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connecting rod 008.jpg
479 viewsThese blanks will be used for the new connecting rod in the Quickdraw engine.Jim Allen
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523 viewsThese connecting rod blanks are precisely machined to fit on the same holding fixture. The alloy used is AISI S-7 shock resistant tool steel. After proper hardening in oil & tempering, the connecting rod will have a tensile strength of 315,000 p/si.; a yield strength of 210,000p/si.; a hardness of 58 Rockwell C; & a C-notch Charpy impact test over 224 ft. lb. Jim Allen
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726 viewsThe holding fixture with upper & lower pins removed. Notice the steel sleeves at both the upper & lower pin holes for the locating pins to sit in.Jim Allen
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504 viewsThe bottom of the holding fixture has holes to locate both the upper & lower end of the connecting rod for milling the round eyes of both. This fixture uses the same bolt hole pattern at both ends when mounted to the rotary table. The sides of the fixture are parallel to the center axis of the holding fixture holes allowing easy alignment at 0 deg.Jim Allen
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715 viewsA side view showing both locating pins. The hole dimensions & locatoions in the blanks must fit the pins in the fixture.Jim Allen
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558 viewsA side view which shows the connecting rod blank sitting on the bored locating pins. Screws pass through each pin to hold the blank firmly in place for machining. Jim Allen
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636 viewsThis is the connecting rod blank fastened to the holding fixture for profile machining of all surfaces.Jim Allen
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810 viewsTop view of the connecting rod showing the area where the I-beam is milled with a .1875 ball nose end mill. The milled groove is opened .007 each side of center to give a very smooth finish.Jim Allen
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822 viewsSide view of the connecting rod mounted on the fixture after all milling is completed. All machined edges on the connecting rods are smoothed. After tempering all connecting rods are sand blasted.Jim Allen
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1118 viewsThe "I"-beam part of a completed connecting rod is .282 wide X .156 thick. The radius at the junction of the I-beam & the upper or lower holes is .8125 (1.625 dia. end mill). This end mill profiles the entire outside of the rod. A .1875 ball nosed mill forms the center section of the I-beam which is .031 thick in the center. The wrist pin hole is .250 ID X .360 OD. The crank pin hole is .4538 ID X .625 OD. The undercut on the outside of the big end is .031 deep X .156 wide & it also has a radius on the inside corner. The center distance of the two holes is 1.741. After hardening (1760 deg f; quench in oil) the S-7 rods are double tempered at 400 deg f., giving a tensile strength of 315,000 lbs/square in, a yield strength of 210,000 lbs/square in, at 58 Rc & a 1 in Charpy V test of over 224 ft lb.Jim Allen
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