Our diamond hole saw performed very well on the 1st cut but not so well on the 2nd and 3rd cuts. This only means that the diamond abrasives were lost at the end of the 1st cut.
It is important to note that these diamond hole saws need to be used with effective water cooling.
If you do not use water or if you apply too much pressure, the tip of the hole saw will overheat. The electroplated bond will locally lose strength causing the diamond abrasives to separate.
If you have efficient cooling, 200-300 RPM speed, and mild tool pressure, you can cut 10-20 holes in glass depending on the glass thickness.
Some of our customers are able to drill 30 bottles with one bit.
Diamond hole saw are used for brittle materials such as glass, ceramic, porcelain, granite, etc.
Pilot bits are usually not good for brittle material applications. They tend to make a crack before the hole saw starts working. The crack propagates and ruins the project.
Instead of a pilot bit, our DRILAX sets comes with a tough poly insert with can be used as a guide to hold the diamond hole saw steady.
You only need the insert for the few turns. You can continue free hand once the diamond hole saw makes the initial mark.