Machinist Shop Math: Speeds & Feeds, Tolerances, Bolt Circles & Tapers

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn six fractional drawing dimensions into decimal inches and millimetres, convert metric callouts to inches to four places and find the nearest 1/64 for decimal drill sizes.
• Turn illustrative surface speeds into spindle RPM for seven inch tools, compare the exact formula with the ×4 shop shortcut, cap the speed at the machine limit and do the same for four metric tools.
• Turn chip loads into table feeds for six tools, work out how long each cut takes, calculate the metal removal rate of a pocketing pass and back-calculate the chip load of an old program.
• Turn eight toleranced dimensions into upper and lower limits, grade measured parts PASS or FAIL with IF and AND, and classify a hole-and-shaft fit from its clearances.
• Calculate the angle, X and Y position of eight holes on a 4.5 in bolt circle for a mill program and check the pattern with a scatter chart.
• Calculate taper per inch, taper per foot and the included angle for five tapered parts and the tailstock offset for turning one of them between centres.
• Add the drill point length to five hole depths for the Z values of a program, calculate gauge block stacks for four sine bar angles and check which angle the stack actually built gives.
• Calculate cut times from feeds for five operations, total the cycle time of one bracket, turn it into machine hours and a price per part for a 250-piece job, and chart where the time goes.