hopkimf

My Feedback: (56)

Maybe everyone but me already knows this.

I always seemed to get a ragged hole with my hand held electric drill. The bit would break out and advance rapidly on the flutes making an erratic hole. A controlled feed with a drill press would help. If I had the right unit, I would use it.

The procedure that works best for me is to first drill a small pilot hole. Next I drill the finished diameter. But this time, I run the hand held drill backwards. It produces a round hole without any tendency to pull the drill out of my hand.

tashley

My Feedback: (9)

The ragged hole is formed when the tip of the drill "breaks out". I've never tried the reversed drilling method but it sounds worthy of trying. One thing that will help is use a wooden block held tight to the back of where the drill will exit.

tuwood

yep, i do that too and another thing that really works well if you can get access to both sides easily is to clamp a piece of wood on both sides of what your drilling. This helps keep the drill bit from tearing through the fiberglass & making a mess.

tashley

My Feedback: (9)

Step drills work super on fiberglass cowls and any other thin medium also such as sheet aluminum, plastic, plywood, etc...

Rcpilot

My Feedback: (78)

Use a Dremel or other moto tool.

For small holes 1/8" or less, you can put the bit in the dremel and use that. The high speed of the dremel helps to prevent cracking.

Most dremels have an 1/8" collet. So, if you need to put a 1/16" bit in there, just wrap the bit with tape untill it's big enough to provide a snug fit when chucked up in the dremel.

For cutting large holes or trimming around cylinder heads and mufflers I use the 1/2" sanding drum. Or they make a 1/4" sanding drum.

To start a hole with a sanding drum, just put the sand paper drum on the rubber attachment, but leave it floating off the end about 1/8" or so. I mean, don't put the drum all the way on the rubber part. Leave a bit hanging off the end.

By leaving some of the drum hanging off the end, it acts like a hollow drill bit. Perfect for starting a hole in the cowl.

Use masking tape on the cowl to help keep from chipping the edges. Draw pen marks on the masking tape for your outline.

Take a popsicle stick and glue a piece of 80 or 100 grit sand paper to the popsicle stick. Trim the paper to fit after the glue dries. When you get the cowl openings close with the dremel, use the stick to finish it up and make sure the edges are straight and clean.

Kwigen

A drill press probably would not make much difference. There is usually a little slack in the feed and the bit's twist will pull it into the material. The step drill is a better way to go. For small holes you can try heating an awl and melting your way through. A little stinky but it makes a smooth hole with no tendencies to crack.

Flyboy Dave

My Feedback: (21)

I've had good luck by simply taping the glass with masking tape, and drilling.

I know what you mean....straight drilling of fiberglass can result in the figure
"8" pattern. [X(]

FBD.

Kmot

My Feedback: (24)

You can also buy special built dedicated fiberglass drill bits.

tommy s

My Feedback: (55)

Rcpilet is correct,the only way to drill or open a hole in fiberglass without ever splitting
the fiberglass or making an irregular hole is with a Dremel tool and a sanding drum or
one of the Dremel specialty bits which are available a Home Depot if your LHS doesn't
have them. A regular drill bit is just asking for problems on fiberglass.

tommy s

Gringo Flyer

My Feedback: (18)

I always use a dowel wrapped with a piece of sandpaper to get a super smooth finish at the end. For me the dremel cuts smooth but my hand is not steady enough to cut perfect. A little touch up with the dowel gets everything crisp and straight.

horace315

My Feedback: (15)

i use the tape and dremel with the tapered stone,then after i get the hole big enough ill use the sanding drum or whatever other burring tool i have in my dremel kit as needed.you do need something solid behind what you are drilling almost all the time to get a good hole like a piece of wood.

scratchonly

I bought a 1/8 inch carbide ceramic cutting bit for rotary tools at home depot. Stays in my dremel flex cable hanging over my workbench. Cuts almost anything but ferrous metal.
Try it you will like it.

TLH101

My Feedback: (90)

Dremel tapered grinding stone work great for drilling fiberglass cowls. just go deeper to get a larger hole, and the edge of the hole stays nice and smooth. Good for round hole up to about 3/8", and then you can actually make the hole larger, using it like a drum sander.

ballgunner

My Feedback: (1)

Black & Decker makes a power screwdriver that turns much slower than a Dremel Moto Tool. Drilling with a Dremel is more like melting your way through. Micro Mark has a chuck on a hex mount that is identical to the Dremel chuck. It will fit into the power screwdriver. B & D also has a set of drills from 1/16 to 1/4 that fit the screwdriver. Any drilling I have to do in plastic is done with the B&D power screwdriver. You can get a 6.0 volt one from Home Depot. The standard 3.2 volt is only $19.95 from Wal Mart. The chuck from Micro Mark is about $10.00. Sears hads a power screwdriver but it is much more expensive. Probably intended for professional work. The B&D probably turns less than 500 RPM.

Stew99

I have a set of carbide cutters I got from Micro Mark. There are 3 sizes all with 1/8 shanks so they will fit the standard Dremel chuck. They can be used to drill a hole and then enlarge it as necessary. I disagree with ballgunner about using a lower rpm. It's the slow speed of a drill that lets the bit catch a produce a ragged hole. I use my Dremel on the highest speed. For large cutouts I will rough out the opening with the carbide bit and finish up with a small sanding drum. This method produces a lot of fiberglass dust so use a mask and a vacuum.

SST

My Feedback: (2)

I have one of the cheapie drill presses from Harbor freight, and use the highest speed with an appropriately sized end mill. Regular flat-end will do a good job, but ball-nose will be a bit easier to use. Beautiful, clean holes...