item #9. The front jaw shall be integral or attached to the sliding member. The
face of the front jaw shall remain parallel to the face of the back jaw in any
position of travel.
5. The sliding member shall be round. It shall have a smooth machined or cold
rolled finish. The member shall slide in the body with smooth action without
binding at any point throughout the full range of travel. Backlash in either
direction shall not exceed a maximum of one turn of one revolution of the screw.
A collar or other means shall be provided to prevent the screw form coming out
of the sliding member.
6. The vise screw shall be of steel not less than 60,000 psi yield and 80,000 psi
tensile strength. One end of the screw shall have a steel or cast iron head of
adequate size which shall be an integral part of the screw, welded to the screw,
or otherwise securely attached in a permanent manner. The head shall be
provided with a hole to receive the screw handle. The screw shall engage the full
length of the threaded bearing of the body when the jaw is at the maximum
opening.
7. The nut an integral part of the body shall be of malleable iron, threaded to
engage the thread of the screw. It shall fit properly in the body so that it is in
alignment with the screw and there is no binding of the screw in the nut when the
jaws of the vise are opened.
8. The screw handle shall be a straight; round steel bar with means provided at end
to prevent complete disengagement and shall slide freely in the hole of the screw
head.
9. The jaw facings shall be of hard plastic (Nylon), tool steel or mild steel, milled, or
otherwise machined parallel with part of the face that is applied to the castings.
Replaceable hard plastic (Nylon) jaw facings and hard steel jaw facings are
supplied as smooth facings.
10. This tool shall be marked in a plain and permanent manner with the
manufacturer’s name or trademark of such known character that the source of
manufacture may be readily determined.
Figure 3: Yost Model 2503
