Southbend SB1059F Half Nut Adjustment, Belts, To adjust the V-belts, To adjust the half nut

For Machines Mfg. Since 3/11 S E R V I C E EVS Toolroom Lathe w/DRO

Half Nut Adjustment

The clamping pressure of the half nut is fully adjustable with a gib that can be loosened or tightened by two set screws. Use this procedure to adjust the half nut if it becomes loose from wear, or it is too tight for your preferences. A half nut that is too loose will make it difficult to produce accurate work. A half nut that is too tight will increase the rate of wear on itself and the leadscrew.

V-Belts

V-belts stretch and wear with use, so check the tension on a monthly basis to ensure optimal power transmission. Replace all of the V-belts as a matched set if any of them show signs of glazing, fraying, or cracking.

Tools Needed:	Qty
Phillips Screwdriver #2	1
Open End Wrench 24mm	1

Tool Needed:	Qty
Hex Wrench 3mm	................................................. 1

To adjust the half nut:

1.Disengage the half nut, then remove the thread dial.

2.Turn the two set screws (see Figure 122) clockwise to tighten the half nut and counterclockwise to loosen it.

Make sure to turn the set screws in even amounts so that one end of the gib does not become tighter than the other.

Set

Screws

Figure 122. Half nut gib adjustment.

3.Engage/disengage the half nut several times and notice how it feels. The half nut is correctly adjusted when it has a slight drag while opening and closing. The movement should not be too stiff or too sloppy.

4.Repeat Steps 2–3, if necessary, until you are satisfied with the half nut pressure.

5.Re-install the thread dial.

To adjust the V-belts:

1.DISCONNECT LATHE FROM POWER!

2.Remove the motor access covers shown in Figure 123.

Headstock

End

Access

Covers

Figure 123. Locations of motor access covers.

3.Adjust the hex nuts on the motor mount bolts shown in Figure 124 to move the motor mount plate up or down and adjust the V-belt tension. When correctly tensioned, each belt should have about 3⁄4" deflection when pressed firmly (see Figure 124).

Motor Mount Bolts

Pulley

Deflection

Pulley

Figure 124. V-belt adjustment.

4.Tighten the hex nuts against both sides of the motor mount plate to prevent it from moving out of adjustment during operation, then re-install the access covers.

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