# Drilling Holes through gelcoat?



## MariettaMike (Jun 14, 2012)

I need to expand a 3/4" hole up to 1" in order to get the cable for my new depthfinder through the console.

I have a paddle bit and a hole saw in 1". I am currently planning to drill a 1" hole through a sheet of aluminum and then screw it down over the existing hole to act as an outside pilot.

The question is which bit is better for drilling through the gelcoat without chipping? Does putting masking tape over the spot help minimize the chipping?

Any help would be appreciatted.


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## cutrunner (Jun 8, 2010)

One inch hole saw and blue masking tape.


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## ASB73 (Jan 27, 2012)

I have used bits like this for my drill and worked it around the hole to make it bigger 
http://www.toolking.com/dremel-407-1-2-inch-drum-sander-bit?CAWELAID=482610143&cagpspn=pla&gclid=CK2Zjv_m1rICFQcGnQodNX8AmA


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## jms (Apr 21, 2011)

> I need to expand a 3/4" hole up to 1" in order to get the cable for my new depthfinder through the console.
> 
> I have a paddle bit and a hole saw in 1". I am currently planning to drill a 1" hole through a sheet of aluminum and then screw it down over the existing hole to act as an outside pilot.
> 
> ...



stepped bit - or "unibit"

trying to use the hole saw is asking for trouble...

fyi:
blue masking tape is useless to prevent chipping...
way to drill through gel without chipping is to run the drill in reverse,till you're through the gel,then switch the drill direction - doing this,the gel will never chip...


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## DuckNut (Apr 3, 2009)

Once again I agree with kreepa


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## cutrunner (Jun 8, 2010)

[/quote]




fyi:
blue masking tape is useless to prevent chipping...
way to drill through gel without chipping is to run the drill in reverse,till you're through the gel,then switch the drill direction - doing this,the gel will never chip...[/quote]
I didnt know that. Thanks for the tip!

Yea later i read back and realized what i had wrote about the whole saw.
It would work, but it would be a real pita and you would have to be very careful.
Is the surface your drilling thin enough for a step bit to work?


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## MariettaMike (Jun 14, 2012)

Got r' dun!

Found my 1-1/8" Unibit in the drill case right where I left it. Drilled the 3/4" hole out until the 1" hole saw would get in there and finished it off with that. No tape. Unibits are worth the price. The next hole I drill with it will be 1-1/8" for the Marinco trolling motor receptacle right through the front deck.

Getting the holes for the mounting bracket screws the right size was actually the hardest part.

Thanks for the advice.


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## jms (Apr 21, 2011)

i do this stuff every day...


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