CNC Project X Axis Z Axis Wiring Control electronics

Y Axis.

The Y axis bearing bars, also of precision ground steel bar are mounted onto the cast aluminium X axis mounts via machined holes, at this point allowances must considered for the cable conduit or trunking to be fitted and to give the cables somewhere to run so as to prevent wires from breaking and getting tangled when the machine is in use.

The "Y" axis bearings can next be made, here i decided to make one large casting, saw in half,and machine to size by boring out the center and cut the slit to hold in place the bearings and wiper seals, it is not apparent in these photos but there are two linear ball races in each casting, this is to stop any form of twist or rotational forces caused by the motor assembly or by action when the machine is running, the wiper seals are to stop dirt ingress and are vital to maintain good operation, the saw slits will be sealed at a later date with silicone rubber to prevent any further ingress of foreign matter.

Machining process is to clamp the large face to the machine table and gently face of the motor mounting face, next clamp the just machined face to the table and repeat the process on the large face, careful clamping or support methods are needed to reduce ringing vibration and the inevitable bad finnish, only small cuts can be made, when the two faces are ready then the body of the casting can be squared up in a machine vice that has been previously trued with a dial gauge.

Having finished the squaring the next job is to cut the motor hole and bearing support hole, this is done on a rotary table with the two holes machined in the same set-up to preset alignment.

The motor is squared up onto the casting and the four motor securing holes are drilled to take M5 set screws.

The casting is directly mounted onto the X Axis bearing blocks with three M6 Screws to the bearing blocks and a third to the spacing plate shimming the third will tilt the Casting and set the face of the casting at 90° to the "Y" axis bars as shown below in the series of photographs.

Up to this point although the motors have been fitted i have deliberately not connected the ball screw shafts to the motors so that an idea of alignment can be gained by the free running of the screws and shafts, the X Axis shaft will rotate quite freely and is an easy task to move the carriage along the bed to the opposite end and to rotate the ball screw at relatively high speeds, this is in part accomplished by the fact that the bearings at each end only have a very light coating of oil, and are very free to rotate, the Y Axis of the other hand i have used pre greased and sealed bearings, the resistance to travel by pushing the carriage is now remarkably high, but the torque to rotate the ball screw by hand is only a little more than the X Axis.

I have again used two ball races at each end to help address mal alignment

At this point by pushing and pulling the carriage in the Y Axis direction any slip or movement of the ball screw can be measured, i measure with a digital vernier and machine out a suitable spacer from silver steel ( drill rod ) as after all i have plenty to use!!!!!!!, this i lap on a stone to fit and the result should be A big ZERO end slop or drift

the non driven bearing support for the "Y" Axis was machined out of solid aluminium, ( a large riser ).

Machining of ballscrew ends.

Two methods can be used here, one is to bore out the soft Center and insert a steel pin which is either threaded into the screw or glued with suitable anaerobic adhesive, or machine down to the required diameter, I used the latter and quite successfully machined the hard outer surface with a large old braised on tungsten carbide tipped tool. this worked well but left a bad finnish, this was resolved by honing with a diamond hone whilst still in the lathe, this method it is possible to bring the diameter to within 0.001 inch and be paralell with a fine smooth finish, almost like it was ground.