Jewelers, beading and lapidary enthusiasts, and those that work with sea glass have a common problem: How to make a hole in their material, be it stone, precious or semiprecious gems, or glass.
I have worked with beach stones for about 12 years. They come in different hardness measured on a 1-10 Mohs’ scale. The quarzites are hard (7 on the Mohs scale) and the sedimentary or sand stones are much softer (about 3-5 on the Mohs scale) and therefore easier to drill. We use a Dremel drill. Take a look at the comments to this post about different models of Dremel drills. We use cylinder drill bits that are coated with diamond dust (simply called diamond drill bits). I buy them in bulk because we use so many. I am out of bits again and I just scoured the web for suppliers. This post is about how to choose a supplier! Drill bits come in very different quality, so you want to choose carefully.
First, lets consider the different types of bits. There are 1) cylinder bits, 2) twisted bits, 3) shank bits, 4) core bits, 5) crinkled core bits, 6) cintered core bits. If you are not sure what this means you can check out pictures of these bits at Dad’s Rock Shop. I have tried choices 1-4. Considering the cost, I still prefer the simple cylinder bits or the twisted bits. They are much cheaper. Most sources have a variety of sizes to offer. And you can buy in bulk. They work for really hard stones and they work with glass. In terms of how long they last before they are totally dulled up, it’s your technique which is most important: drill slowly, under water to keep everything cool and with a relatively slow rpm (<2000). Drill even more carefully and without exerting much pressure if you are making a hole in glass.
So, once again I have decided to go with cylinder bits and I want diameters of 1-2 mm. I usually order large quantities, say 300 – 1000 bits. I did a google search for ‘1 mm diamond drill bits’. Here is what I got. The prices are per drill bit.
Dad’s Rock Shop $3.50 (no discount for large quantities)
Lasco Diamond Products $1.75 (1.5mm Diamond drill bits only)
By The Bay Treasures $2.30 (min 50 bits)
Delta One Lapidary $1.85 (min 12 bits)
Twisted bits on Ebay $0.35 (20 bits)
Thunderbird Supply Co. $1.32 (min 30 bits)
Covington Engineering $1.00 (min 50 bits)
Daniel Lopacki $0.95 (min 100 bits)
I read every web site in detail and looked at the “about” section. That tells me whether the seller has first hand experience with drilling stones. I have previously bought drill bits (and other stuff) from Dad’s Rock Shop. They are good quality, but their current prices are not competitive. I have bought poor quality bits too, but not from any of the suppliers mentioned above. I was somewhat interested in the drill bits from Bay Treasures because these are clearly lapidary enthusiasts and concerned with quality products. However, I think I am going to go with Daniel Lopacki. His prices are very competitive if you buy in bulk. And the website includes great tips for drillers. They know how to do it and have done it themselves and quality bits are a concern for this seller too. As you can see, you can get bargains on Ebay. I have had variable success with these bits depending on the vendor. But check out the comments below, because Seth from fans4pc managed to change my mind on his diamond bits which are both well priced and good quality.