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BACKLASH AND LEAD ACCURACY

What is backlash and why does it matter? What about lead accuracy? How does it affect me and my machine? Or in other words... "In search of 'perfection'"

Also: Ballscrew and ACME Leadscrew Accuracy Charts

1. PREFACE
2. INTRODUCTION
3. BACKLASH IN A MANUAL WORLD
4. CNC TO THE RESCUE?
5. EXPECTATION
6. A PERFECT CIRCLE
7. OTHER DESIGN CONSIDERATIONS AND THE PROS AND CONS
8. CONCLUSION
9. RESOURCES

BACKLASH IN A MANUAL WORLD

Not quite. You've just experienced backlash! This is the axial play/lash/slop between the threads of the nut and the threads of the screw. Many machines have this and perhaps this is more noticeable on machines without any sort of mechanism to adjust for backlash. More on that later.

While backlash can be frustrating especially when you do not have some form of table positioning system in place such as a digital readout (DRO) that employs the use of axial measuring devices (like the digital calipers you use to measure your workpieces), it does not critically affect the outcome of your workpiece as long as you, the operator (aka "human CNC machine"), keep track of your table positioning.

Imagine life without a DRO - you would have to know what your machine's backlash is (and this backlash increases with time unless you keep your machine adjusted properly) and "do the math" during respective axial changes. (Ever wonder why those dials on your handwheel move around? This is one reason!).

With DRO, you are literally the motor cranking the handwheels to move the table and workpiece per your dimensions. Much easier!