Miller Bobcat 250 - User Manual

OWNER’S MANUAL
OM-249336M
2019-05
Processes
Stick (SMAW) Welding
MIG (GMAW) Welding
Flux Cored (FCAW) Welding
TIG (GTAW) Welding
Description
Engine Driven Welder/Generator
For product information,
Owner’s Manual translations,
and more, visit
www.MillerWelds.com
Bobcat
™
250

Summary

SECTION 1 - SAFETY PRECAUTIONS - READ BEFORE USING

1-1. Symbol Usage

Explains safety symbols used throughout the manual.

1-2. Arc Welding Hazards

Details potential dangers associated with arc welding processes.

1-3. Engine Hazards

1-4. Compressed Air Hazards

1-5. Additional Symbols For Installation, Operation, And Maintenance

1-6. California Proposition 65 Warnings

1-7. Principal Safety Standards

1-8. EMF Information

SECTION 3 - DEFINITIONS

3-1. Additional Safety Symbol Definitions

Defines safety symbols specific to CE products.

3-2. Miscellaneous Symbol Definitions

Defines general symbols used throughout the manual.

SECTION 4 - SPECIFICATIONS

4-1. Serial Number And Rating Label Location

Indicates where to find serial and rating plate information.

4-2. Weld, Power, And Carbureted Engine Specifications (Kohler CH730)

Technical specifications for CH730 engine models.

4-3. Weld, Power, and EFI Engine Specifications (Kohler ECH730)

Technical specifications for ECH730 engine models.

4-4. Environmental Specifications

Details operating and storage temperature ranges.

4-5. Dimensions, Weights, And Operating Angles

4-6. Duty Cycle And Overheating

4-7. Fuel Consumption

4-8. Generator Power Curve

4-9. Volt-Ampere Curves

SECTION 5 - INSTALLATION

5-1. Installing Welder;Generator

Instructions for mounting and securing the welder/generator unit.

5-2. Grounding Generator to Truck or Trailer Frame

5-3. Installing Exhaust Pipe

5-4. Engine Prestart Checks

5-5. Connecting Or Replacing The Battery

5-6. Electronic Fuel Injection (EFI) System And Battery Information

5-7. Weld Output Terminals

5-8. Connecting Weld Output Cables

5-9. Selecting Cable Sizes*

SECTION 6 - OPERATION

6-1. Front Panel Controls (See Section 6-2)

Overview of the welder's front panel controls.

6-2. Description of Controls (See Section 6-1)

6-3. Cold Weather Engine Operation

6-4. Typical Stick Welding Connections And Control Settings

6-5. Typical MIG Welding Connections and Settings

6-6. Typical MIG Connections And Settings Using Weld Control And Spoolgun

6-7. Fuel;Hour Gauge Descriptions

SECTION 7 - OPERATING AUXILIARY EQUIPMENT

7-1. Generator Power Receptacles

Details the available generator power receptacles and their ratings.

7-2. GFCI Receptacle Information, Resetting, And Testing

7-3. Simultaneous Weld And Power

7-4. Wiring Optional 120;240 Volt Plug

SECTION 8 - MAINTENANCE AND TROUBLESHOOTING

8-1. Routine Maintenance

Schedule and tasks for routine maintenance.

8-2. Maintenance Label

8-3. Servicing Air Cleaner

8-4. Electronic Fuel Injection (EFI) System And Servicing Information

8-5. Overload Protection

8-6. Changing Engine Oil, Oil Filter, And Fuel Filter

8-7. Adjusting Engine Speed (Kohler CH730 Carbureted Units)

8-8. Adjusting Engine Speed (Kohler ECH730 EFI Units)

8-9. Troubleshooting

SECTION 9 - PARTS LIST

9-1. Recommended Spare Parts

List of recommended spare parts with part numbers and descriptions.

SECTION 10 - ELECTRICAL DIAGRAMS

Figure 10-1. Circuit Diagram For Welder;Generator

The main electrical circuit diagram for the unit.

SECTION 11 - GENERATOR POWER GUIDELINES

11-1. Selecting Equipment

Guidance on selecting auxiliary equipment for use with the generator.

11-2. Grounding Generator to Truck or Trailer Frame

Procedures for safely grounding the generator to a vehicle frame.

11-3. Grounding When Supplying Building Systems

11-4. How Much Power Does Equipment Require?

11-5. Approximate Power Requirements For Industrial Motors

11-6. Approximate Power Requirements For Farm;Home Equipment

11-7. Approximate Power Requirements For Contractor Equipment

11-8. Power Required To Start Motor

11-9. How Much Power Can Generator Supply?

11-10. Typical Connections To Standby Power

11-11. Selecting Extension Cord (Use Shortest Cord Possible)

SECTION 12 - STICK WELDING (SMAW) GUIDELINES

12-1. Stick Welding Procedure

Step-by-step guide for performing stick welding.

12-2. Electrode And Amperage Selection Chart

12-3. Striking An Arc

12-4. Positioning Electrode Holder

12-5. Poor Weld Bead Characteristics

12-6. Good Weld Bead Characteristics

12-7. Conditions That Affect Weld Bead Shape

12-8. Electrode Movement During Welding

12-9. Welding Lap Joints

12-10. Welding Groove (Butt) Joints

12-11. Welding T-Joints

12-12. Weld Test

12-13. Troubleshooting

SECTION 13 - GMAW WELDING (MIG) GUIDELINES WHEN USING A VOLTAGE-SENSING FEEDER

13-1. Typical GMAW (MIG) Process Connections Using A Voltage-Sensing Wire Feeder

Connections for MIG welding with a voltage-sensing wire feeder.

13-2. Holding And Positioning Welding Gun

13-3. Conditions That Affect Weld Bead Shape

13-4. Gun Movement During Welding

13-5. Poor Weld Bead Characteristics

13-6. Good Weld Bead Characteristics

13-7. Troubleshooting - Excessive Spatter

13-8. Troubleshooting - Porosity

13-9. Troubleshooting - Excessive Penetration

13-10. Troubleshooting - Lack Of Penetration

13-11. Troubleshooting - Incomplete Fusion

13-12. Troubleshooting - Burn-Through

13-13. Troubleshooting - Waviness Of Bead

13-14. Troubleshooting - Distortion

13-15. Common MIG Shielding Gases

13-16. Troubleshooting Guide For Semiautomatic Welding Equipment

TRUE BLUE WARRANTY

LIMITED WARRANTY

Details the terms and conditions of the limited warranty.

Owners Record

For Service

Miller Bobcat 250 Specifications

General

Rated Output	250 A at 25 VDC, 100% Duty Cycle
Generator Power	11, 000 Watts Peak, 9, 500 Watts Continuous
Engine	Kohler CH730
Fuel Type	Gasoline
CC/CV	CC/CV
Phase	Single-phase
Frequency	60 Hz
Type	Engine Driven Welder
Welding Processes	Stick (SMAW), MIG (GMAW), Flux-Cored (FCAW), TIG (GTAW)
Fuel Tank Capacity	12 gallons
Welding Amperage Range	40 - 250 A
Open Circuit Voltage	80 VDC
Voltage	120/240 V
Outlet Types	120V 20A Duplex, 240V 50A