D-Bits and taper plug valve seatings

[Tony MartyrParticipant @tonymartyr14488]

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

[Tony MartyrParticipant @tonymartyr14488]

[Author]

Posts