PerthWA

Best way to drill into fiberglass????

17 posts in this topic

Hi

I have a 2005 235 Ssi and have recently purchased an EPIRB that I would like to install on the lower part of the dash under the circuit breaker board.

The unit comes in a bracket that needs to be mounted on the boat with four small screws.

I have never drilled into fiberglass before and would appreciate the wisdom of some of you old salts on how best to do it without chipping the top layer?

Appreciate any guidance you might have.

Thank you

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Start with an 1/8 bit and run the drill in reverse. That will keep it from chipping. Increase several times until the desired diameter is achieved while drilling in REVERSE only.

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I've wondered this answer myself.  I tried to drill a mounting bracket for my GPS and took a $%^$% of fiberglass out.  :(

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It also helps to put masking tape over the area to be drilled. Keeps the gelcoat from chipping. 

brick

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I do the MI3 way. Then some times shift to fastest speed & light pressure .  F G  is ALWAYS A RISK. Glass gets harder with age sometimes. Especially if too much hardener was used originally.   OH WELL.

  Running a table saw or band saw blade backwards also works when cutting brittle sheets of any plastic type of material.

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I just drill with a proper sized bit, don't care about minor cracking. Never really have any to be honest though.

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Start with a small bit and work your way up. Remember too, glass is harder than wood. Stainless is softer than normal steel screws. If the screws starts to become very hard when installing, stop. Chances are you will snap the screw! Ether re-drill the hole a little bigger or back the screw out and in a few times. Re-drilling works out better depending on how much is needed.  

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9 hours ago, brick said:

It also helps to put masking tape over the area to be drilled. Keeps the gelcoat from chipping. 

brick

Yep!   And if the bit slips to you have protection.

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"IF" you can reach both sides of the fiberglass where you want to drill you can clamp a piece of 1/4" aluminum and drill through it to make your hole. The clamped metal keeps the drill bit straight and true in it's contact with the fiberglass and will make a clean hole. As said earlier debur or countersink the hole to prevent stress cracking after the fact.

Drill guides are common in manufacturing jigs and fixtures to ensure accurate and clean holes.

Joe

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All good tips n tricks. I can add that heating the area with  heat gun  prior to drilling also helps avoid cracking the gelcoat finish. Also after you drill if you can smear a bit of epoxy around the top bottom and edges of the holes drilled it will seal any mico cracking which could become spider cracks over time.

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Hi

Thank you all for the feedback and guidance...it is very much appreciated.

I will give it a go later in the week and let you know how it goes.

Thank you very much.

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10 hours ago, IndyChap said:

Carefully....  DSC000022.jpg

+1

i have cut speaker holes several times, and I am always nervous. So far I have been lucky...

brick

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