Page 135 - Turner 1st sem Practicals

Job sequence

TASK 1
• Use a coolant while drilling and advance the drill slowly.
• Check the raw material for its size.
• Hold the job in a 4 jaw chuck and true it, keeping about • After completion of drilling throughout the job, reverse,
45 mm outside the chuck. and true the job, face to the required length as per
drawing, and turn Ø 40 mm.
• Set the facing tool to the correct centre height.
• Enlarge Ø 12 mm hole to Ø 20 mm hole by drilling at a
• Select and set the correct spindle speed, for facing. reduced spindle speed.
• Face one side first, and turn the Ø 40 mm for the • Set the boring tool in the tool post to the centre height
maximum possible length. and bore the drilled hole to Ø 25 mm
• Spot-face the job for drilling by centre drilling. • Check the bore size with a vernier caliper.
• Select the required size of drills including the pilot drill. Safety precautions
• Hold the drill in the tailstock spindle with the help of • Select proper spindle speeds as per size and
suitable sleeves after cleaning. operations.
• Select the spindle speed for drilling the pilot hold of 12 • Use pilot drill while drilling more than 20 mm drill size.
mm dia.
• Feed the drill slowly while drilling.
• Move the tailstock to a convenient position for drilling,
and lock the tailstock on the bed. • Use a coolant while drilling.

• Run the lathe and advance the drill so that it does the
drilling operation on the job held in the chuck.

TASK 2

• Hold the job in a 4 jaw chuck and true. • Perform R3 on a Ø 45 at one edge, with a 3R radius
tool.
• Face the end and centre drill.
• Deburr all the sharp edges and check with the precision
• Drill Ø 10 mm hole through and enlarge to Ø 14 mm. instruments.
by drilling.
Points to remember
• Bore through hole to Ø 15 mm.
• Hand feed should be uniform to obtain good surface
• Finish turn the outer dia. to size Ø 45 mm for possible finish; work with a round nose tool.
length.
• Set the radius tool properly to avoid chattering marks.
• Reverse the job, hold on Ø 45 mm and true.
• Limit the speed for internal recessing i.e., 1/3rd of the
• Face to maintain the total length of 40 mm. drilling r.p.m.
• Bore Ø 28 mm to length 33mm. Set the recessing tool. • Lock the carriage while recessing operation is done,
• Form recess 4 mm width as per drawing and R2 to avoid vibration.
Ø 35 mm. • Use a transfer caliper to measure Ø 35 mm.
• Check the radius with a radius gauge.

122 Producltion & Manufacturing : Turner - Exercise 1.3.39