Tornos Bechler / Strohm

Tornos Bechler Image The following lesson outline details the tasks needed to be a machinist on a Tornos-Bechler Swiss screw 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.

These fifteen lessons will teach the trainee to operate and setup a Tornos or Bechler single-spindle cam-operated Swiss screw machine. The trainee will also learn to setup the Combined Three-Spindle Attachment to perform drilling or threading operations.

Lesson 1: Basic Operations and Controls [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of components in the tooling area of the machine.
  2. Explain how machine components operate during machining cycle, including bar feeding, bar rotation, collet and tool cutting operations, bar support from guide bushing, cutoff of finished piece.
  3. Locate, identify and explain purpose of normal operating controls on machine control panel. This includes controls on Tornos, and controls on newer and older Bechler machines.
  4. Use operating controls correctly, including starting and stopping motor, engaging and disengaging clutch, and jogging machine.
  5. Locate and identify the Coolant Flow Valve, and adjust the valve to control the flow of coolant into the tooling area.

Lesson 2: Lubrication and Bar Feed [ Top ]

After completing this lesson the operator will be able to:

  1. Locate all oilers on the machine, including adjustable, non-adjustable and pressure type.
  2. Lubricate all oilers on the machine at the appropriate intervals, using the correct grade and type of lubricant.
  3. Describe the normal flow rate of an adjustable type oiler, and adjust flow rate.
  4. Select the proper heavy grade oil for the camshaft gear box reservoir, the coolant pump reservoir, and the main gear box reservoir.
  5. Locate all oil reservoirs on the machine, check the oil levels using the eye gauges or sight gauges, and fill the reservoirs to maintain the correct levels.
  6. Locate and remove the coolant scrap filters and scrap screen, disassemble the scrap filters, clean and reassemble all components and replace them in the coolant reservoir.
  7. Add coolant as needed to the coolant reservoir to maintain the proper level.
  8. Locate, identify and explain the purpose of all major components of the bar feed system, and explain how these components work to feed the bar into the machine.
  9. (Tornos With Automatic Stop) Remove the bar remnant, clean and oil a new bar, load the bar into the machine and restart the machine to resume part production.
  10. (Tornos Without Automatic Stop) Finish the last part, remove the bar remnant, clean and oil a new bar, load the bar into the machine and restart part production.

Lesson 3: Basic Tool Adjustments [ Top ]

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

  1. Locate and identify the two Rocker Arm tool holders on the machine, and explain the types of cutting operations which are commonly performed with each tool.
  2. Locate and identify the three Vertical tool holders on the machine, and explain the types of cutting, forming, and other operations which are commonly performed with these tools.
  3. Name three basic types of tools used on Tornos and Bechler machines, and explain the operations which are done with each.
  4. Read a part print and determine the required dimensions and acceptable tolerance range for each workpiece feature.
  5. Locate radial and lateral adjustment micrometers for each of five tool holders and explain amount of adjustment which will be made for each micrometer space.
  6. Explain the correct amount of micrometer adjustment on a metric micrometer to change a workpiece dimension by inches.
  7. Make radial and lateral adjustments to the Rocker Arm tools to change the diameter and length of workpiece features.
  8. Make radial and lateral adjustments to the Vertical tools to change workpiece diameters and lengths, using the micrometer devices to perform accurate adjustments.
  9. Adjust two diameters which are cut by Tool 1 by adjusting the larger diameter using tool holder micrometer, then adjusting smaller diameter using Rocker Arm Stop Peg.
  10. Change overall length of the workpieces by adjusting the Headstock Stop Peg.

Lesson 4: The Collet Assembly [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the components of the collet assembly.
  2. Locate, identify and explain the purpose of the collet opening and closing system.
  3. Describe how the collet cams, collet chucking lever, chucking bobbin, collet toggles, and intermediate sleeve work together to open and close the collet.
  4. Remove the bar from the machine, then loosen and remove the spindle nose cap and remove the collet. (On Bechler machines, also loosen and remove the spindle nose cap lock ring.)
  5. Remove the collet sleeve from the spindle using a collet extracting device, a brass rod and a hammer.
  6. Remove the collet sleeve and intermediate sleeve from the spindle using a brass bar and mallet.
  7. Clean and lightly oil the components of the collet assembly and the intermediate sleeve. Also clean inside of the spindle.
  8. Replace intermediate sleeve and collet assembly into spindle, then replace and tighten spindle nose cap when all components are aligned and fully seated. (On Bechler machines, also replace and tighten the spindle nose cap lock ring.)
  9. Locate and explain the purpose of the Collet Tension Collar.
  10. Adjust the collet tension collar so that a bar will slide through without binding when the collet is open and will be gripped firmly when the collet is closed.

Lesson 5: The Guide Bushing [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the Guide Bushing, components of the bushing assembly and the bushing holder in the machine.
  2. Explain how an adjustable bushing for round bar stock works to support the bar during machining.
  3. Describe the two main types of adjustable bushings.
  4. Remove the bushing assembly from the bushing holder, then disassemble and clean the components of the assembly.
  5. Reassemble the bushing assembly and replace in the bushing holder.
  6. Adjust the bushing tension so that a bar of stock rotates freely without excessive play in the bushing.
  7. Use a drill press and bar stock to lap a bushing until there is free movement of the stock through the bushing.

Lesson 6: Basic Tool Making [ Top ]

After completing this lesson the operator will be able to:

  1. Select the proper size tool blank for making a cutting tool to the proper dimensions.
  2. Identify and explain the purpose of common tool faces, rakes, and reliefs or clearances, and describe the types of tools and cutting operations each is used for.
  3. Read a job layout and determine the required dimensions and angles for the cutting tools.
  4. Rough grind the soft metal around the carbide tip of a tool blank to clean up and increase the size of the tool's work area.
  5. Clamp the tool blank in the grinder tool holder in the correct direction and on the correct side of the grinding wheel for each feature being ground.
  6. Loosen the lock levers, set the upper and lower angle adjustment gauges for the proper angles being ground, then tighten the lock levers.
  7. Rough grind the tool face angles until the dark carbide surface has been removed, then fine grind the face angles to provide a smooth finish on the tool tip.
  8. Clamp the tool, set the required angles on the angle gauges, rough and fine grind the required cutting and clearance angles on one side of the tool.
  9. Rough grind the opposite side of the tool, then fine grind the opposite side in small amounts, measuring the tool width after each grinding pass until the correct width is achieved.
  10. Clamp the tool, set the required angles on the angle gauges, rough and fine grind the required cutting and clearance angles on one side of the tool.
  11. Clamp the tool, set the required angles on the angle gauges, rough and fine grind the required nose angle and nose clearance angle on the tool.
  12. Hand grind the heel of the tool to provide adequate clearance when the tool is installed in the machine.
  13. Visually inspect the entire tool tip for the proper surface finish; check all critical dimensions and angles with micrometers or an optical comparator.

Lesson 7: Tool Sharpening and Centering [ Top ]

After completing this lesson the operator will be able to:

  1. Explain and identify common types of wear and damage on the edges of cutting tools.
  2. Disconnect and remove a vertical tool slide from the machine, inspect the tool using a magnifying eyepiece, and replace and reconnect the tool slide in its tool holder.
  3. Stop machine and remove a tool while tool is in working position.
  4. Grind away some of the soft metal from around the tip of a tool to be sharpened.
  5. Clamp a tool into the grinder tool holder, set the proper angles, rough grind tool if necessary, fine grind to correct sharpness.
  6. Inspect a sharpened tool for proper sharpness, measure critical dimensions and angles.
  7. Replace a sharpened tool into its tool holder, positioning it against the partially cut feature from when the tool was removed.
  8. Adjust the sharpened tool radially and laterally until the workpieces are in tolerance.
  9. Explain the results of tools which are below center and tools which are above center.
  10. Check the centering of a tool by manually facing off a slight amount of stock from a bar, then inspecting the end of the bar for a sharp center point.
  11. Adjust the centering of a tool by loosening the centering lock screw, adjusting the centering screw (Tornos) or the centering counter screws (Bechler), then tightening the lock screw.
  12. Center tool #1 by aligning the tool tip with the sharp center point which was cut on the face of the bar by another tool.

Lesson 8: Setting Up Pulleys and Gears [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the components of the drive mechanism, including belts, pulleys, and the Bechler indirect drive pulley shaft.
  2. Determine the proper spindle speed and production speed from the job layout.
  3. From the Pulley Chart, determine the correct motor pulley and drive shaft pulley to use to achieve the required spindle speed, then select the correct pulleys from the storage area.
  4. Remove the old spindle speed pulleys and install new pulleys then replace the drive belt and adjust the belt tension to no more than one inch of play.
  5. Remove and replace the spindle speed pulleys, and adjust the tension of the drive belts, on a Bechler machine with an indirect drive shaft.
  6. Locate, identify and explain the purpose of the stepped pulleys, belt, drive gear and driven gears which control the machine production speed.
  7. From the production speed chart, determine the correct belt position for the stepped pulleys and the correct size gears, then select the gears with the required number of teeth.
  8. Change the position of the drive belt(s) on the stepped pulleys to the proper steps for the required production speed.
  9. Remove the drive gear and driven gears from the machine, and install the proper gears for a setup. (On Bechler, this includes removing the drive belt and lower stepped pulley to access the gears.)
  10. Check the machine production speed by counting the number of times that the collet opens - by watching the collet chucking lever - in one minute.
  11. Adjust the stepped pulley belt position or replace gears if necessary to achieve proper production speed.

Lesson 9: Setting Up Cams [ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the Headstock Cam, the Rocker Arm Cam, and the Vertical Tool Cams.
  2. Identify and explain the operation of cam rises, falls, dwells and degree lines.
  3. Remove the headstock cams, rocker arm cams, vertical tool cams, washers and lock nuts from the camshaft.
  4. Handcrank the collet opening cam or collet closing cam, as called for on the layout, to the zero degree position.
  5. Install the headstock cam and an auxiliary cam if required for the setup, positioning the cams with their zero degree lines against the followers.
  6. Install the rocker arm cam and auxiliary cam if required, install spacers and the cam locknut, position the cams with their zero degree lines against the followers and tighten the locknut.
  7. For vertical tool cams with zero degree lines: install the vertical tool cams and locknuts, position each cam with the zero degree line on the follower and tighten the locknuts.
  8. For vertical tool cams with degree lines with the tool number: install the vertical tool cams, align the cam with the tool number degree line marked on the headstock cam. Tighten the cam locknuts.
  9. Handcrank the camshaft through a full cycle, watch all installed cams to be sure that they are aligned with the zero point on the headstock cam then re-engage the headstock to its cam follower.

Lesson 10: Additional Setup Adjustments [ Top ]

After completing this lesson the operator will be able to:

  1. Adjust the headstock plate, the headstock stop peg, the stop bar and the headstock return spring to provide the proper headstock travel during the entire machining cycle.
  2. Adjust the headstock transmission ratio gauge for the setup being performed.
  3. Adjust the vertical tool transmission ratio gauges for a setup.
  4. With the headstock all the way back, adjust the amount of play on the headstock stop peg using a feeler gauge to check the clearance.
  5. On the Bechler machine, adjust the amount of clearance (play) between the headstock cam and its follower, and the auxiliary headstock cam and its follower.
  6. Adjust the amount of play on the rocker arm cam by adjusting the rocker arm stop peg.
  7. With stock in the machine, check and adjust the timing of the collet opening so that opening occurs when the headstock cam follower is between the high point and the fast fall.
  8. Check and adjust the timing of the collet closing so that closing occurs within the acceptable portion of the machining cycle for collet closing.
  9. Adjust the automatic stop mechanism so that the machine will stop in the feed up position when the bar stock runs out.

Lesson 11: Producing the First Part at Setup [ Top ]

After completing this lesson the operator will be able to:

  1. Install and properly position the cutting tools for a setup, then with bar stock in the machine, center each cutting tool.
  2. Determine the correct distance from the tool line for each tool by reading the job layout.
  3. Face off a bar using the parting-off tool, then use the clean bar face to key each tool the proper distance from the tool line.
  4. Rough adjust the cutting depths of the tools to produce all basic diameters on a workpiece; adjust back turning tools, the parting-off tool, then front turning tools.
  5. Measure a rough-cut workpiece, then adjust the tool lateral micrometers to achieve the correct workpiece lengths.
  6. Adjust the headstock stop peg to achieve the correct overall length of a workpiece.
  7. Adjust the rocker arm stop peg to adjust a smaller diameter produced by tool one, when tool one produces more than one diameter on a part.
  8. Adjust the follower on the auxiliary rocker arm cam to adjust a part diameter produced by tool two which is controlled by the auxiliary cam.
  9. Adjust I.D. features produced by centering, boring, and recessing tools to produce diameters and depths within tolerance.
  10. Setup and adjust a knurling, chamfering or finishing tool to produce the proper secondary feature within tolerance.

Lesson 12: Drills and Drill Sharpening [ Top ]

After completing this lesson the operator will be able to:

  1. Identify common types of screw machine drills, explain the types of features for which each drill is best suited, and identify the features and angles of each type of drill.
  2. Explain the angle degree of drills used for normal drilling, and the angle degree used for spot drilling.
  3. Inspect drills for worn or broken edges.
  4. Set the angle adjustment gauges on a drill sharpening fixture to the proper lip clearance angle and primary clearance angle.
  5. Mount a twist drill into the drill sharpening fixture, sharpen the primary and secondary clearance angles on both sides of the drill.
  6. Use drill gauges to check lip angles and lip lengths on a sharpened drill.
  7. Thin the web of a twist drill on a twist drill sharpener, thinning both sides of the web the same amount.
  8. Sharpen a "D" drill or a flat drill using diamond tool sharpening wheels, with a special drill sharpening fixture to hold the drill.

Lesson 13 (Tornos): Combined Three Spindle Drilling and Threading
Attachment: Drilling
[ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the components of the Tornos Three Spindle Drilling and Threading Attachment.
  2. Describe the types of drilling operations that the three spindle drilling and threading attachment is used for.
  3. Install and time the spindle cam segments for a setup requiring up to three drills on the combined three spindle attachment.
  4. Install and time two indexing cams on the attachment, then handcrank the machine to be sure that the indexing is properly timed to the spindle cam segments.
  5. Create the proper clearance for operation, when necessary, by repositioning the combined attachment, the indexing cam drum, the spring tension arm, and the spindle cam drum.
  6. Install the drill collets and drills on the attachment spindles.
  7. With drill one at the start of its work position, vertically center all of the drills using the vertical centering rod.
  8. With each drill at the start of its work position, horizontally center each drill using the proper adjusting device, checking each adjustment by manually pushing the drill into the spinning bar stock.
  9. Increase the play of the spring pressure stop peg on the indexing cam of spindle three.
  10. Make a rough depth adjustment for each drill, machine a part, measure the hole depth(s), then fine adjust each drill until all depths are in tolerance.

Lesson 13 (Bechler): Combined Three Spindle Drilling and Threading
Attachment: Drilling
[ Top ]

After completing this lesson the operator will be able to:

  1. Locate, identify and explain the purpose of the components of the Bechler Three Spindle Drilling and Threading Attachment.
  2. Explain the drilling cycle on the attachment and how the spindle cam rises and falls control the cycle.
  3. Install spindle cam drum follower, then install and time the spindle cam segments for a setup requiring up to three drills on the attachment.
  4. Install and time two indexing cams on attachment, handcrank the machine to be sure that the indexing is properly timed.
  5. Create the proper clearance for operation, when necessary, by repositioning the attachment.
  6. Install the drill collets and drills on the attachment spindles.
  7. With each drill at the start of its work position, center each drill using the proper adjusting device and make a rough depth adjustment.
  8. Machine a drilled part, measure the hole depths, then fine adjust each drill using the fine depth adjustment screw.

Lesson 14 (Tornos): Combined Three Spindle Drilling and Threading
Attachment: Tapping and Threading
[ Top ]

After completing this lesson the operator will be able to:

  1. Identify and explain purpose of internal and external threading tools on combined three spindle attachment.
  2. Explain threading process and how speed of threading spindle and speed of rotating bar work together to thread part and retract tool.
  3. Install and time spindle cams and indexing cams for threading operation, including all required drill spindle cam segments and threading spindle cam segment.
  4. Select and install threading pulleys and belts, tighten belts to the proper tension, run the machine to check the belt travel.
  5. Install and time the clutch tripping cam segment, then handcrank the machine to check the timing of the change in threading spindle speed.
  6. Install any required drills, center them to the bar stock, and adjust the drill depth, then install and center a tap.
  7. Adjust the start and stop of the tap using the depth adjusting screw, then fine adjust the tapping depth using the turnbuckle, until the tapped depth is correct.
  8. Assemble, adjust, install, and center a chaser type die head for an external threading job.
  9. Adjust the start and stop of the die head until the threaded length is correct.
  10. Machine workpieces, measure or gauge the thread diameter and fine adjust the thread depth until it is within tolerance.

Lesson 14 (Bechler): Combined Three Spindle Drilling and Threading
Attachment: Tapping and Threading
[ Top ]

After completing this lesson the operator will be able to:

  1. Identify and explain the purpose of internal and external threading tools used on the combined three spindle attachment.
  2. Explain the threading process on the attachment, and how the speed of the threading spindle and the speed of the rotating bar work together to thread the part then retract the threading tool.
  3. Install and time the spindle cams and indexing cams for a threading operation, including all required drill spindle cam segments as well as the threading spindle cam segment.
  4. Select the proper threading pulleys according to the pulley chart.
  5. Install the threading pulleys and belts, with the large and small pulleys in the correct order on the pulley shaft, and tighten the belts to the proper tension.
  6. Install the pin which prevents rotation of the threading tool during withdrawal from the workpiece, if required for a job.
  7. Install the clutch engaging cam segment, and time it to about 90 degrees ahead of the threading cam fast rise, then handcrank the machine to check the timing of the change in threading spindle speed.
  8. Install any required drills, center them to the bar stock, and adjust the drill depth, then install and center a tap.
  9. Adjust the start and stop of the tap, then fine adjust the tapping depth using the depth adjusting screw, until the tapped depth is correct.
  10. Assemble, adjust, install, and center a chaser type die head for an external threading job.
  11. Adjust the start and stop of the die head, then fine adjust the threading depth using the depth adjusting screw, until the threaded length is correct.
  12. Machine workpieces, measure or gauge the thread diameter and fine adjust the thread depth until it is within tolerance.
  13. Adjust the automatic stop mechanism on the Bechler attachment so it will shut down the machine if a tap breaks.

Lesson 15: Working with No Bushing or with a Revolving Bushing [ Top ]

After completing this lesson the operator will be able to:

  1. Explain the types of workpieces which are more easily produced without using a guide bushing, and which types must use a revolving bushing.
  2. Remove bushing assembly, install a collet guard over the spindle nose, then setup the headstock for working without bushing.
  3. Remove the normal bushing from the machine and install the proper shape and size collet for use with the revolving bushing.
  4. Assemble the revolving bushing and the bushing body, install in the machine with the key and keyway aligned, then replace the bushing lock ring. (Also install bushing adjusting sleeve and spindle nose nut on the Bechler machine, adjust bushing tension before installing the assembly in the machine.)
  5. Assemble the two-pin extension and the spindle nose cap, install in the machine, tighten the spindle nose cap to the spindle and the two-pin extension to bushing body.
  6. On the Tornos machine, install the bushing tension adjustment nut and, with bar stock, adjust the tension of the bushing.
  7. Check the operation of the revolving bushing.