New Britain

New Britain Image The following lesson outline details the tasks needed to be a machinist on a New Britain automatic bar machine. Some of these tasks require the trainee to explain how something works to insure they have the required understanding of the processes and are not simply memorizing procedures. All of the tasks listed will be a part of the Performance Test within each lesson. To learn more about these tests and the training process itself, see the Philosophy section.

This program accommodates the various stock size New Britain screw machines commonly found in use today. The MasterTask instructional technique employed will enable individuals to learn to set up and operate the machines quickly and easily. The first 9 lessons cover the basic setup and operating tasks. The final 6 lessons cover installation and setup of specific attachments. Both existing personnel and new trainees can utilize these training materials to develop or improve their performance.

Lesson 1: Basic Controls and Operations [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify by name, and explain the purpose for each of the major components of the machine including:
    1. Main Power Switch
    2. Front Control Station
    3. Rear Control Station
    4. Spindle Switch
    5. Stop Button
    6. End-of-cycle Light
    7. Out-of-stock Light
    8. Threading Switch
    9. Coolant Switch
    10. Cycle Off Switch
    11. Feed Start Button
    12. Feed Jog/Run Switch
    13. Feed Stop Button
    14. Spindles
    15. Spindle Carrier
    16. Carrier Lift Indicator
    17. Cross Slides
    18. Tool Slides
    19. Chip Conveyor
    20. Hand Crank
    21. Safety Control Rod
  2. Turn on the power to the machine.
  3. Start the main motor, spindles and feeding for normal operation.
  4. Stop the machine at the end of a cycle..
  5. Jog the spindles..
  6. Set the Threading Switch for either left-hand threads or right-hand threads.
  7. Inspect the Carrier Lift Indicator for proper indexing during operation.

Lesson 2: Stock Feed Components [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify by name, and explain the purpose for each of the major components of the stock feed system, including:
    1. Stock Reel
    2. Stock Feed Tubes
    3. Stock Feed Pawl
    4. Stock Feed Return Shoe
    5. Stock Feed Cams
    6. Pusher
    7. Stock Guide Bushing
    8. Feed Tube
    9. Feed Fingers
    10. Stock Release Lever
    11. Stock Stop
  2. Explain how the Stock Feed Cams, Stock Feed Slide, Stock Feed Pawl and the Stock Feed Return Shoe work together to provide feeding motion.
  3. Release the Pusher using the Stock Release Lever.

Lesson 3: The Collet Chucking System [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify by name, and explain the purpose for each of the major components of the collet chucking system, including:
    1. Collet
    2. Collet Chucking Tube
    3. Chucking Spool
    4. Chuck Fork Locking Latch
    5. Spacer
    6. Collet Adjusting Nut
  2. Explain the steps in the stock feeding cycle, including how the Collet, Pusher and Stock Feed Shoe work together to feed stock between cutoff and indexing.
  3. Explain the major steps in the machining cycle, including:
    1. Indexing
    2. Rapid tool approach
    3. Machining
    4. Cutoff at Position 6
    5. Tool Withdrawal
    6. Stock feed at Position 6

Lesson 4: Cleaning and Adjusting the Collets [ Top ]

After completing this lesson the operator will be able to:

  1. Properly stop the machine during operation and engage the Lockout mechanism to prevent accidental starting.
  2. Slide back the Stock Reel Tube then remove the stock, the Pusher, and all components of the Collet assembly.
  3. Clean the Collet and Collet Chucking Tube.
  4. Identify a Solid Collet and explain the range of bar sizes it is used for.
  5. Identify a Master Collet and Collet Pads, and explain the range of bar sizes they are used for.
  6. Inspect a set of Collet Pads, then assemble the Master Collet, Collet Pads and fiber inserts.
  7. Reassemble the Collet Tube and Spacer in the Spindle, then replace the Collet Adjusting Nut.
  8. With a bar end in the Collet, adjust the Collet tension using the Collet Adjusting Handle, then return the machine to operating condition.

Lesson 5: The Stock Feed System [ Top ]

After completing this lesson the operator will be able to:

  1. Properly clean bars and load them into the Stock Reel.
  2. Remove and replace the Pusher.
  3. Remove the Feed Finger and Stock Guide Bushing on a Pusher and replace both components.
  4. Explain the operation of the Stock Feed Cam, the stock feed slide and the cam roller, and describe what effect the cam size has on the amount of stock which is fed.
  5. Release the Trip Rod Actuating Collar, then change the Stock Feed Cam.
  6. Set the stock feed by loosening the Feed Adjusting Nut and adjusting the cam roller.
  7. Explain the operation of the out-of-stock mechanism, and adjust the mechanism for proper operation.
  8. Adjust the Stock Stop to provide the correct length of cutoff stock.

Lesson 6: Changing Feed and Spindle RPM's [ Top ]

After completing this lesson the operator will be able to:

  1. Identify the proper spindle speed gears and feed gears, given the layout sheet.
  2. Locate, identify and explain the purpose of the Spindle Speed gears and the Feed gears.
  3. Remove and replace the Spindle Speed gears, placing the drive gear on top and the driven gear on the bottom.
  4. Remove and replace the Feed gears, placing the driven gear on top and the drive gear on the bottom.
  5. Time a machining cycle and make sure it matches the cycle time on the layout sheet.
  6. Locate and explain the purpose of the Low Speed Dog.

Lesson 7: Cross Slide Cam Replacement [ Top ]

After completing this lesson the operator will be able to:

  1. Identify and explain the purpose of a Cross Slide Lead Cam, Guard Cam, Forming Gear and Positive Stop, and describe the action of the cams during the machining cycle.
  2. Select the proper cam for a Cross Slide using the layout sheet, then remove and replace the cam.
  3. Identify a circular form tool, a dovetail form tool and a flat form tool, and locate the cutting edge on each type of tool.
  4. Assemble and install a circular form tool, then adjust the tool for centering, longitudinal distance from the stock and depth of cut.
  5. Assemble and install a dovetail form tool, set the tool 2 3/4" from the top of the cross slide for centering, then adjust the longitudinal distance from the stock and depth of cut.
  6. Adjust the Positive Stop tension for tools when the cam has been replaced.

Lesson 8: Tool Slide Cam Replacement [ Top ]

After completing this lesson the operator will be able to explain:

  1. Locate, identify and explain the purpose of the Lead Cam, Guard Cam, Drawback Cam, Cam Drum and Positive Stop for a tool slide.
  2. Remove the tool slide cams from the machine with the cam roller at the high point.
  3. Back off the positive stop, select the proper cams according to the layout sheet, then install the cams on the cam drum.
  4. Correctly adjust the Positive Stop tension after replacing the tool slide cams.
  5. Describe the proper sequence to perform tool adjustments during setup.
  6. Install a spot drill and set the drill for the correct cutting depth according to the layout sheet.
  7. Install a drill which will use the full cam travel and set the cutting depth.
  8. Install and set the depth for drills which cut to a measured depth.

Lesson 9: Tooling [ Top ]

After completing this lesson the operator will be able to:

  1. Set the cutoff blade to just touch the stock with the Tool Slide cam at the proper point in the cycle.
  2. Center the cutoff blade to provide proper cutoff of the stock, with no tip or burr.
  3. Measure from the tool holder to the tip of the cutoff blade; remove the blade for sharpening, then reinstall at the proper dimension.
  4. Sharpen a cutoff blade at the proper relief and side rake angle for parts with or without a center hole.
  5. Identify commonly used drill types, including twist drills, chip-breaker drills, tapered length fast spiral drills, tapered shank drills, and spot drills.
  6. Describe the result of using drills with an incorrect cutting edge angle, unequal cutting edge lengths, or the wrong amount of lip clearance.
  7. Properly sharpen drills to the proper cutting edge angle, equal cutting edge lengths, and for the correct amount of lip clearance.
  8. Remove a drill for sharpening, then replace the drill in the machine at the proper depth using a tool gauge.
  9. Identify the sound of chatter and identify chatter marks on workpieces.
  10. Explain the most common causes of chatter, and the proper corrective action for each cause.

Lesson 10: The Recessing Attachment [ Top ]

After completing this lesson the operator will be able to:

  1. Identify the components and describe the operation of both the Universal recessing attachment and the Swing Type recessing attachment.
  2. Before installation, set the amount of side travel on a Universal recessing attachment.
  3. Clean the attachment base and tool slide, then install the recessing attachment in the machine.
  4. Install the Draw Rod Stop Block and Draw Rod.
  5. Install the recessing tool in the attachment, and properly center the tool using a tool gauge.
  6. With the feed cam on the high point, position the recessing tool to enter the part with the proper clearance; position the tool for the proper location inside the part for the recessing operation.
  7. Explain why the recess location must be fine adjusted before fine adjusting the depth of cut.
  8. Fine adjust the location of the recess using the nut on the end of the draw rod.
  9. Fine adjust the depth of cut using either the adjusting nut on the attachment or by repositioning the attachment on the tool slide.

Lesson 11: Shaving [ Top ]

After completing this lesson the operator will be able to:

  1. Explain the purpose of the shaving operation, and describe the amount of stock normally removed during shaving.
  2. Identify and explain the purpose of the components of the Shaving attachment.
  3. Before installing the shaving attachment, set the the distance between the bottom of the Roller and the top of the shaving tool to equal the stock diameter.
  4. Install the shaving attachment in the machine with the attachment bolts facing away from the Spindle.
  5. Adjust the shaving tool holder to align the shaving tool with the portion of the part to be shaved.
  6. With the shaving tool backed off, cut a part and gradually adjust the shaving tool in until the proper depth of cut is reached.
  7. Adjust a shaving tool to correct for a taper condition.

Lesson 12: Reaming [ Top ]

After completing this lesson the operator will be able to:

  1. Describe the purpose of the reaming operation, and identify the major components of the accelerated reaming attachment.
  2. Locate and describe the purpose of the Auxiliary Cam Drum, Auxiliary Cams and rollers, the Trip Switch, and the Auxiliary Brackets.
  3. Name the types of operations which can be controlled by the Auxiliary Cams.
  4. With the machine at the proper point in the cycle, install the Auxiliary Cams for the accelerated reaming attachment and check the roller operation.
  5. Install the sliding tool holder, attach the connecting rods and auxiliary bracket.
  6. Install the reaming tool in the holder, set the tool forward to touch the part.
  7. Attach the oil lines to the reaming attachment, then machine a part and check the dimensions.

Lesson 13: Tapping [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the components of the Universal Threading Attachment, including the threading spindle, tap, floating tap holder, push bar and push bar spring.
  2. Explain how the differences in the threading spindle speed allows the tap to cut the threads, then withdraw, for either left-hand or right-hand threads.
  3. Mount the auxiliary cam for the tapping operation and turn the Threading Switch to the proper setting.
  4. Mount the threading attachment in the machine and assemble the push rod to the auxiliary bracket.
  5. Install the tap holder and tap into the threading spindle.
  6. Set the initial tapping depth by positioning the tap, tightening the push rod jam nuts, and setting the speed-change cam near the trip switch roller.
  7. Fine adjust the tapping depth until the tapping depth is in tolerance.

Lesson 14: Die Head Threading [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the components of a die head threading attachment, including the die head, threading spindle, chasers, spring, yoke and threaded rod.
  2. Explain the die head threading cycle, and how the attachment cuts the threads then opens to withdraw without damaging the threads.
  3. Mount the proper auxiliary cam.
  4. Install the threading attachment to the tool slide.
  5. Slide the yoke and rod into the attachment.
  6. Install the die head and lock in place with the pin and cotter key, then assemble the trip nuts and push rod.
  7. Hand crank to start of the auxiliary cam feed then set the head and tighten the spring nuts.
  8. Adjust the attachment for the required thread length and fine adjust the nuts to achieve the proper closing of the die head.

Lesson 15: Thread Rolling [ Top ]

After completing this lesson the operator will be able to:

  1. Read and check all markings on the thread rolls and components to be sure all are correct type for the setup.
  2. Assemble the "C" roll, drive gear and thrust bearing into the number 1 arm, and the "D" roll and components onto the number 2 arm.
  3. Set the rolls to the proper spacing, making sure that the graduations on the attachment match
  4. Make sure that the rolls turn freely then tighten the attachment arms.
  5. Rough match the rolls by removing one roll and reinstalling with the match lines properly aligned.
  6. Fine match the rolls using the micrometer matching screw until the match lines are directly aligned.
  7. Install the thread roll cam and make sure the workpiece is not oversized.
  8. Mount the adapter and thread roll head to the cross slide.
  9. Use the adjusting screw to properly position the thread rolls to the workpiece.
  10. Remove the head and back off the feed adjusting screw, then use the micrometer positioning gauge to set the depth dimension.
  11. Remount the thread roll head and make final adjustments needed to produce threads within tolerance.