. Railway mechanical engineer . been lopted ™>th a left-hand spiral flute and of a standard length that will take care of the maximum and min-imum requirements. Heretofore, there were a great numberof different lengths which have been eliminated by standard-ization. By the adoption of the left hand spiral fluted reamer,the breakage has been reduced to about 20 per cent. Whileusing the straight fluted reamer trouble was encountered dueto the chipping out of portions of the flute and also chat-tering, while now this has all been eliminated, for the lefthand spiral retards the reamer to such a
. Railway mechanical engineer . been lopted ™>th a left-hand spiral flute and of a standard length that will take care of the maximum and min-imum requirements. Heretofore, there were a great numberof different lengths which have been eliminated by standard-ization. By the adoption of the left hand spiral fluted reamer,the breakage has been reduced to about 20 per cent. Whileusing the straight fluted reamer trouble was encountered dueto the chipping out of portions of the flute and also chat-tering, while now this has all been eliminated, for the lefthand spiral retards the reamer to such an extent that itdoes not gouge or seize, especially wliile reaming steel frameson locomotives. All our reamers are tapered 1/16 in. in 12in., and I feel confident that with the proper co-operationof the mechanical heads on the various railroads throughoutthe United States, this point could be agreed upon. DISCUSSION Several questions were raised regarding standard formsof reamers. There was some difference of opinion regard-. Fig. 7.—Reseating Tool for Blowoff Cock ing the relative advantages of flute in die form of spiralshaving short and long pitches. The majority favored longspirals on reamers used with air drills, but the statementwas made that the shorter spirals cut more rapidly, but re-quired heavier thrust to feed them. HEAT TREA TMENT OF STEEL BY ELECTRICFtJRNACES BY HENRY OTTOTool Foreman, A. T. & S. Topeka, Kan. There are in use at the Topeka tool room two high tem-perature electric furnaces and an oil tempering bath. Thefurnace used for extremely high temperatures has a carbonresister and carbon top plate. The service life of theseplates is about 125 hr., while the graphite bottom plateand electrode have a life of about .SOO working hours. Thisfurnace is expensive to maintain as the high heat usedcracks the walls inside of the carbon plate. This must berepaired, and it takes some time for the cement to dry so 616 RAILWAY MECHANICAL ENGINEER Vol. 93, No. 10 t
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