Hi All, The Diamond Core drill worked a treat although I wish I had bought more drills. I only bought one and after the initial bit of fast cutting it became a slow slog as the drill seemed to wear its way through the metal rather than cut it. I used an electric drill which I kept at a fairly low speed and used water with a touch of washing up liquid to lubricate the drill. The ironic bit of the story is, after slowly wearing my way down through the bolt head, when I reckoned that I was almost down to the washer under the bolt head I gave it a tap on the outside with a screw driver and hammer. Although the remains of the head were only hanging on by a thin bit of metal the whole bolt spun free and I took it out using finger power only. This raises another interesting point. I remember years ago the theory that with the right sort of vibration the tightest nut or bolt will loosen off. Bearing in mind how tight this bolt was, using the diamond core drill did I just happen to hit on the right combination of frequency to make the bolt loosen off? I think that this technique could be used to remove broken taps or drills. Mind you the resulting hole will be far larger than the original intended hole but thats better than scrapping a valuable bit of machinery Regards Clif MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.