Wordsandphotographs:RICHARDROSENTHAL
Notamotorcycle component this month, but something manyofuswill
use during drilling operations, althoughwemaybeunawareof its presence,
significance or that it isastandardised fit across manymachine and powertools.
Morsetapers
anytool-holders, drills and
other cuttingtoolsfittothe
drivingspindlepowersource,
stationaryspindle oflathetailstocksorother
equipmentbymeans of anappropriate
taperedshank (male) whichfits precisely
intoataperedfemalesocket.
Fine,but howcould webeunaware?
Manyolder (andsome new)bench,hand
and pillar drillshavechuckssecured
byscrewfittoarbours whichappear
permanentlyfittedto the tool(andin some
casestheyare)but bydesignit is often
securedbythefitofits taperedmalesection
intoamatchingtaperedfemalesocket.
This methodoffittingtaperedshanksto
matinginternallytapered sockets is known
as ‘machine tapers.’ Makers of engineering
equipmentcould maketheir tapersfittoany
sizeand angle offit, althoughsteepangle
tapers don’twork well in this situation.Most
employastandardtaperfitknownas the
‘Morsetaper.’
Morsetapersarenumbered, ascheme
whichrelatespreciselytothetaper
size(tablesavailable),and as far as us
motorcyclistsareconcerned,Morsetapers
one, two, threeand four areappropriate.
Oneisthe smallest and theyincreaseinsize
incrementally.WemayencounterMorse
tapersfiveand six ifworkingwith heavy
equipment, such aslargemills.Thusmany
chucks,tapereddrills,some mill tools and
the likefittotheequipments’femalesocket,
driven orstationaryasappropriate,by
Morsetaperfit.
Happily for us motorcyclists,we’re
usually concernedwithjust one taperfitat
anyone time,but production engineering
equipment–evenold equipment–such
as drillingmachinesmayrun twoormore
drillsat anyone time.Thesecould beof
vastlydifferentsizes andsuitablefitsockets
will beof differentsizes too.
AsMorsetaper oneisthe smallest, logic
applies in that small tapereddrills,chucks
and other smaller toolsfittotheirmating
femalesocketusingMorsetaper one. And
again, logically,largertools will rely on
correspondinglylargertaperfits,progressing
up theMorsetaper size range.Thesame
guidelinesapplytothoseannoyingtool/
equipmentmakerswhohave chosen taper
fits whichdon’t correspond totheMorse
tapersystem.
Again, this isfine,but what if weneedto
fitasmall drill or tinychuckwith aMorse
taperonemale shank intoafemaleMorse
taperthreesocket,forexample?
Newandsecond-handMorsetaper
adaptorsockets arereadilyavailable to
bridge thegap.Thesehaveanouter (male)
tapercorrespondingtothe next Morsesize
larger oreventwoorthreesizes largerand
theinnerfemale tapertosuit size (perhaps
twoorthreesizes) smallerthanits outer.
Ta kingasimple example,tofitadrill with
Morsetaper one shank toatailstocksocket
with Morsetaper three,one could use
Morsetaper number one andtwosockets
bytelescopingthemtogetheror usea
single Morsetaper onetothreesocket.This
approachworksacrosstheMorsetaper range.
With regardstoremoval. Asweknow,
tapers holdfirmandMorsetapers
formachine toolingisnoexception.
Thoughtfully,makers of loosesockets
machineslotsintothetaperwall at the
pointofthe tool shank end andsupply
slide-throughwedgestodrivethe tool
shank freeof the femalesocket.
Classiccomponents Classics
ife
98 THE CLASSICMOTORCYCLE|SEPTEMBER 2019
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