Tony Martyr | 12/02/2010 13:20:24 |
![]() 226 forum posts 45 photos | In spite of faithfully following 'the books' I have never made a 100% success of using a home-made D-bit to form a flat bottomed hole that would form a text-book valve seating. In my present case I am making a steam regulator body of a simple Martin Evans design. My D-bit all hardened and correctly tempered did not seem to cult the (gun-metal) drilled hole bottom but rather scuff it. In all other cases where a flat bottom hole is required I have managed to find a milling cutter or slot drill of the desired diameter but not in this case. Since the taper of the regulator spindle is sharper than the bottom of the drilled hole I can't see why my nasty semi flat hole gives a better seal than the cleanly drilled one - but I bet you can! Tony |
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