Tormach CNC Milling Machine PCNC1100

Check oiler level and top off as needed

Retract and release manual oiler plunger each time mill is powered on and after every four hours of operation

Clean chips from ways, carriage, and bellows’ covers

Spray exposed, non-painted metal surfaces with WD-40® or similar to prevent rust

Sign off on the daily mill maintenance

Remove coolant tank pump and clean out sediment buildup in tank

Inspect electrical cabinet vent(s) for dust build up

Wipe vents with clean cloth if necessary

Use compressed air to remove dust if accumulation is excessive

Pull back way covers and inspect ways and ball screw for proper lubrication (on all axes)

Sign off on the monthly mill maintenance

Grease and adjust drawbar if needed

Clean chip basket on coolant tank

Check air gauge/regulator for proper PSI (90 PSI minimum)

Use mild cleaner to clean all exterior surfaces (no solvents)

Inspect spindle belt for nicks, fraying, or other noticeable signs of wear

Inspect way covers as needed to ensure proper operation; replace as needed

Inspect oil system for blockages; clean/replace as needed

Check lubrication hoses for signs of wear or cracking; replace as needed

Check X-axis flex conduit for signs of wear or cracking; replace as needed

Sign off on the mill maintenance

Each axis utilizes a double-nut, pre-loaded ball screw. The pre-load in the ball nut is set at the factory by placing a precision ground spacer between the two ball nuts. Lost motion attributable to the ball screw assembly is less than 0.0004”. Ball nut preload is not operator-adjustable.

The ball screw mount bearings are located near the driven (motor) end of each ball screw. These are a pre-loaded angular contact bearing pair and are operator-adjustable. Under typical use, these bearings should be adjusted so that observable lost motion is between 0.0005” to 0.0013”.

Figure 9.4 and Figure 9.5 show a cross section of a typical ball screw shaft mount. The ball screw shaft is in the center and the crosshatched section in Figure 9.5 is the axis motor mount that houses the bearings. There are two angular contact ball bearings, forming a pre-loaded pair. The ball screw Cover Plate holds the two outer races together, along with the Spacer that is between them.

The inner races are held between the Sleeve (left side) and the shoulder cut into the ball screw shaft (right side). The Sleeve is held against the left inner bearing race by the Adjustment Nut and a Lock Nut. When the Adjustment Nut is screwed tighter toward the bearing pair, the preload increases.

Over time, it may become necessary to adjust the ball screw bearing preload to account for bearing wear. The bearing preload will also need to be adjusted if a bearing replacement becomes necessary.

Improper ball screw bearing preload will result in either excessive backlash in the mill if it is too loose, or rapid wear and excessive friction if it is too tight. It should be noted that if your ball screw, ball nut, or angular contact bearings are worn, or if your gibs are adjusted too tight, you will not achieve appropriate lost motion values.

Figure 9.6 shows how the force of preload is transmitted through the bearings, from the inner race to the outer race. In a preload pair, this force is then transmitted back to the inner race by an opposed bearing. It should be apparent that the correct orientation of the angular contact bearing is critical to the operation.

To adjust the angular contact bearing pair preload, the following kit is required (see Figure 9.7):