides in the tapered section. When the screw is turned in it may grip on the plastic material adjacent to the sheet GRP or it may catch in the divided part further in. Unfortunately this doesn't always happen, meaning that the screw is loose and cannot be tightened. You have then drilled a larger hole for nothing.

I have some very short, square rawlplug-type fittings that were originally made for exactly this purpose but they don't seem to be available now.
 
[ QUOTE ]
I find that method doesn't always work. The problem is that the Rawlplug is at its smallest OD at the very top, so after drilling a hole that you can push it through it will rattle about when pressed home. The design of the plug is such that it divides in the tapered section. When the screw is turned in it may grip on the plastic material adjacent to the sheet GRP or it may catch in the divided part further in. Unfortunately this doesn't always happen, meaning that the screw is loose and cannot be tightened. You have then drilled a larger hole for nothing.

I have some very short, square rawlplug-type fittings that were originally made for exactly this purpose but they don't seem to be available now.

[/ QUOTE ]

Sorry - I was a little lax there ... the ones I mean are very short and more like a ribbed tube - designed to go into underside of chipboard furniture - when the leg screws tear out ! They have no split in and are sized to the screw. You can cut to length as needed.

I've just noticed ... NEW smileys appearing ... is YBW getting snazzy ????
 
IMHO these are worse than Rawlplugs, unless they have a brim on the outside of the hole. You rely on the friction between the plug and the drilled hole but I find that the screw mostly pushes the plug inside and cannot be tightened.
 
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