Once in a while a block can separate from the sprue. This can happen due to a variety of reasons, one of them can be if they are stored to close to a heat source, which will melt the glue or loosen it
When you go to mill, as soon as the drill touches the block, it can dislodge it. Most milling machines will or can continue milling an “air ball”. It’s imperative that everyone in the office recognizes the milling sounds made (or not made) when this happens. If your ears are tuned into the milling machine sounds, you can save yourself a lot of time and headache
