Chapter 15


*15.2* Find the expansion of a 3 m cylindrical bar of steel. The bar diameter is 40 mm. *a.)* Over a temperature range of 0 C to 100 C. *b.)* Over a temperature range of 30 C to 31 Celsius degrees. *c.)* Over a temperature range of 68 F to 70 degrees Fahrenheit.

*15.3.1* Backlash compensation is often misunderstood. Every system has backlash as a normal condition. Answer the following: *a.)* How is a CNC system compensated for its backlash? *b.)* What triggers backlash compensation? *c.)* What are the units of backlash? *d.)* How is the backlash compensation turned off?


	*15.3.2* The amount of existing mechanical backlash is found before any adjustments, mechanical or control-side. Answer the following: *a.)* Why is backlash checked with feed, rather than handle moves? *b.)* Make a procedure for checking the linear backlash on a turning center. Include: i.) A sketch showing axis movement and indicator placement. ii.) A short incremental test program with spindle off). iii.) A blank chart for recording three trials of test data. *c.)* Repeat Part b.) This time for checking the rotary backlash on a machining centers rotary 4th axis.

	*15.10* Starting with 12 Vdc, how much does the voltage drop: *a.)* Across a closed set of switch contacts? *b.)* Across 10 feet of 16 gauge copper wire


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