I know of nobody this side of the Ocean that uses a brad-point drill for drilling wrestplanks and I've never heard of a factory that does. The German suppliers sell special wrestplank drills with a fast spiral. One of these is illustrated in the lower picture, but the ones I have, and prfer have a more acute angle (60°) to the point, the same as the centre drill in the top picture. The way I do it is in three stages: 1. punch the centres 2. drill the pilot hole and leading countersink with a 1/4" or 5/16" centre drill as shown, stopping before the cylindrical shank. 3. drill with the special wrestplank drill. That's it. JD -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100812/7179f4a8/attachment-0001.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: centre_drill.jpg Type: application/octet-stream Size: 11183 bytes Desc: not available URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100812/7179f4a8/attachment-0002.obj> -------------- next part -------------- A non-text attachment was scrubbed... Name: plank_drill.jpg Type: application/octet-stream Size: 21303 bytes Desc: not available URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100812/7179f4a8/attachment-0003.obj>
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