Captive nuts and fiberglass
Nov 7, 2014 18:04:21 GMT -5
Post by 81pumagtc on Nov 7, 2014 18:04:21 GMT -5
I was faced with a dilemma with the Pig of Plastic. I had a number of trim pieces that were attached to the fiberglass with wood or sheet metal screws. These are often overtightened, and as a result, become unusable.
One of the other side effects was that they caused splits in the fiberglass, which made them again unusable.
What I decided to do is to glue in a captive nut, and then use the correct size machine screw, which was was a 4-40 (very small) screw.
The first photo shows the door with the original hogged-out holes.
The second photo shows those holes reamed to a tight fit.
The third photo shows the captive (or T) nuts in place. It is virtually impossible to get this size nut for anything but wood, so I cut the prongs off and ground the remaining part of the tab off and flat. I glued them in place with JB Weld.
Here it is with the piece attached to the body. I won't ever have this happen again, and there is no chance of anything splitting, since there is no longer any strain on the fiberglass.
A good rule of thumb is that if it is a structural part under load, you drill through the fiberglass, and use a screw or a bolt, and a large washer on the other side.
If it is a trim piece with very little load, this procedure works very will. If the screw is a larger size, usually #6 or larger, you can also use a wellnut, which is rubber, and expands when you tighten it, as well.
Never use a sheet metal screw, or wood screw, because it will almost always fail
Thought this might be of use for the tub buggy or rail guy out there.
Dave Riedle
One of the other side effects was that they caused splits in the fiberglass, which made them again unusable.
What I decided to do is to glue in a captive nut, and then use the correct size machine screw, which was was a 4-40 (very small) screw.
The first photo shows the door with the original hogged-out holes.
The second photo shows those holes reamed to a tight fit.
The third photo shows the captive (or T) nuts in place. It is virtually impossible to get this size nut for anything but wood, so I cut the prongs off and ground the remaining part of the tab off and flat. I glued them in place with JB Weld.
Here it is with the piece attached to the body. I won't ever have this happen again, and there is no chance of anything splitting, since there is no longer any strain on the fiberglass.
A good rule of thumb is that if it is a structural part under load, you drill through the fiberglass, and use a screw or a bolt, and a large washer on the other side.
If it is a trim piece with very little load, this procedure works very will. If the screw is a larger size, usually #6 or larger, you can also use a wellnut, which is rubber, and expands when you tighten it, as well.
Never use a sheet metal screw, or wood screw, because it will almost always fail
Thought this might be of use for the tub buggy or rail guy out there.
Dave Riedle