Self-centering jaw chuck

[4. A jaw chuck as in claim 3 and wherein:

• a. said leaf means comprises a pair of leaf members associated with each of
• said master jaws.] 5. A jaw chuck as in claim [4] 1 and wherein:
• a. each of said leaf members of each pair is substantially U-shaped with each leg of each leaf member of each pair being parallel to the other legs
• of said pair. 6. A jaw chuck as in claim 5 and wherein:
• a. said body member is circular, and
• b. each leg of each leaf member of each pair is chordally disposed with
• respect to said body member. 7. A jaw chuck as in claim [2] 1 and wherein:
• a. said axially reciprocable cam means comprises a draw plug axially reciprocable in said body member,
• b. a cam plate member secured to each of said master jaws on an inner surface thereof,
• c. a recess in each of said master jaws adjacent said cam plate member,
• d. an elongate slot in each of said cam plate members,
• e. a cam head in each of said recesses between said cam plate member and said master jaw,
• f. bolt means passing through said slot for securing said cam head to said draw plug,
• g. whereby upon reciprocation of said draw plug, said cam head acts on said
• cam plate to radially reciprocate said cam plate and said master jaw. 8. A jaw chuck as in claim 7 and including:
• a. a bushing around said bolt means and positioned in said slot. 9. A jaw chuck as in claim [2] 1 and including:
• a. spacer means having a thickness slightly greater than the thickness of said master jaws for maintaining an operating clearance between said work gripping members and said fixed portions and between said radially
• reciprocable portion and said body member. 10. A jaw chuck as in claim 9 and wherein:
• a. said spacer means comprises a plurality of bolts positioned in spaces between said master jaws,
• b. each of said bolts having an enlarged head portion, a shank portion, and a thread portion,
• c. a bushing member having a thickness slightly greater than the thickness of said master jaws and positioned around said shank portion,
• d. said thread portion threadedly engaging said body member, and
• e. recesses formed in said work gripping members to provide working
• clearance around said head portion. 11. A jaw chuck as in claim 6 and wherein:
• a. said leaf members, said fixed portions and said radially reciprocable
• portions are all defined by slots provided in said master jaws. 12. A jaw chuck as in claim 11 and including:
• a. three of said master jaws. 13. A master jaw for use in a reciprocating jaw chuck comprising:
• a. an element having a configuration generally of a truncated sector,
• b. said element being symmetrical,
• c. a first pair of slots of substantially equal length extending chordally inwardly from [said arc] the outer periphery of said truncated sector ,
• d. a second pair of slots of substantially equal length extending into said element substantially perpendicularly to said first slots and having terminal portions extending outwardly substantially parallel to said first slots,
• e. said slots dividing said element into two spaced portions attachable to a chuck body and an intermediate portion movable with respect to said
• spaced portions for supporting a work gripping jaw. 14. A master jaw as in claim 13 and wherein:
• a. said truncated sector is formed by two radii, an included arc, and a
• chord intersecting said radii. 15. A master jaw as in claim 14 and wherein:
• a. said element is symmetrical with respect to a radial line bisecting the
• angle between said two radii. 16. A master jaw as in claim 15 and wherein:
• a. said first pair of slots are substantially parallel to said chord. 17. A master jaw as in claim 16 and wherein:
• a. said second pair of slots are substantially parallel to said radial line of symmetry.