Beam compass

Claim 2

A trammel head adapted for concentric slidable mounting upon a scale, comprising a trammel body containing an opening for receiving a scale; and means for releasably locking said trammel body to said scale, comprising a yoke member having a transverse poRtion extending longitudinally completely through said opening, and a pair of parallel leg portions each of which is integral at one end with opposite ends of said transverse portion, respectively, said leg portions being slidably received in parallel-opposed grooves contained in said trammel body, respectively, and screw means cooperating with the other ends of said leg portions for effecting coplanar displacement of said yoke member in a locking direction to effect frictional locking engagement between said transverse portion and said scale.

Claim 3

A trammel head as defined in claim 1, wherein said yoke member is generally U-shaped and includes adjacent the extremities of said leg portions on the adjacent surfaces thereof inwardly directed projection means adapted to cooperate with the external surfaces of said body member to limit the extent of movement of said yoke member in the locking direction.

Claim 4

A trammel head as defined in claim 2, wherein the opening contained in the trammel body is generally triangular, and further wherein the lateral surface of the transverse portion of said yoke member remote from said trammel body is rounded for locking cooperation within a corresponding longitudinal groove contained between two apices of a triangular scale.

Claim 5

A trammel head as defined in claim 2, wherein said screw means comprises a screw member coplanar with both said trammel body and said yoke member, said screw member being connected at one end with said trammel body and extending outwardly from the external surface thereof parallel with and arranged between said leg portions, and a nut member threadably connected with said screw member and arranged for engagement with the extremities of said leg portions to displace said yoke member in the locking direction.

Claim 6

A trammel head as defined in claim 4, wherein said trammel body is generally triangular and includes external surfaces generally parallel with the corresponding wall surfaces of said triangular opening.

Claim 7

A trammel head assembly as defined in claim 5, wherein said trammel body includes scribe means contained in the plane of and extending outwardly from one apex portion of said body, and further wherein said yoke means, said screw member and said scribe means are contained in a vertical central plane that extends midway between the other two apices of said trammel body.

Claim 8

Trammel apparatus including, in combination, a triangular scale including in each of the three faces thereof a groove extending longitudinally substantially the full length thereof; a trammel head mounted for sliding movement on said scale, said head including a triangular body containing a triangular opening corresponding with the cross-sectional configuration of and slidably receiving said scale; and means for locking said trammel head to said scale, comprising a yoke having a transverse portion extending longitudinally through said opening, and a pair of leg portions integral with the ends of said transverse portion and slidably received in corresponding parallel grooves contained in the ends of said body, respectively, and screw means connected with said body for cooperation with said leg portions to displace said yoke in a direction to force said transverse yoke portion into function-locked engagement with the corresponding groove is said scale.

Claim 9

Trammel apparatus including, in combination, a triangular scale including in each of the three faces thereof a groove extending longitudinally substantially the full length thereof; a trammel head mounted for sliding movement on said scale, said head including a triangular body containing a triangular opening corresponding with the cross-sectional configuration of and slidably receiving said scale; and means for locking said trammel head to said scale, comprising a yoke having a transverse portion extending longitudinally through said opening, and a pair of leg portions integral with the ends of said transverse portion and slidably received in corresponding parallel grooves contained in the ends of said body, respectively, and screw means connected with said body for cooperation with said leg portions to displace said yoke in a direction to force said transverse yoke portion into function-locked engagement with the corresponding groove is said scale.