CNC Project Y Axis Z Axis Wiring Control electronics
The X Axis
X Axis motor and bearing mount.
The main stepper motor is fixed to the back left hand support
leg by means of a stout aluminium bracket which also provides a clamp to hold
the X axis bar to the support leg. this was done by simply cutting a "V"
into a 50mm 20mm slab of aluminium (a billet cast into a steel channel and machined
flat and square) with two socket M6 X 75mm bolts. The top is set level and square to the table before temporarily
tightening down, two 10mm thick blanks were first machined to be of identical
size then machined as a pair to take both the Stepper motor and lead screw bearing
block, these are then fitted to teach side of the top clamp and then Fixed into
position The bearing block is turned to fit with two ball races, this
is now fitted to the motor and checked that the holes are true. Adjustments had to be made to account for the fact that the
assembly plates were not parallel at this point and a third fixing hole drilled
into the support leg to prevent the assembly twisting out of alignment.
ballscrew end's are turned down to 12mm diameter to fit the ball bearings used at each end and end drift is brought to zero by turning a steel shim out of silver steel (drill rod) and hardening it, this is then fitted in front of the first ball bearing at the non driven end and ballscrew, adjustment is made by honing on a diamond whetstone.
When all is done the lead screw should spin freely with a flick of your fingers.
At this point work must switch to the Y Axis in the form of fitting the cross slide and Z Axis mounting plate to ensure that the Y Axis bars are fixed parallel before the X Axis bearing blocks can be given a fixed distance, it is important to machine the two end plates separately as the resulting differences in dimensions between the X Axis bearing blocks would result in the Y Axis binding and not run freely.
When this is done work can now switch back to the X Axis and fit the ballnut, final alignment of the lead screw can now take place, I used a steel milling parallel and a dial gauge to check for runout, by fixing the magnetic dial holder to one of the steel Y Axis bars and slide the parallel along the lead screw, noting the runout.
Any adjustment required in the lead screw should be completed before the ball nut is fitted, if all is correct the X Axis carriage should rotate the ballscrew by pushing it along,any stiffness should be investigated.