Drilling a clean 3/4 hole

[DewRonInc]

What do I do to not chip fiberglass while drilling a 19mm hole. Needs to be clean and no chips

[tdt91]

Start with the drill in reverse and get a clean hole through the gel coat. Then put it in forward to drill the rest of the way through.

[billnorman1]

Interesting. Perhaps a pilot hole and then a tapered ream. Practice on something other than your boat.

[mvpsteve]

As stated above, drill bit in reverse, put masking tape over where the hole is going to be, center punch the starting spot.

[RazorCat]

Two layers of painters tape applied perpendicular to each other over the area to be drilled. I prefer a sharp holesaw to a drill bit when drilling fiberglass. In the past two months I’ve had to drill three 1-1/4” holes and a 6-1/2” hole for wiring and access at the bow. They all came out smooth on the outside with minimal splintering on the inside. I’ve tried the reverse method and got no better results. I prefer to apply tape as mentioned, set the drill on high speed, start the hole with the pilot bit, and then drill the finish hole with holesaw using steady, even pressure. A sanding block or sandpaper can be used to smooth the back edge if necessary.

[fishnfireman]

Two layers of painters tape applied perpendicular to each other over the area to be drilled. I prefer a sharp holesaw to a drill bit when drilling fiberglass. In the past two months I’ve had to drill three 1-1/4” holes and a 6-1/2” hole for wiring and access at the bow. They all came out smooth on the outside with minimal splintering on the inside. I’ve tried the reverse method and got no better results. I prefer to apply tape as mentioned, set the drill on high speed, start the hole with the pilot bit, and then drill the finish hole with holesaw using steady, even pressure. A sanding block or sandpaper can be used to smooth the back edge if necessary.

Much better results.

[XingEyeballs]

Masking tape and a sharp hole saw instead of a drill bit, like stated, run in reverse through the gel. If it’s in an area that’s not really thick I just leave the drill in reverse with light pressure.

[Mark Perry]

No way I would use a center punch on a fiberglass boat either.

[CatFan]

Two layers of painters tape applied perpendicular to each other over the area to be drilled. I prefer a sharp holesaw to a drill bit when drilling fiberglass. In the past two months I’ve had to drill three 1-1/4” holes and a 6-1/2” hole for wiring and access at the bow. They all came out smooth on the outside with minimal splintering on the inside. I’ve tried the reverse method and got no better results. I prefer to apply tape as mentioned, set the drill on high speed, start the hole with the pilot bit, and then drill the finish hole with holesaw using steady, even pressure. A sanding block or sandpaper can be used to smooth the back edge if necessary.

My experience is that hole saws like to drill oversized a little, but are less likely to chip glass. I use a hole saw when size isn’t super important, and a spade bit when whatever covers the hole is close to the size of the hole. Had to use Marine Tex and paint on an installation years ago to help hide the hole, though I’d used a spade bit on that one. It was someone else’s boat, and I was upset as hell over it, but he never noticed it and asked me to do the installation on his next two boats, so I guess it worked out.

Makes me nervous to drill glass, because it can chip even when you are very careful. It’s a huge relief when I see that clean ring through the gel coat.

[BOATS]

However you do it, whatever bit, put tape down and drill slow through that.

[DewRonInc]

I have a 3/4 carbide cutter. Will that work

[SteezMacQueen]

When I cut/drilled my skeeter for power poles and a charger socket, I used a new Milwaukee step bit and a Freud hole saw. As noted above, masking tape and drill in reverse to get through the top layer of gel coat are common ways to prevent surface chips. Even then, It ain’t a 100% sure fire way to get through. It always has a possibility to chip. It’s just the way it is.

go slowly and use an air compressor and blow tool to keep the blade clean and cool<<<that helps a lot.

[RazorCat]

My experience is that hole saws like to drill oversized a little, but are less likely to chip glass. I use a hole saw when size isn’t super important, and a spade bit when whatever covers the hole is close to the size of the hole. Had to use Marine Tex and paint on an installation years ago to help hide the hole, though I’d used a spade bit on that one. It was someone else’s boat, and I was upset as hell over it, but he never noticed it and asked me to do the installation on his next two boats, so I guess it worked out.

Makes me nervous to drill glass, because it can chip even when you are very careful. It’s a huge relief when I see that clean ring through the gel coat.

Agreed that a holesaw can tend to produce an oversized hole. Using a higher speed for drilling is the best solution I’ve found. Mark the hole on the tape, start the pilot hole without going all the way thru the glass, and then fully commit. With the bit in position bring the drill up to full speed, insert the pilot bit, and then drill the hole with one straight, steady push. I have used that method successfully on dozens of holes. It still didn’t prepare for the emotional distress I experienced the day I had to drill the 6.5” access hole under my TM pedal. But, The hole came out perfectly using the method described above. The access panel fit snuggly in the hole.
A holesaw is much more likely to wallow the hole out if you take too long to get thru the material you’re drilling.

[CatFan]

Agreed that a holesaw can tend to produce an oversized hole. Using a higher speed for drilling is the best solution I’ve found. Mark the hole on the tape, start the pilot hole without going all the way thru the glass, and then fully commit. With the bit in position bring the drill up to full speed, insert the pilot bit, and then drill the hole with one straight, steady push. I have used that method successfully on dozens of holes. It still didn’t prepare for the emotional distress I experienced the day I had to drill the 6.5” access hole under my TM pedal. But, The hole came out perfectly using the method described above. The access panel fit snuggly in the hole.
A holesaw is much more likely to wallow the hole out if you take too long to get thru the material you’re drilling.

But drilling slowly is the natural response to the nerves that happen when you start to drill a 6” hole in your shiny new boat!

[CatFan]

Agreed that a holesaw can tend to produce an oversized hole. Using a higher speed for drilling is the best solution I’ve found. Mark the hole on the tape, start the pilot hole without going all the way thru the glass, and then fully commit. With the bit in position bring the drill up to full speed, insert the pilot bit, and then drill the hole with one straight, steady push. I have used that method successfully on dozens of holes. It still didn’t prepare for the emotional distress I experienced the day I had to drill the 6.5” access hole under my TM pedal. But, The hole came out perfectly using the method described above. The access panel fit snuggly in the hole.
A holesaw is much more likely to wallow the hole out if you take too long to get thru the material you’re drilling.

But drilling slowly is the natural response to the nerves that happen when you start to drill a 6” hole in your shiny new boat!

[DewRonInc]

When I cut/drilled my skeeter for power poles and a charger socket, I used a new Milwaukee step bit and a Freud hole saw. As noted above, masking tape and drill in reverse to get through the top layer of gel coat are common ways to prevent surface chips. Even then, It ain’t a 100% sure fire way to get through. It always has a possibility to chip. It’s just the way it is.

go slowly and use an air compressor and blow tool to keep the blade clean and cool<<<that helps a lot.

That is why I thought a carbide cutter, very sharp might be better, I can cut through 1/2 plate with this bit

[DewRonInc]

I also have a press cut tool, also very Sharpe, it only allows exact size zero spreading of hole size

[DewRonInc]

A step bit and a Dremel might be better

[DewRonInc]

Problem this is for a switch, very small lip

[DewRonInc]

Actually have to cut two holes , guess I am just gonna have to just do it