chouchou
Member
How do you refix fastening in GRP that have been pulled out from GRP. I want to reuse same holes however I cannot just increase size of screw.
GRP Fastening
- Thread starter chouchou
- Start date
john_morris_uk
Well-Known Member
Clean out hole and loose material. Fill with epoxy. Drill new pilot hole.
Are you sure it wouldn't be better to through bolt the item? Most fixings on GRP should be through bolted: I can't think of many thinks that will survive just being screwed in place.
Are you sure it wouldn't be better to through bolt the item? Most fixings on GRP should be through bolted: I can't think of many thinks that will survive just being screwed in place.
snowleopard
Well-Known Member
You may find the best solution is a BigHead. Unfortunately the manufacturers only supply a minimum of 100 of any type so You'd need to find a retailer who will sell them individually.
(I have a lot of M6 x 25mm male ones left over. They cost me around a quid each. I might be persuaded to part with one or two)
(I have a lot of M6 x 25mm male ones left over. They cost me around a quid each. I might be persuaded to part with one or two)
homa
Well-Known Member
I just had a thought..
If you cannot get access behind to fix with a bolt...
Why can't you use a cavity wall fixing? Most are nylon and therefore will not rust...Just a thought..
If you cannot get access behind to fix with a bolt...
Why can't you use a cavity wall fixing? Most are nylon and therefore will not rust...Just a thought..
Malcb
Well-Known Member
[ QUOTE ]
I can't think of many thinks that will survive just being screwed in place.
[/ QUOTE ]
I've had two that I've had to fill with epoxy, re-pilot drill etc. Fixing my windows, they are not bolted through, with a sealant as well and refixing a stud for the spray hood.
I can't think of many thinks that will survive just being screwed in place.
[/ QUOTE ]
I've had two that I've had to fill with epoxy, re-pilot drill etc. Fixing my windows, they are not bolted through, with a sealant as well and refixing a stud for the spray hood.
john_morris_uk
Well-Known Member
I am not sure what point you are making here. If your windows are screwed into place and not bolted it doesn't mean that the boat builder's method was right... I am still sure that there only a very few things on a boat that can be fixed by screwing them into GRP.
I have had a good think and have found a couple on my boat.
1. The winch handle pockets.
2. The blinds in the heads and their catches (screwed from the inside).
I have had a good think and have found a couple on my boat.
1. The winch handle pockets.
2. The blinds in the heads and their catches (screwed from the inside).
ShipsWoofy
Well-Known Member
I have occasionally for none heavy type items wrapped some string around the threads which becomes like a wall plug as the string bunches when you screw it in. You will be surprised maybe how tight you can tighten using this method.
Do not think insulation tape will work the same, it doesn't.
For heavier work, you could buy a thread insert, this is the preferred method for screwing into dissimilar metals, but will also do the job you are looking for. They come as heli coils or small tubes that screw into a bigger hole leaving you an M3 thread or similar from a 5mm hole. This would make a far superior job as it would mean not using self tappers which are always a bit of a compromise.
The other way would be to fill the holes with epoxy and re-drill the pilot holes which should allow you to go back to the original self tappers, if you are patient and allow the epoxy to cure properly, it should be pretty good as a long term solution. We all try to finish the job too quickly hence my rushing point, to quick and it may just pull out again.
Hope this gives you a few ideas.
Do not think insulation tape will work the same, it doesn't.
For heavier work, you could buy a thread insert, this is the preferred method for screwing into dissimilar metals, but will also do the job you are looking for. They come as heli coils or small tubes that screw into a bigger hole leaving you an M3 thread or similar from a 5mm hole. This would make a far superior job as it would mean not using self tappers which are always a bit of a compromise.
The other way would be to fill the holes with epoxy and re-drill the pilot holes which should allow you to go back to the original self tappers, if you are patient and allow the epoxy to cure properly, it should be pretty good as a long term solution. We all try to finish the job too quickly hence my rushing point, to quick and it may just pull out again.
Hope this gives you a few ideas.
fdmarsden
Well-Known Member
I have fitted halyard rope clutches by the following method where there was no access to the inner
Drill a hole about one inch diameter through the outer skin.
remove the balsa core down to the inner skin and undercut the balsa about 1/4 inch.
Make a solid grp plug one inch diameter, and fix in position with either epoxy with thickener (colloidial slica) or polyester with reinforcement, not just unfilled resin.
Plastic Padding Glass Fibre Paste from Halfords is suitable, only problem is that it is green.
File flush with the surface
Then drill and tap the size you need.
This works when the load is parallel to the surface.
Have not and will not try when the load is at a significant angle to the surface.
Drill a hole about one inch diameter through the outer skin.
remove the balsa core down to the inner skin and undercut the balsa about 1/4 inch.
Make a solid grp plug one inch diameter, and fix in position with either epoxy with thickener (colloidial slica) or polyester with reinforcement, not just unfilled resin.
Plastic Padding Glass Fibre Paste from Halfords is suitable, only problem is that it is green.
File flush with the surface
Then drill and tap the size you need.
This works when the load is parallel to the surface.
Have not and will not try when the load is at a significant angle to the surface.
PCUK
Well-Known Member
FIlling the hole with SIkaflex and refitting the original screws works well with lightly stressed items.
