GATE 2021 ME (ME1) – Question 51
The XY table of a NC machine tool is to move from P(1,1) to Q(51,1); all coordinates are in mm. The pitch of the NC drive leadscrew is 1 mm. If the backlash between the leadscrew and the nut is 1.8°, then the total backlash of the table on moving from P to Q is _____ mm (round off to two decimal places).
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Correct answer: 0.00 to 0.02
Explanation
One revolution advances 1 mm, so the lost displacement associated with 1.8° clearance is $1(1.8/360)=0.005$ mm.
Backlash is a reversal clearance, not an error accumulated every revolution over the 50 mm travel. Rounding 0.005 to two decimals gives **0.01 mm**.