Southbend SB1059F User Manual

Page of 140
-84-
For Machines Mfg. Since 3/11
EVS Toolroom Lathe w/DRO
S E R V I C E
Leadscrew Shear Pin 
Replacement
10.54mm
8.75mm
5.8mm
0.5mm
0.2mm
0.2mm
3.74mm
NOTE: Shear Pin Material = S45C (SAE 1045)
Figure 130. Shear pin specifications.
Tools Needed: 
Qty
External Retaining Ring Pliers #1 ....................... 1
Magnet ................................................................... 1
Safety Goggles ....................................................... 1
Blow Gun w/Compressed Air ................................ 1
Light Machine Oil .................................. As needed
The leadscrew is secured to a connecting collar 
that is part of the headstock drivetrain with 
the use of a soft-metal shear pin. The shear pin 
is designed to break and disengage the power 
transfer to the leadscrew to help protect more 
expensive lathe components in the case of a 
carriage crash or the lathe is overloaded.
Contact South Bend to order a replacement shear 
pin (Part Number PSB1042PF0927) or use the 
specifications in Figure 130 to fabricate your 
own.
4.
  Put on safety glasses.
Figure 132. Shroud washer and shear pin alignment.
Cutout
Shear Pin 
Head
Shroud
Washer
3.
  Rotate the shroud washer on the leadscrew 
(see Figure 132) so that the cutout lines up 
with the shear pin head.
If you fabricate your own shear pin, make sure 
to use the material and dimensions specified 
in
 Figure 130. Otherwise, the shear pin may 
not provide the intended protection and lathe 
damage could result.
To replace the shear pin:
1.
  DISCONNECT LATHE FROM POWER!
2.
  Clean debris and grime from the shear pin 
area (see Figure 131).
Figure 131. Location of shear pin.
Location of
Shear Pin