464 



Popular Science Muuthly 



diameter of the horing-bar illustrated. 

 A three-arm spider tastinp; having a 

 substantial boss was bored out to be an 

 easy runnintj fit on the intermediate 

 diameter of the boring-bar. This was 

 securely held against the cylinder base- 

 flange by means of clamping straps. It 

 is held away from the base-Hange by 

 tubular spacers while the clamping 

 straps were separated at the top by 



hardwood spacer 



blocks. The boring 

 tool was a special 

 iron casting having 

 an inserted cutting 

 tool made of tool 

 steel. The cutter 

 was held in place l)y 

 a set-.screw and was 

 inserted in a drill 

 hole made to re- 

 ceive it. The bor- 

 ing tool was .se- 

 curely clamped to 

 the intermediate 

 portion of the bor- 

 ing-bar by a set-screw, 

 was made to smooth 



cylinder and the boring-bar guide se- 

 curely clam[)ed thereto, it will be appar- 

 ent that the boring-bar center line had 

 to coincide with that of the cylinder. 



The cutting tool is set for the desired 

 depth of cut, leaving about 1/64 in. of 

 stock on a side to be removed with the 

 reamer. The lathe is started on the back 

 gears and the cylinder-block is moved 

 back slowly to meet the cutting tool by 

 moving the tool 



UAMPiHG SfAAPS 

 5PAC£R BLOCKS 

 CrUNDCK CASTING ^^^ 



ij 



SORING BAD OUlOe 

 aORiNG BAR 



Boring-Bar Guide and Method of Fasten- 

 ing It with Clamps 



A special reamer 

 the cylinder after 

 the boring cut was completed. This was 

 made of a tool steel disk having sixteen 

 cutting teeth milled on it and forced on 

 a cast-iron bushing which was a good 

 fit on the boring-bar. The boring-bar 

 was machined from a piece of machinery 

 steel \]A. in. in diameter. 



In assembling the parts, the first step 

 was to put the centering disk into the 

 cylinder interior and then locate the 

 cylinder carriers and boring-bar guides. 

 The centering disk was an easy push fit 

 in the cylinder interior and, of course, 

 held the boring-bar in the center. When 

 the cylinder carrier was clanipcd to the 

 base flange of the cylinder-block, and 

 the centering disk was backed out and 

 its place taken by the boring tool, 

 the cut started straight. Absolute 

 parallelism of the boring-bar with the 

 cylinder walls was secured by i)utling 

 the centering disk at the head end of 

 the cylinder and then adjusting thi' 

 centering fi.xture screwed into the core 

 jjrint hole so that the guide ring would 

 supfKjrl the head end of the cylinder 

 properly on the small diameter of the 

 l)()ring-bar. After the centering disk 

 had been moved to the open i-nd of the 



to finish the job. 



post carnage with 

 the hand feed. As 

 soon as the cut is 

 started the power 

 feed is adjustecl for 

 a fine cut and the 

 regular feed screw 

 is used to bring the 

 cylinder casting 

 down. Only one 

 cut is taken with 

 thecutting tool, this 

 being afterwards re- 

 moved and the 

 reamer substituted 

 As the cylinder-block 

 floats on the boring-bar and as the guide 

 members must be accurately located 

 initially by the centering disk provided, 

 the new bore nmst lie true to size and the 

 walls parallel to the center line of the 

 cylinder. 



It took about ten hours to bore and 

 ream four cylinders or one cylinder- 

 block. The setting up and locating took 

 about two hours while the cutting occu- 

 pied the remainder of the time. The 

 cyliiuicr flange rested on the ways of the 

 lathe, this resisting the tendency of the 

 cutting tool to turn the cylinder casting 

 about the boring-bar. The weight of the 

 casting was enough to prevent any 

 N'ibration or chattering due to movement 

 of the cylinders. In doing a job of this 

 kind it is essential that the cylinder be 

 accurately located on the boring-bar. 

 Till' guiile bearings should be thoroughly 

 oiled and should lie a goixl sliding 

 fit on the arbor without ha\lng any 

 vertical movement or shake. Tlu' boring 

 tool should bi' carefully sharpened and it 

 is absolutely essential th.it it be fed in 

 slowly, so that only a fine cut will be 

 taken. There is no necessity of blocking 

 up the cylinder casting as this is ade- 

 (|iiately supjxMted.- John B.Maynard. 



