490,749. Boring-bar machines. NITSCHMANN, A., NITSCHMANN, F., and JESCHOR, P., (trading as NITSCHMANN & SOHNE, W.). Feb. 19, 1937, Nos. 4966 and 4967. Convention dates, Sept. 9, 1936 and Nov. 2, 1936. [A Specification was laid open to inspection under. Sect. 91 of the Acts, Aug. 20, 1937.] [Class 83 (iii)] In a method of boring the main and cam-shaft &c. bearings of internalcombustion engine crank-cases, centring rings are placed on the boring- bar for co-operation with the bearing housings in the work so that the latter will be moved automatically into its correct position when it is brought into contact with the bar. In one form the machine comprises a bed 1 on which are mounted the boring-head 2, two standards 4, 4<1> for supporting the boring-bar 5 and two vertically-adjustable work supports 9, 9<1>. The boring-bar is connected by a flexible coupling 3 to the head 2 and is mounted in split bearings 10, Fig. 2, on the standards, adjusted by hand-operated screws 13. Brackets' 8 attached to the standards carry split bearings c in which a rod 6 is adjustably secured, this rod carrying an arm 14, Fig. 3, provided with caliper legs 18<1>, 18<11> for centring and adjusting the diameter of cut of the boring-bar 5. An adjustable stop pin 16 for the arm 14 is provided. The leg 18<11> is adjustable on a slide 18 to which the leg 181 is attached,' and which is adjusted in lugs a, b on the bracket by means of a slidable pin 21 and a graduated dial 19 movable along a slideway 20. A cutter is provided for each bearing on the work and the arm 14 may be moved opposite each in turn and clamped at 7. The bearings 10 are mounted in spherical seats in the standards 4, 4<1> to relieve the boring-bar from strain. The worksupports 9 comprise a base 24, Fig. 6, carrying vertical posts 25 on which a cross-bar 26 is vertically adjustable by racks and pinions 28, 281 a coarse hand adjustment being effected by means of a crank at 30 or a fine adjustment by means of a hand-operated worm drive 32. One bar 26 has a convex surface for engaging one end of the work 33 and the other carries a yoke 41 secured by bolts 42 and provided with a ball joint 40 on which is mounted a plunger 39 entering a cylinder bore in the other end of the work. Bolts 34 and clamping plates 35 secure the work vertically whilst brackets 36 and adjusting screws 37 on the bars 26 prevent lateral movement of the work. The work is positioned by means of stepped cylindrical collars on the boring bar 5 engaging the bearing recesses therein and then clamped, after which the cutters are adjusted by the caliper 18 and the bearing bushes inserted in the crank-case 33 for boring. The boring- bar has a number of cutter apertures spaced axially at close intervals so that a cutter may be inserted adjacent each bearing in the work, but all will not start cutting simultaneously. The work may be supported by a single vertically adjustable table mounted on a tilting bearing. For boring connecting-rod bearings a bracket may be used having a boss entering the bearing 10 in the standard 4 and a flange carrying a vertically adjustable pin for supporting the small end of the rod. Lateral screws on the flange position the big end in line with a boring tool carried by the spindle of the head 2. In a modified machine the work 33 is carried by supports 9, 91, Fig. 13, which are laterally but not vertically adjustable, and the boring- bar 5 is carried by spherically seated bearings 10 on vertically adjustable brackets 63, 63<1> which are movable on the horizontally adjustable standards 4, 41 by screws 90 operated by hand wheels 89. The headstock 2 is vertically adjustable on a pillar 2<1> by means of a screw 66 and hand wheel 67 and is located with its spindle in alignment with the boring-bar through a lever pivoted to the bracket 631 engaging a lug or recess on the headstock. Extensions of the brackets 63, 631 are provided with bearings c for a rod 6 carrying a toolsetting device similar to that shown in Fig. 3. Scales are provided on the standards 4, 41 to facilitate the vertical adjustment of the brackets 63, 63<1> and stops may be provided for ensuring the return of the brackets to an original position after the insertion of a new work-piece 33. One of the supports 9, 9<1> consists of a plate 80, Fig. 17, mounted by means of a balljoint 40 on a base 77 which is laterally adjustable by means of a hand-operated screw 78. The work 33 is secured to the plate 80 by a plate and bolt 81 and is adjusted and secured laterally by brackets 83 and screws 84. The other work-support has a laterally-adjustable member 86, Fig. 19, making line contact therewith, or alternatively having two point supports. Stepped cylindrical centring rings are used on the boring-bar 5 to co-operate with the bearings in the work to set the latter, and the bearings 10 are split to enable the bar to be removed after setting in order to allow the bearing linings which are to be bored being inserted in the work. A flexible coupling connects the bar 5 to the head 2.