c* bottom clearance coefficient

em space width at middle-line m-m  of the rack-cutter  (mm)

g-g tip-line of rectilinear profile of the rack-cutter

ha addendum of basic rack tooth (mm)

ha⁎ addendum coefficient of basic rack tooth

hη total depth of boundary fillet — type IIa of the rack-cutter (mm) hξ total depth of boundary fillet — type IIb of the rack-cutter (mm) m module (mm)

m-m middle-line of the rack-cutter

n-n rack-cutter centrode

r reference circle radius (mm)

ra tip circle radius (mm)

rb base circle radius (mm)

rf root circle radius (mm)

rq undercutting circle radius (mm)

sb tooth thickness at base circle (mm)

sg tooth thickness at tip-line g-g of the rack-cutter  (mm)

sm tooth thickness at middle-line m-m of the rack-cutter (mm)

X addendum modification of the rack-cutter (mm)

x addendum modification coefficient

Xmin minimum addendum modification for non-undercutting (mm)

xmin minimum addendum modification coefficient for  non-undercutting

Xη, Yη coordinates of boundary fillet — type IIa of the rack-cutter (mm) Xξ, Yξ coordinates of boundary fillet — type IIb of the rack-cutter (mm) z number of teeth

α profile angle for the rack-cutter (deg)

αa pressure angle at tip circle (deg)

αq pressure angle at undercutting circle (deg)

δr radial undercutting (mm)

δ⁎r

radial undercutting coefficient

δt tangential undercutting (mm)

δ⁎t

tangential undercutting coefficient

λr relative radial undercutting (%)

λt relative tangential undercutting (%)

ρ fillet radius of the rack-cutter (mm)

ρ* fillet radius coefficient of the rack-cutter

ρmax⁎ maximum fillet radius coefficient of the rack-cutter

ρa curvature radius of involute curve at tip circle (point a) (mm)

ρq curvature radius of involute curve in boundary point q (mm)

ρη curvature radius of boundary fillet — type IIa of the rack-cutter (mm)

ρη,A curvature radius of boundary fillet — type IIa in point А

ρξ curvature radius of boundary fillet — type IIb of the rack-cutter (mm)

φ