HELP -- I need to drill a 1 1/8" hole in fiberglass

[Kevin K]

Would I use a
1-1/8" Hole Saw ?
1 1/8" Wood bit ?
1 1/8" Steel drill bit ?
Step bit ?
Will be adding another 12 Volt socket

[Thomas G.]

I'd use the hole saw or the step drill. Cover the area with masking tape first to get a cleaner edge. They make hole saws with finer teeth, which would make a nicer hole.

[Spanke]

I would use the hole saw with the masking tape as Tom suggested. Take it slow and let the tool do the work, you'll get a cleaner hole that way.

Spanke

[Evan Friesen]

I've used a fine-toothed hole saw and I wasn't happy with the amount of strands that got pulled up and gel coat chipping. The thing I was putting in the hole had a flange that covered the rough bits. I did not use masking tape either...that probably would have helped.
I would have liked to use a step-bit as it seems as it would have been 'gentler' and more gradual.

[cpaharley2008]

I used the hole saw to install mine, keep speed slo tho.

[Jim Bennett]

This would work nice and quick, but there would be a bit of fraying on the sides of the hole. You would get a bonus second hole too, maybe for an access hatch on the other side. * * *





* * * Please kids, do not try this at home, this is a job for a professional.




All kidding aside, the hole saw is the way to go. As long as it is sharp, it will work fine. Start slow until you get a good bite. Use a bit of sandpaper to smooth out the glass shards on the edge of the hole when done too.

[steve dunham]

Originally Posted by Thomas G.

I'd use the hole saw or the step drill. Cover the area with masking tape first to get a cleaner edge. They make hole saws with finer teeth, which would make a nicer hole.

Drill the 1/4" pilot hole in forward , run the 1 1/8" hole saw in reverse .
Less chance of having a tooth catch and causing damage . Method works well on steel and aluminum siding

[captsteve2002]

Use the hole saw, and not the butterfly bit. The hole saw cutting through the masking tape will cause less chipping of the gelcoat. Don't use the butterfly bit it will damage the glass, gelcoat, and you will have a rough hole. I haven't used the other tools, but alway had good luck with the hole saw on boats. Be careful not to cut through the interior covering as that won't work well. As others have said, take it slow and don't use a lot of pressure on the hole saw/drill motor as that will case some tearing of the glass strands. It is also not a bad idea to use tape on the interior of where you are drilling to help keep tearing on the inside of the hole to a minium. Good Luck

[Steve L.]

I like the carbide grit hole saws. Failing that, the other Steve's suggestion of running the saw tooth hole saw backwards (after the pilot hole penetrates) is a good one.

When the saw penetrates be prepared for the teeth grabbing any carpeting, if any, that might be glued to the back.

[mary and bob]

I'm sure this won't work in your situation, but if you can clamp a piece of wood to each side of where you are cutting the hole, it helps in making a cleaner cut. Or at least wood on the back side.

[Byron Kinnaman]

I'm quite fond of the Dremel RotoZip for this type of thing. It makes the smoothest cut in fiberglass I've ever seen. To cut a round hole you would have to make the circle and follow it slowly.

I would think that a step bit would be the next best thing.

[cpaharley2008]

Except one little ooops, your hole is now oblong, they cut too easy.

[Kevin K]

I have a side dinette with cabinets above. Thinking about adding the new 12 Volt outlet under the cabinet and between the shelf openings.


Need outlet for my laptop.
I also have a 120 volt outlet on the bench seat. I could add the 12 volt next to it.

Decisions Decisions

[Andrew Gibbens]

Originally Posted by Steve L.

I like the carbide grit hole saws.

Professionally, that's what we used building fiberglass yachts, if only because a toothed hole saw doesn't last long in fiberglass. But if we had a one-off to do, we would buy just a fine-tooth hole saw for economy.

[cpaharley2008]

Kevin,
I believe you have 12v in the oh for the lights, very easy to tap into and install an outlet for 12v, also you may want to switch out the 120v outlet to the newer 120v/usb found at amazon FastMac ACE-7169 U-Socket Standard Duplex Dual Outlet Dual USB, 110V, 15AMP TruePower, White - Amazon.com

[jimmied]

Originally Posted by Kevin K

I have a side dinette with cabinets above. Thinking about adding the new 12 Volt outlet under the cabinet and between the shelf openings.

Attachment 53329
Need outlet for my laptop.
I also have a 120 volt outlet on the bench seat. I could add the 12 volt next to it.
Attachment 53330
Decisions Decisions

Just a suggestion, but I ran a heavy 12 gauge wire to the receptacle as 16 may be a little too light. When I had an old television, in a previous rig, the inverter would keep shutting down, due to a light gauge wire.

[Kevin K]

Thanks for all the GREAT tips.
cpaharley2008 I didn't know they had a outlet like that, I might have to install that also.

[Bob Miller]

I use a 1" hole saw when I want a 1 1/8" hole, they almost always cut a little large and it's a lot easier to file out a little than to add anything back..... Try a trial cut somewhere first.

[Raz]

If you have access to a metal fabrication/ machine shop, a Greenlee punch produces a very clean hole. Raz

[Bob Miller]

I have several well used Greenlee punches and warn others that they will punch a decent hole in molded fiberglass only if they are SHARP.

Any that have punched much metal get dulled tend to crack or craze molded fiberglass. For that reason I don't use mine on fiberglass.