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Cincinnati 15-inch Tray-Top Lathe: First Cuts Guide

This section focuses on essential steps for safe operation and basic machining. Always prioritize safety and ensure each step is understood before proceeding.

Manual Reference

📄 Complete Cincinnati Tray-Top Lathe Manual (PDF)

This guide supplements the official manual with essential first-cuts procedures. Page references throughout correspond to the complete manual above.

1. Safely Power Up and Configure the Machine

Important Safety Precautions

Personal Safety

  • Read this manual thoroughly. Do not operate or service the machine until you have read and understood all instructions and safety precautions.

    Page 1

  • Wear appropriate PPE. Neckties, scarves, gloves, loose clothing, and jewelry must not be worn around moving machinery. Restrain long hair with a cap or net. Wear approved eye/face protection and safety-toe shoes with slip-proof soles.
  • Avoid distractions. Sudden movements, loud noises, and distractions are prohibited around machinery. Put down your smart phone!
  • Handle sharp tools with care. Use gloves or a shop cloth. Inspect tools before use.

Work Area Safety

  • Keep the work area clean. Dirty work areas with oil, debris, or water can cause falls.

  • Provide adequate clearance. A minimum of 18 inches clearance at the ends and rear of the lathe, and at least 36 inches at the front for the operator.

    Page 14, para. 3-4

  • Report unsafe conditions. Inform the Lead Technician or Safety Officer about worn, broken, or dull tooling.
  • Remove hand tooling. Wrenches, measuring equipment, and hammers must be removed from the machine immediately after use.

Pre-Operation Checklist

  • Cleanliness: Ensure the lathe and work area are clean and free of trip or fall hazards.

  • Machine Level: Verify the lathe's levelness. Recheck frequently during the first weeks of operation and periodically every six months.

    Page 18, para. 3-36

Lubrication Requirements

  • Thoroughly clean and oil the bed ways before moving the carriage or tailstock.

    Page 16, para. 3-10

  • Fill reservoirs to indicated levels on sight gages for headstock, quick change box, and apron.

    Page 13, para. 4-4

  • Daily checks:
    • Quick change gear box oil sight gage (1 pint required)
    • Apron oil sight gage, and pull out the one-shot oil plunger several times daily (1 pint required)
  • Oiling Ways and Leadscrew:
    • General purpose machine oil viscosity 200 to 220 seconds Saybolt at 100° F
    • Use your bench oil can to lubricate the leadscrew and ways using general purpose ways oil Page 24, Station 4 - 12

Power Up Procedure (All-Electric Drive - Standard)

  1. Main Disconnect: Ensure the main disconnect switch is in the OFF position prior to connection.
  2. Connect Power: An electrician must read electrical schematics before connecting to the power source. After connection, test all aspects of the electrical system. Ensure proper grounding and covered electrical systems.

  3. Turn ON: Turn the disconnect switch to the "ON" position.

    Page 20, para. 3-53

  4. Check Spindle Rotation: Momentarily engage the spindle start-stop lever in its upper position (jog the spindle). Facing the spindle from the tailstock end, it should rotate in a counterclockwise direction. If not, reverse the motor rotation before operating.

    Page 20, para. 3-53

Starting and Stopping

  • Forward Rotation: Pull the start-stop lever up.
  • Reverse Rotation: Push the start-stop lever down.

  • Quick Stop: The 15 inch Cincinnati Lathe is not equipped with friction brakes. To quick stop the spindle move the start-stop lever past the neutral position momentarily (tends to reverse the motor), then quickly return the lever to the neutral position to prevent reverse rotation.

    Page 20, para. 3-55

2. Chuck and Secure a Workpiece Correctly

Workpiece Support

  • The headstock spindle is provided with means for mounting centers, face plates, chucks, or other suitable devices to hold and drive the workpiece.

  • The tailstock is mainly used to support the right end of a workpiece when held between centers.

    Page 11, para. 1-9

  • For long slender shafts, use a steady rest or follow rest (see "Chatter" in

    Trouble Shooting Chart, Page 25)

Chucking Procedure

Chucking up your work is just like any other turning center. But here are some guiding reminders:

  • Select appropriate chuck/work-holding device.
  • Mount securely. Ensure the chosen device is correctly and tightly mounted to the spindle.
  • Center the workpiece. For turning between centers, align the headstock and tailstock centers.
  • Secure the workpiece firmly. The workpiece must be held securely to prevent movement during machining.
  • Retract the cutting tool a safe distance when loading and unloading workpieces.

3. Select Proper Spindle Speeds and Feeds for a First Cut

Spindle Speed Selection

  • Stop Spindle: ALWAYS stop the headstock spindle before attempting to make speed changes. Jog the spindle by hand if proper engagement of sliding gears is not obtainable. The Lathes transmission has non-sycromesh gearing.

    Page 21, para. 3-61a, Page 25, para. 5-1c

  • "Color-Match" Dial: Spindle speeds are changed using three levers, selected by reference to a direct reading "color-match" dial on the front face of the headstock.

    Page 21, para. 3-60

Speed Change Procedure

Example using Green Sector:

Page 21, para. 3-61:

  1. Move the outer adjustable selector ring (upper left-hand lever) so the green mark coincides with the green mark of the fixed reference ring.
  2. Move the intermediate adjustable selector ring (upper right-hand lever) so that the green mark coincides with the green mark on the outer ring.
  3. Move the inner dial (lower lever) so the desired speed in the green sector coincides with the green mark on the intermediate dial.

Spindle Speed Min / Max Range

  • Standard: 20-820 rpm

Thread and Feed Selection

  • Stop the headstock spindle. Jog the spindle if needed to engage spur gears
  • The quick change box provides multiple thread and feed changes using an index slide and positioning levers
  • Pull out the index slide plunger to disengage the tumbler gears, allowing the slide to drop
  • Position the levers as required for the desired feed rate
  • Move the index slide to align with the appropriate reference marking
  • Seat the index plunger in the location hole for final setting
  • A leadscrew reverse lever allows reversal of feeding direction for the carriage and cross slide

4. Engaging the Carriage, Cross-Slide, and Compound

  • The Carriage is supported on the bed ways and moves manually or by power
  • The Apron, suspended from the carriage, contains mechanisms for power feed to the carriage and cross slide
  • The Cross Slide, Compound Rest, and Tool Post are mounted on the carriage for tool positioning and movement control
  • Engaging Power Movements: Use the appropriate levers and selectors on the apron for carriage or cross feed selection

5. Make the First Clean Cut Safely and Verify Accuracy

Before Cutting

  • Ensure safety guards, shields, barriers, covers, and protective devices are installed
  • Safety disengagements or interlocks on handwheels must be in place
  • The spindle must be stopped when measuring workpieces, changing tools, or removing chips and grit.
  • Remove chips and grit with a chip rake or brush, never by hand!
  • Keep clear of moving parts. Keep all parts of your body off the machine table, table edge, out of the path of moving units, and out of the "machining area" during operations. Never lean or support yourself against any part of the machine.

During Cutting

  • Be attentive. During operation, be attentive to the machining process. Excessive vibration or unusual sounds indicate problems.
  • Watch for packed chips or grit that could damage tooling or machine parts
  • The spindle must be stopped before adjusting the coolant discharge nozzle

  • Never brake or slow down moving machinery with hands or makeshift devices

    Page 7

Power Management

  • Shut off unattended machines. Shut off power to your machine when leaving the operating area or at the end of the work period; never leave a machine running unattended.
  • Lock out power. Always lock the main disconnect device in the OFF position if the machine is left unattended.
  • Maintenance requires power off. Turn the master disconnect device to the OFF position before cleaning the machine or when guards/covers are removed.

Electrical Safety

  • High Voltage. Before working on any electrical circuits, turn the machine Main Disconnect Device "OFF" and lock it. Failure to follow this instruction may result in death or serious personal injury.
  • Ensure proper rotation. When the machine is installed, verify motors rotate in the proper indicated direction.

Verifying Accuracy

Manual Reference: Troubleshooting -

Page 25

Work not turned straight

  • Ensure headstock and tailstock centers are aligned
  • Use steady rest or follow rest on long slender shafts
  • Reduce overhang from the chuck
  • Re-level the bed using a precision level
  • Ensure the tool is on center when using the taper attachment

Work out of round

  • Adjust the tailstock center
  • Regrind or lap work centers if they are excessively worn or out of round