Type SP-4B Welding Gun
The Type SP-4B welding gun is shown on Figure 2.
balance and ease of handling have been accomplished by careful distri-
bution of weight and by directing the control cable, power cable, and
gas hose downward from the body of the gun. The weight of the gun in-
cluding a one-pound spool of welding wire is less than four pounds.
A spring return weld trigger (16) and recessed inch button (17) are
located in the handle of the gun. All electrical connections from the
gun to the control monitor, except for welding current connections are
made through the control cable (12) which plugs into a matching socket
on the control monitor.
the gun, is included with this booklet.
Welding current is brought to the gun by a 50 foot insulated copper
cable (25) that plugs into the control monitor by means of an insulated
plug. A 60 foot gas hose (1) is used to carry the shielding gas from the
gas regulator at the shielding gas supply. All cables and hoses to the
gun are tied together into one assembly.
The gun is equipped with a gear head wire drive motor (11) mounted in
the handle. Wire driving force is developed by squeezing the welding
wire between a knurled feed roll (2) mounted on the end of the gear head
motor shaft and an idler roll (19) mounted on the swing arm (15). Squeez-
ing force on the wire is obtained by turning the wire pressure screw (18)
which exerts pressure on the swing arm through a compression spring (20).
A four inch diameter spool of wire (13) is mounted on the wire spool
shaft (23). An adjustable spool brake (26) provides a controlled amount
of friction to prevent uncoiling of the wire. The wire spool is covered
by a transparent high impact plastic shield (9) attached to the spool
shaft by means of a captive thumb screw. This shield protects the wire
from spatter, yet, because of its transparency, allows the operator to
determine the amount of wire on the spool. The spool shaft is mounted on
an electrically insulated aluminum protective shield (28).
The guide tube (5) is an expendable copper tube which conducts welding
current to the welding wire as the wire slides through it. Position of
the guide tube relative to the end of the gas nozzle (8) can be changed
by releasing the insulated set screw knob (14). For 3/64 and .040 diameter
welding wires, the end of the guide tube should be about 1/8 to 1/4 of an
inch behind the front end of the nozzle. For smaller wires, the tip of the
guide tube should be even with or slightly ahead of the nozzle. Always use
the guide tube specified for the particular welding wire.
The gas nozzle (8) is specifically designed to completely exclude air from
the weld zone by proper direction of the shielding gas. For optimum gas
flow, the internal surface of the nozzle should be kept reasonably clear of
weld spatter by periodic cleaning. This nozzle may require occasional
replacement and is easily removable.