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Lathe trainer’s manual

A step-by-step guide to lathe inductions

Can trainees fail this course?

This course is designed to be a basic introduction to lathe use that can be completed by a sensible, careful member of the space.

Trainees can be considered “trained” if they show a good understanding of the following points: - All safety and PPE measures - Proper lubrication of the machine, including turning the oilers off and on - Proper observation of the “Checks before use” and “Checks after use” posters

Use your judgment. If you do not feel that the trainee you are inducting can work independently, ask that they come for a second session at a later date.

1. Clothing and PPE

  1. What PPE is necessary to use the lathe?
  2. Eye protection

  3. Closed-toe shoes

  4. What other safety precautions should be taken regarding personal safety and clothing?

  5. No long hair/ loose clothing
  6. No gloves
  7. Jewellery off

If the trainee is struggling, indicate that all this information is printed above the lathe itself!

  1. Discuss any further questions the trainee has about clothing and PPE.

2. General safety

  1. Why are the following rules are in place?

  2. NO lone working

  3. NEVER leave chuck key in chuck
  4. Never operate the lathe under the influence of alcohol, drugs, or fatigue

  5. If using a file, the file must have a proper handle fitted

  6. Discuss any further questions the trainee has about the “FOR YOUR SAFETY” poster above the lathe. Explain why these measures are in place – some are obvious, others less so to a beginner.

  7. Ask the user if they have any questions so far.

3. About the lathe

  1. Ask the trainee to point out the headstock, tailstock, carriage and bed and ask them what each of the above parts does.

  2. Ask them to name 3 other parts and what they do.

(These questions are to give you a sense of how well informed the trainee is about lathes in general)

  1. Remind the trainee that the lathe is a precision machine and should be treated CAREFULLY. Do not place objects on the slideways, do not force the parts, etc.

  2. Briefly show them how the chuck rotates, how the carriage and tailstock and handwheels work.

  3. Invite the trainee to turn the handles to get a feel for the machine. This is especially important for complete novices who have never touched a lathe.

4. Workholding

  1. Show the trainee how the 3-jaw chuck works with the key.

  2. Mention the concept of overhang/stickout (max 3x work diameter) and how tail support works, but you don't need to show this necessarily.

  3. Show them how to change a chuck

  4. Place protective wood on bed of lathe
  5. Open belt guard
  6. Use special 3D-printed spanner to lock gear
  7. Insert chuck key in chuck
  8. Pull chuck key towards you and unscrew chuck
  9. Inspect spindle threads for swarf, debris

  10. Replace with 3-jaw again and put some plastic or aluminium stock in the chuck (you'll need it for the next steps)

  11. Explain to the trainee how to change the chuck jaws around and that they must be put back in a certain order. 3, 2, 1 to remove, 1, 2, 3 to put back. You don't need to demonstarte this as it can be time-consuming.

  12. Briefly explain how other workholding methods work, but there is no need to demonstrate:

  13. Faceplate
  14. Turning between centres
  15. Collet chucks

Make sure the trainee understands that they will have to research the best work holding method for their chosen project.

  1. Remind them that the manuals live with the lathes and can/should be consulted.

  2. Reinforce the following with the trainee:

  3. Use the protective wood and DO NOT drop chucks. Treat them very carefully.
  4. DO NOT run the lathe backwards when using the screw-on chucks or faceplate as they could unscrew during use. Explain the physics of this so the trainee understands why it happens.
  5. Hold the work securely within the jaws, don't hold the very tip of the workpiece so that the jaws "pinch" inside the chuck

5. Tooling

  1. Show the trainee the HSS and carbide tools and explain how to change/rotate a carbide insert.

  2. Explain the main shapes we have, specifically the main cutting tool, the parting tool, and a chamfering tool.

  3. Show them how the tool post works and how to adjust tools to centre height.

  4. Put a carbide cutting tool in the toolpost – you'll need it for the next step.

  5. Mention that grinding HSS tools is something they will have to research themselves, if they have a need for it.

6. Checks before use

It's nearly time to actually use the lathe!

  1. Run through the “Checks before use” poster together, covering any discussion points as they arise.

  2. Ensure the lathe is set at top speed (for carbide) and explain how speeds are changed.

7. Basic operations

Now demonstrate the following four procedures. Encourage the trainee to ask questions along the way.

A good method is to explain what you're going to do, then do it, then ask the trainee to do the same, advising them as necessary as they go.

Facing

  • Set the toolpost angle so you can make the cut
  • Rotate the chuck by hand and touch off on a high spot of the workpiece
  • Pull the tool back clear of the workpiece
  • Apply a cut with the top slide (20 thou or 0.5mm to start with)
  • LOCK THE CARRIAGE!
  • Make the cut with the cross slide
  • Ask the trainee to have a go themselves

Turning

  • Following the same principle, touch off on the surface of the workpiece
  • Pull the tool out clear of the workpiece and apply a 20-thou/0.5mm cut (or so)
  • Make a cut, stopping well shy of the jaws
  • Ask the trainee to have a go at making some similar cuts
  • Show the trainee what is meant by backlash at this point. Feel free to play with facing and turning cuts to get a feel for the machine.
  • Talk about depth of cut here. Mention some sensible upper limits (40 thou in aluminium and brass, 20 thou in steel?).

Drilling

  • Show the trainee how to remove and replace accessories in the tailstock with the heavy bar that dislodges them.
  • Ask them to install the drill chuck and a centre drill. Help them if necessary.
  • Move the tailstock up towards the workpiece. Lock the tailstock.
  • Explain the principle of drilling the hole, but ask the trainee to do this themselves if they feel comfortable.
  • Otherwise, centre drill the end and then enlarge with a larger drill size to demonstrate the principles. Repeat if necessary.

Parting

  • Slow the lathe speed right down (you can explain this more fully to the trainee later)
  • Fit a parting tool into the holder
  • Square up the tool holder relative to the work
  • Set up the cut so it's as close to the chuck as possible – explain the balance between rigidity and safety here.
  • Explain the need for cutting fluid (not so much on plastic)
  • Demonstrate the cut, maintaining constant gentle pressure
  • Ask the trainee to have a go. They may stall the lathe, so be on hand to switch off the motor and explain what went wrong. But let them try again to get the process right.
  • Remind the trainee that they should never part between centres or with tail support

8. Final checks

Run through the “Checks after use” poster, covering any discussion points as they arise.

9. Bonus material

If there is time, you can explain these more advanced concepts.

Speeds

  • Show the trainees how to use the belt to select speeds. Explain that speeds and feeds is a complex topic, and they can look up the relevant speeds for their chosen project.

  • Show them how the backgear works to select slow speeds

  • Using ground-down allen key, loosen cap screw on back gear
  • Slide toothed key upwards to disengage
  • Move backgear lever to upper position, so both sets of cogs mesh nicely
  • Backgear is now selected, providing three slower speeds
  • Reverse this process to put lathe in "normal" ungeared drive mode
  • Close guard
  • Remind them NEVER to adjust these settings, including the backgear, when the lathe is running.

If using carbide in the Myford, use the fastest speed at all times, unless parting, when the slowest (ungeared) speed should be used.

Feeds

  • Explain that the carriage has a power feed
  • Ensure lathe is not running
  • Open up the change wheel cover
  • Show the trainee the cogs inside and the diagrams on the inside of the cover
  • Tell them that they are used to set carriage feed rate and/or thread pitch
  • Invite trainees to research the topic for themselves as it can be quite complex