Drilling Into Fiberglass To Mount A Graph

[BassThumb]

I just tried to mount a new graph near the console of my Stratos, and after drilling pilot holes into it about 1/4 of an inch deep, there seems to be a metal plate or something in there that's not allowing me to go any deeper. This is right next to the holes from the other graph that was on there, and they went through cleanly.

Any suggestions?

[Catt]

Drill completely through & mount with bolts/screws & nuts

[B-Dozer]

Be thankful there is a re enforcement you can use. Do what Catt says.

[Sfritr]

Sounds like there are a few back braces from your other unit. Catt is correct. Use bolts it will work better in the long run

[BassThumb]

Thanks guys. There doesn't appear to be any braces in there from the other unit. I can stick my finger in the 1" hole and feel around. Nuts and bolts sound like a good idea. I have been using wood screws with a shot of adhesive silicone in the pilot hole to attach other things, like a recessed petal and battery charger. Funny thing is, I never had any probelms cutting/drilling into the glass before, but this top cap is another story. It's way tougher than the rest of the boat. I drained my cordless drill's battery trying to make one hole through the metal yesterday.

[Fishing Rhino]

Thanks guys. There doesn't appear to be any braces in there from the other unit. I can stick my finger in the 1" hole and feel around. Nuts and bolts sound like a good idea. I have been using wood screws with a shot of adhesive silicone in the pilot hole to attach other things, like a recessed petal and battery charger. Funny thing is, I never had any probelms cutting/drilling into the glass before, but this top cap is another story. It's way tougher than the rest of the boat. I drained out my cordless drill's battery trying to make one hole through the metal yesterday.

Wood screws are fine for wood. But, the threaded area is tapered, and as soon as it loosens in the slightest, its holding power is severely comporomised. I prefer using stainless steel, pan head, Phillips head, sheet metal screws. Other than at the point, they are not tapered. Should they loosen due to vibration or whatever, they do not lose holding power like wood screws will.

When mounting in fiberglass or other plastics, the tapered threads on a wood screw are problematic. Drill a hole large enough for the smaller diameter of the screw can result in stress cracks since the screw acts like a wedge as it is tightened. Drill if to receive the thicker threaded section and the smaller section of the tapered threads provides little holding power. They work well in wood because wood can compress which makes for a very tight connection.

You can get them in flat head, or oval head for countersunk, flush mount applications. For mounting brackets, I prefer the oval head, simply because I like the look better.

[BassThumb]

Wood screws are fine for wood. But, the threaded area is tapered, and as soon as it loosens in the slightest, its holding power is severely comporomised. I prefer using stainless steel, pan head, Phillips head, sheet metal screws. Other than at the point, they are not tapered. Should they loosen due to vibration or whatever, they do not lose holding power like wood screws will.

When mounting in fiberglass or other plastics, the tapered threads on a wood screw are problematic. Drill a hole large enough for the smaller diameter of the screw can result in stress cracks since the screw acts like a wedge as it is tightened. Drill if to receive the thicker threaded section and the smaller section of the tapered threads provides little holding power. They work well in wood because wood can compress which makes for a very tight connection.

You can get them in flat head, or oval head for countersunk, flush mount applications. For mounting brackets, I prefer the oval head, simply because I like the look better.

Good points. Thanks.

[Catt]

Screws/bolts with nuts & washers will out hold any screw period, plus when they work loose they can be easily retightened.

[K_Mac]

A drop of Locktite when using bolts and nuts will help keep things from loosening up. Just my $.02.

[slonezp]

Pick up a cobalt or titanium bit to drill thru the metal. Many metal bits are also "low speed" bits and drill better with the drill on low rather than hi speed.

[Fishing Rhino]

A drop of Locktite when using bolts and nuts will help keep things from loosening up. Just my $.02.

When I mount anything like this on my boat I use the aircraft type lock nuts with the nylon inserts.

By the way, there are many places where you can only use a screw. Be it for transducers, temperature sensors, weather heads, cable/wire clamps, etc., where it would be very difficult if not impossible to use a bolt and nut.

[K_Mac]

Good idea Rhino.

I have SS sheet metal screws in a variety of places in my boat also.

[BassThumb]

I ended up getting through that sucker, I just needed a new bit. My gold Dewalt bit must be damaged or worm out because it wasn't doing squat to the metal sheets that are layered in the glass.