Granite Drill Bits vs. Glass Drill Bits and Pilot Bits

We usually only address one issue or question with each post, but this week we were asked two very good questions in the same e-mail. So, we thought that we would take a shot at answering both questions.

1. What’s the difference between Granite Drill Bits and Glass Drill Bit?

Glass drill bits are electroplated, while drill bits for granite and concrete are sintered. With glass bits, the diamonds are electroplated to the surface of a stainless steel blank, using a nickel bonding material. The diamonds are just on the surface.

Granite drill bits are sintered. The diamonds are mixed in a softer metal. As this metal wears away, new diamonds are constantly being exposed.

Glass drill bits will drill granite and concrete, but will wear out very quickly, maybe before the first hole is drilled.

Granite drill bits will drill glass, but they leave a hole with very rough edges. With most applications, additional smoothing and polishing would probably be necessary and the "blowout" on the back side of the glass is more common and more extensive.

2.) Shouldn’t these ”diamond core bits” have a pilot bit?

We've seen a few diamond core bits with pilot bits, but it's simply a marketing issue, because most people think that the bits should have a pilot bit, so one manufacturer puts a pilot bit in. Most manufacturers do not.

The pilot bit would have to be centered in the same way that the core bit has to be centered: Using a notched piece of scrap wood, plastic etc.,  or used in a drill press or started at a 45 degree angle. If you have to do that with the pilot bit, you might as well just do it with the diamond core bit.

In addition, the pilot bits will also wear out much more quickly and will have to be replaced more often. In our blog post from April 4th, we tackled the question about using pointed (pilot) bits: "Do Pointed Drill Bits Work Better?"

For more answers to your questions, you can always download a free copy of “How to Drill Glass, Tile and Stone." Click here for your FREE copy.

Can I Drill Sea Glass?

I’ve collected tons of sea glass. Now I want to do something with it.

Can I drill holes in it and make jewelry?

This is one of the most common questions that we get and it’s really a “twofer.” The second question that always comes with it is, “which drill bit do I use to drill holes in my sea glass?”

Two great questions! Two very popular questions! Unfortunately, with no right answer.

It’s a matter of personal preference. We recommend that you use a drill bit with a rounded end, either a round ball or a round end cylinder.  

The rounded (spherical) end puts twice as many diamonds in contact with the glass as a flat end cylinder.  

If I could find my 9^th grade Geometry teacher, I would like to tell him that those formulas for finding the area of a circle and a sphere came in handy. Took a long time but I finally did use them. Who would have thought?

The two most popular bits for drilling sea glass are the 1/16” and 1/20” bits. The holes they drill are a good size for almost all beading wires, fishing line, jump rings and earring findings. The 1/20” is just a little smaller. Both will fit in a drill, drill press, Dremel tool or rotary tool.  

You can see them both at the Drill Sea Glass section of our website. They’re also both included in the ”Beginner’s Sea Glass Set.”

So, no right answer but two answers that are a lot more popular for drilling sea glass. If you want more information about drilling sea glass and sea shells, you can download a copy of "How to Drill Sea Glass" from our website.

Can I Drill Glass Without Using Water?

Yes, you can drill glass without using water, but you probably shouldn’t. I agree, setting up a water bath or a spray bottle can be a pain and it can make drilling messier.

You can drill “dry” with any diamond drill bit. But, the bit will burn up - Guaranteed!

Diamonds are incredibly hard. Much harder than the glass, tile or stone that you’re drilling. However, the friction created by drilling heats up the glass or tile and the diamond bit. So hot that they can actually turn red and glow.

We’ve had customers tell us that they use WD-40, brake fluid, mineral oil, antifreeze and kerosene as coolant/lubricants. All are interesting choices but none work as well as water with a drop or two of dishwashing soap. Not enough soap to make it sudsy, but just enough to break the surface tension of the water.  

Water is also the easiest to clean up afterwards. Have you ever tried getting WD-40 out of a glass block or a wine bottle? You don’t want to!

Using a water bath or spray will pay off. You trade 30 seconds of extra drilling time for a bit that will last two or three times as long. It’s a bargain. You don’t want your drill bits to end up like the picture above.

You can download a free copy of “How to Drill Glass, Tile and Stone” by clicking here.