User Guide - 135ST

Date: 16-12-2022

The complete operators guide for Weldclass FORCE 135ST Stick / TIG Welder

FORCE 135ST Stick-TIG Welder 

1. Set Up

Warranty Registration:
To qualify for extended warranty, please register here within 30 days of purchase.

Work Lead:
Ensure that all connections are firmly fitted to the cable.
The work lead should be connected to the positive (+) terminal for most Stick applications*.

Earth Clamp & Lead:
Ensure that the clamp is very firmly fitted to the earth cable.
The earth lead should be connected to the negative (-) terminal for most Stick applications*.

*Refer to electrode manufacturers specifications / recommendations for correct / best polarity. Many electrodes will operate on either polarity - read more.


2. Controls & Settings

Front panel

Welding Modes

Press the Amp control knob to switch between Stick and TIG. The Machine will remember your last settings when switching modes.


Adjusting Hot Start and Arc Force

Press and hold the Amp Control knob to enter Hot Start and Arc-Force settings.

Hot Start 

Hot start provides extra power when the striking the arc, to counteract the initial high resistance between the electrode and workpiece. It makes igniting the electrode easier and prevents it from sticking when cold.

Adjustable from 0 – 10. 0 is Hot-Start off, 10 is maximum Arc Force (around 20-30A higher than the set welding current/amps, up to a maximum 'ceiling' of 140A).

Arc Force

Also known as ‘Dig’ or ‘Arc Control’. A Stick welder is designed to produce constant output current (CC). This means that the welding voltage varies to maintain constant current (amps), depending on the arc length, electrode type, etc. This can cause instability in some welding conditions as electrodes will have a minimum voltage they can operate with and still have a stable arc. Arc Force control boosts the welding power if its senses the welding voltage is getting too low. The
higher the arc force adjustment, the higher the minimum voltage that the power source will allow. This effect will also cause the welding current to increase.

Adjustable from 0 – 10. 0 is Arc Force off, 10 is maximum Arc Force (around 20-30A higher than the set welding current/amps). This is useful for electrode types that have a higher operating voltage requirement or joint types that require a short arc length such as out of position welds.



See section 5 below.


3. Power Supply

The 135ST is designed to operate on a 10A 240VAC power supply.

If an extension cord must be used, it should be minimum cable core size 2.0mm2 for length of up to 10m, or minimum 2.5mm2 for length up to 20m. Using extension leads of over 20m is not recommended.

This machine has a wide input power variation tolerance (~170-265V), allowing it to operate off generator power. Recommended generator size is minimum 7ka, or ideal 8+kva. A suitable quality generator should have a THD (total harmonic distortion) rating of less than 6%. Most reputable generator suppliers will be able to specify the THD ratings on their product. For more details on generator use, see: Using Generators to power Inverter Welders - your questions answered  


4. TIG

In TIG mode, the 135ST is suitable for "Lift-Arc" DC TIG welding (10-130A) of mild-steel, stainless-steel, copper and chrome-molly up to a thickness of approximately 3mm. 

A TIG welding torch and gas regulator is required to set up the 135ST for TIG welding.

Note that the 135ST is NOT suitable for TIG welding of aluminium, as this requires machines with AC/DC TIG function - such as the Weldclass 201T AC/DC TIG welder.

TIG Welding Guide 


5. VRD

VRD (Voltage Reduction Device) function is disabled by default*.  To have VRD activated on your machine, please contact your Weldclass distributor, or click here to email Weldclass Technical Support team.

When enabled, VRD function reduces the open-circuit voltage (OCV / U0) from 77V to a safer level of 13.5V.  The machine senses when the operator is striking an arc (resistance between electrode and work piece is less than 200 Ohmns) and switches VRD off to provide full voltage / welding power.  When welding stops, VRD will activate again.  Whenever VRD is activated, the VRD LED light on the control panel will be illuminated. 

VRD is mandatory for some work sites (especially mine sites). Whilst VRD reduces the risk of electrical hazard, striking the arc can be more challenging, especially with specialist or hard-to-run electrodes. 

*Machines with first 6 digits of serial number 202212 & above have VRD disabled by default, with option to enable on request.  Machines with first 6 digits of serial number prior to 202212 have VRD permanently activated / on.