733,183. Linear-dimension gauges. JOHNSON, P. W., JOHNSON, S. G., and JOHNSON, C. V., [trading as JOHNSON GAGE CO.]. Oct. 1, 1952 [Nov. 21, 1951], No. 24626/52. Class 106 (2). A linear dimension gauge comprises cooperating gauging means for supporting a test part in its gauging position at a plurality of points, each spaced less than 180 degrees from the next, around the periphery of the test part, the co-operating gauging means being capable of relative movement in a manner permitting the test part to be inserted therebetween; at least one of the gauging elements comprising a rotatable roller adapted to be rotated and to impart rotation to the supported test part; and an indicator responsive to the movement of the co-operating gauging means. In Fig. 1, two rollers or studs 13 and 14 are carried by a frame 11 movable about a pivot 12 to permit a test part T to be inserted between said members 13 and 14 and a co-operating stud or roller 19. The stud or roller 19 is mounted in a frame 20 pivoted at 22 and its movements are indicated by a dial gauge 28. At least one of the members 13, 14 and 19 is a roller that may be turned directly by hand to turn the test body T. For gauging screw threads the members 13, 14 and 19 have gauging ridges. Fig. 5 is a plan view of Fig. 1 with additional means for determining the concentricity or eccentricity of one or more exterior portions or surfaces T<SP>2</SP> of the test body with respect to its,main part T<SP>1</SP>. The arrangement comprises a base 52 having an upstanding wall 51. Pivoted to the wall 51 on a shaft 53 is the arrangement illustrated in Fig. 1, the angular relationship of the assembly with respect to the base 52 being adjustable. A second dial gauge 55 is arranged to bear against a plain cylindrical surface S of the test part between the ends T<SP>1</SP> and T<SP>2</SP>. By rotating the roller 19 the test piece T<SP>1</SP> is rotated and any eccentricity or concentricity of the surface S with respect to the end T<SP>1</SP> is then determined by the second dial gauge 55. The gauge arrangement may also test the concentricity or eccentricity of a second threaded portion T<SP>2</SP> with respect to a first threaded portion T<SP>1</SP> by means of a dial gauge 66 mounted on a frame 59 angularly adjustable on a pivot 60 projecting from the wall 51. This second gauging frame 59 carries an axially movable roller 61 having a single thread engaging ridge 62, the roller 61 being mounted on a member 63 pivoted to the frame 59 at 64. The dial gauge engages the pivoted member 63. Again, 'by rotating the roller 19, say, the eccentricity or concentricity of the portion T<SP>2</SP> is determined by the dial gauge 66. Fig. 7 shows a construction for gauging the squareness of a shoulder H of a test part relatively to surface or thread T<SP>1</SP>. A second indicator 55 is mounted to engage the opposite point on the shoulder. As the test part is rotated while supported in gauging position by the gauging means 13, 14, 19 the test part moves axially as it is turned so that the pointer readings of the indicators 55 increase therewith. If the increase is the same for both indicators upon half a turn of the screw, the shoulder is square with respect to the thread. Fig. 9 shows a construction for testing the concentricity or eccentricity between an exterior thread or surface and an internal thread or surface of a test part T. The internal gauging means is a pin 78 on a frame 79 pivoted at 12. The frame 79 replaces the frame 11 of Fig. 1 or Fig. 5 for inserting the test part T upon the gauging means 78 and to swing it into gauging position to contact the co-operating gauging means or roller 19. When the test part T is turned by turning the roller 19 the concentricity or eccentricity between the internal and external surfaces may be ascertained by the dial gauge 28.