. Canadian machinery and metalworking (January-June 1919). iles a real lack of small appliancesOB hand. RECUTTING REPAIRED SEARS By E. S. HALL Machinists, when called upon to space tooth over a repaired portion of a gear, sometimes at a loss to determine the pitch, not knowing the number of teeth contained in circle, or, through the old tooth being worn thin. A good plan is to measure round the circumference, ap- cimite 3V4 in., and count the number of teeth contained therein; this will be the diametrical pitch. Next find the number of teeth by multiplying the whole diameter of the gear by the
. Canadian machinery and metalworking (January-June 1919). iles a real lack of small appliancesOB hand. RECUTTING REPAIRED SEARS By E. S. HALL Machinists, when called upon to space tooth over a repaired portion of a gear, sometimes at a loss to determine the pitch, not knowing the number of teeth contained in circle, or, through the old tooth being worn thin. A good plan is to measure round the circumference, ap- cimite 3V4 in., and count the number of teeth contained therein; this will be the diametrical pitch. Next find the number of teeth by multiplying the whole diameter of the gear by the pitch ami subtract two. Example: In 3Vi in. we have 10 teeth and the whole diameter of -ear is in., then X 10 = 62 60, the number of teeth, and 10 the pitch. Now set the index head for 60 divisions and take a No. 2 10 pitch r (this to suit present example-*. re cutter on arbor and set centres to fterwards locking tble. Next mount the gear on centres and locate depth of e ( ) by touching the patch Vwith the cutter in motion. Raise table. /VlMfi^s^y after withdrawing work from under-neath cutter, and adjust space to not in motion, use the fine adjust-ment on index. Crank is necessary butdont move table on any account. Startmachine and proceed in usual mannerand the gear will be as good as new. LENGTHENING TWIST DRILLSBy C. E. Hall The accompanying sketch shows ablock for holding twist drills while hardsoldering extension shanks of any de-sired length, which has been used withgreat success for a number of years bythe writer. It frequently happens that an extralong drill is needed, but is not imme-diately obtainable. By utilizing any scrap material, suchas a piece of cast iron or cold rolled steeland shaping an opening across thecentre, varying fiom about % in. to 1 Vi in. long, threaded at both ends, the upperend of this piece being fitted with thefinger button Z. The weight W is apiece of cold rolled, 1 in. dia. and aboutVz in. long, turned, to the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmachinery, bookyear19
