Tools/metallathe/induction

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Harrison M300 Metal Lathe Inductions and Workshops

Some of the tools at the Hackspace are potentially hazardous to use, for these tools members are required to have an induction before they can use them. Inductions provide the most basic information on how to safely and effectively use the simpler functions of the tools, we appreciate that some members may have professional experience on some of these tools and in this case please tell your induction provider and the induction may be very reduced and just cover any risks or procedures specific to rLab. Some tools have multiple levels of induction in order to cover more advanced uses of that tool without making the basic induction take too long, higher induction levels will introduce some of the more advanced features of the tools but as with all inductions are only intended to provide basic information on the capabilities of the tools and how to use them safely. Some members of rLab may be willing to offer more detailed tuition beyond basic induction level or offer guided practice sessions in exchange for beer money or assistance on their own projects.

For all tools you are only required to take level-1 induction before use, after that you may perform any task that you feel confident you can do safely, higher levels of induction may be useful to you in performing more advanced operations but are not required before doing tasks covered in them so long as you're confident of your ability to handle those tasks without risk to yourself, others, or the tool.

PLEASE NOTE : All induction providers are volunteers who are providing inductions to the best of their ability but are NOT qualified instructors. Inductions are provided on a best-effort basis but you and you alone are responsible for your safety while using the tools and for satisfying yourself that you can operate the tools safely. There are professional training courses available from various providers in Reading and the surrounding area if you feel they are appropriate for the level of work you intend to undertake. Reading these notes is NOT a substitute for an in-person induction.

Note for wiki editors : Please do not edit induction pages unless you are one of of the people that gives that induction

Level-1 induction

This is the most basic induction and provides only the absolute essentials.

Topic Detailed contents Rationale
Proper Clothing
  • 'Workshop appropriate' clothing - you're going to get dirty and probably splashed with coolant etc
  • No open-toed shoes or sandals.
  • Sleeves tied back, no loose or flowing clothing, long hair tied back, risks of rings.
  • Mention the catch points of the chuck and the 2 powerfeed screws.
  • Mention the main slide handle can catch things, mention loose clothing can catch the handwheels and upset work.
Obvious Safety issues, don't want to get pulled in!
PPE
  • Goggles when using lathe, gloves possibly for loading/unloading sharp objects but NEVER while actually using the Lathe.
  • Proper positioning of the guard and warning that it's mostly to catch splatter and offers only limited protection
Basic safety information
Nomenclature The proper names for all the various parts of the Lathe Got to have common language to communicate effectively
Start-up/Shutdown
  • Location of main power switches, location of the 2 E-Stops, using the control lever most of the time but it's OK to use the brake peddle as a normal stop if the part geometry makes it necessary, location of card reader once we have it.
  • Clean the lathe off before use if it's noticeably dusty, especially the slideways.
  • Turn the Lathe off whenever you leave it, even briefly.
  • Putting the "Out of Order" sign on the lathe if you see a problem and notifying maintenance team
Stopping and starting! Turning off when unattended in case someone brushes power lever
Oil System Location of the 3 sight glasses, what they should show, who to contact if they don't, using automatic one-shot oiler Don't want people running the machine when dry
Materials Selection Which materials can the Lathe operate on, types of metals and their properties, plastics that can be turned and modifications needed to do so, materials that cannot be used on the lathe.
YES NO
  • Regular Steels
  • Aluminium (with caution)
  • Brass
  • Acrylic
  • Nylon (caution about long swarf)
  • Delarin
  • Wood (but see level 2)
  • Polycarbonate (but see level 2)
  • Ceramics & Glass
  • GRP & Carbon Fibre
  • Hardened & chromed Steels (but see level 3)
People need to be able to choose the right material for their project, other materials to be covered in Level 2+ Inductions
Mounting the tools
  • The advantages of HSS (cheap, robust, resharpenable) and why not to use carbide till level-2
  • Brief visible inspection of tools before fitting, checking for sharpness
  • Holding the tools in the holders, keeping as little as possible sticking out
  • How the holders grip properly and how to fit them into the quick-change toolpost and tightening the toolpost.
  • Mention how to set the toolpost to perpendicular
  • Don't cover angled tool positions unless it becomes necessary

Cover only the basic steel roughing tool, leave the rest for level 2 inductions

Tailstock mounting Fitting the drill or the live centre, aligning the tang, keeping the tapers clean and dry, ejecting the tool Need to know this to set tool height
Setting tool height
  • Locking/Unlocking the tool height adjustment - Adjustments can only be made when unlocked, comparisons only made when locked, setting it using the live-centre in the tailstock
  • How accurate this needs to be and effects of getting it wrong.
    • Too low - Tool grabs and work rides up
    • Too-high - excessive friction and tool failing to cut.
  • Don't adjust unless obviously quite far out as they're normally left correct

We'll get a lot of broken tools if this isn't done right

Mounting Workpeices
  • Inwards gripping only using the 3-jaw chuck (Outwards and Jaw-change for level-2)
  • Smallest amount possible exposed, maximum of 3-5 diameters, large/Long/Delicate pieces can't be held at this level of induction
  • Use of the through-bore
  • Approximate truing and even tightening
  • The 3-jaw is not accurately concentric, so don't take workpiece out till you're finished
  • Not leaving the key in the chuck! This is the most common source of accidents on lathes and can cause serious injury

Holding the work securely but only on a basic level for induction.

The 3 slides
  • Mainslide for fast parallel moves but warn it's easy to slam the tool into something, can be used for turning when absolute parallel motion is vital but usually much easier to use top-slide.
  • Cross slide for perpendicular moves, show how the dial works and how to zero it and mention that's it's calibrated for DIAMETER and not radius
  • Top slide for small controlled reasonably parallel moves up to 100mm long, describe how it can be used to cut tapers and how to re-set it to parallel. Don't cover details of taper-turning, that's level 2 induction.

How to move the tool around!

The Lamp
  • Positioning the mag-base lamp properly, taking care that it won't foul over the full range of motion intended. Beware of stroboscopic effects.

Getting a clear view, and not being fooled by strobe effect

Selecting suitable speeds Using the chart above the Lathe. It's OK to start out going slower than the chart suggests to give yourself more time to react as you learn and work up to the full speeds listed Just the chart, calculations and modifications for various operations are for level 2 inductions
Make sure feeds are off
  • Making sure that the powerfeed and screwcutting feed are disengaged before starting up the Lathe.
  • The two levers that control then and what the disengaged position is.
  • Warn how fast things can go wrong if they're left engaged!

Don't cover using the powerfeeds for induction level 1 since that will require also covering how to select suitable feedrates or we risk someone just using whatever the machine is currently set for with possibly harmful results.

Facing off
  • Crude positioning using the main slide, then actual job done on the cross and top slides
  • Lathe mustn't be stopped with the tool in the work
  • Show how to touch on then zero dials and advance suitable amounts, what is a suitable amount?
  • Remembering to compensate for backlash in all 3 slides
  • Smooth even movement using 2 hands on the slides.
  • Cover listening to the tool and the machine, grinding noises or audible loading of motor are seriously bad
  • Wind in to just past the centre and then out again
  • Cover going slower near the centre and what it means if there's a nub left or the tool tries to ride up (tool height wrongly set).
  • Cover warning signs of very bad chip form(all materials) and colour(steels)
    • Discrete small chips with a slight yellow colour are best, silver is fine, blue is too hot for HSS.
    • Long ribbon swarf although not ideal is acceptable, very small chips, dust, or "vanishing" chips are rubbing and NOT OK.
  • What a nub means and what the shape of it tells you
  • Roughing passes and a finish pass.

Covering the very basics of Facing off

Parallel Turning
  • Picking the correct slide for the length of cut, positioning correctly at start of cut.
  • Touching on and zeroing dials.
  • Smooth even progress using 2 hands on wheel.
  • What good chip form looks like.
  • Reasonable depth of cut for roughing.
  • Accurately stopping at the same place on multiple passes.
  • Coming to an accurate diameter and depth of shoulder
  • Limitation on doing long cuts (can't do them at this induction level) or working on small diameter workpeices (need for much shallower cuts and care over tool forces)
  • Finish pass and cleaning up the shoulder.

Basics of Parallel turning

Drilling
  • Mounting the drill chucks in the tail-stock.
  • Maximum drilling capacities for each chuck.
  • Selecting suitable drills for the material.
  • How to move and position the tail-stock
    • How to lock it off
    • How to advance the quill.
  • Selecting suitable speeds using the table on the wall (2 flutes so 50%).
    • Using centre-drills to start the hole.
  • Maximum drilling depths is 5x diameter
  • Using the dial on the tail-stock to pick a depth
  • Depth from tip and depth from shoulder drilling.
  • Feeling for suitable feed rates and the symptoms of too little/too much feed pressure
  • Watching out for thermal issues, flood coolant preferred.
  • Coolant is non-corrosive and doesn't need to be wiped off after
  • "Pecking" drill pattern.

Using a drill safely and to the target depth

Parting off
  • Using the HSS parting blade only at this level
  • Setting tool stick-out, cover maximum parting depth based on the tools protrusion and absolute max (20mm depth of cut), Checking tool height
  • The need to ensure very accurate perpendicular tool positioning and precise and very even movement.
  • Parting should be done at less than 35% spindle speed compared to other cuts and why that is
  • Use of copious cutting lubricant and frequently reapplied or ideally the flood coolant.
  • Riding the boundary between slip-start and continuous cutting

Ideally people should be able to do this to use the lathe properly but induction level-1 shouldn't cover grooving or use of carbide

Cleaning
  • No workpiece left in, no tool left mounted, nothing in tailstock
  • Picking up swarf, watching out for sharp edges and cuts.
  • Draining swarf if you've used flood coolant.
  • Where to put the waste swarf.
  • Wiping down the machine and especially the bed, reoiling after wipe down if heavy cleaning was needed.
  • Cleaning the guard
  • Mopping up any spilled coolant
  • Don't expect the lathe to be left spotless, just all the swarf gone

Keeping the Lathe clean!

Level 2 Induction

This one is to cover people who intend to seriously use the lathe in an upcoming project but who don't need to handle complex or detailed work so quite a bit of what was previously level-1 induction will now appear here. Level-2 induction requires people have completed level-1 induction first and and is broken into 2 modules of 2 hours each.

Module 2A

Topic Detailed contents Rationale
Use of cutting fluids and other lubricants
  • Using the 3 types of cutting lubricant, the liquid, the gel, and the flood and when each is used, Avoiding fling and mess using the gelled lubricant, using the liquid when deeper penetration is needed to reach cutting faces.
    • Use of proper lubricants for aluminium (the CT-90 is "Universal" and can be used)
    • Using the flood coolant system
      • Checking coolant level and topping up if needed, the warning light only reads accurately on start-up
      • How it affects cutting speeds
      • Avoiding spray
      • Cleaning machine after use.

Proper cooling extends tool life, allows deeper faster cuts and helps keep machine clean

Materials selection

More advanced materials and how to work with them, all materials allowed at level-1 plus

Aluminium OK with proper lubricant
Acrylic/Polycarbonate/Nylon/ABS Needs razor sharp tooling so freshly ground steel may be beat carbide and the need for short cuts and breaks and watch out for heating especially on polycarbonate
Wood Only if there's a LOT of extraction to keep dust off the lathe
Cast Iron Yes, slow speeds, warn of magnetic hazardous dust, first cut must be deep
Stainless Steel Yes with carbide tooling, warn of work-hardening and the need not to be too gentle , need for coolant for good results

Next step up on materials

Advanced work-holding using 3-jaw
  • How to change the jaws, winding them out to release, maintaining number order, getting new ones engaged in proper sequence. Making sure the jaws are left fully engaged when you leave or it's dangerous for others.
  • Using it to grip inwards on the regular jaws, gripping outwards on thick-walled tubes/rings using alternate jaws, gripping inwards on large objects using alternate jaws.
  • Using internal supports for delicate materials, warn that the small steps on jaws grip less strongly and will require smaller depth-of-cut for roughing.
  • Using dial gauge and shims to accurately align parts in the 3-jaw.
  • Continue to emphasise that only the minimum possible protrusion from the chuck should be used.

Not covering gripping large/thin-walled/long things that will require steadys until intermediate

Switching between 3-jaw and collet chucks and when to use each
  • Use the bed protector at all times.
  • Toecap boots a good idea when changing chucks.
  • How the camlocks work and who to call if they're out of spec, even tightening, alignment marks, where the chucks are kept.
  • Keeping the nose and taper spotlessly clean.
  • How the 3-jaw is quick and easy but doesn't hold concentrically, how the collet chuck does but only grips smaller objects. Collet chuck is preferred for materials that it can hold.
  • Making sure Lathe is left with 3-jaw fitted with it's jaws set in inward-gripping mode and correctly balanced must always be left in the lathe when after you're done.

These 2 cover everything that's needed for beginner training

Using the collet chuck
  • Changing the collet and respecting the keyway, tightening up evenly and remembering to take the key out.
  • No speed limit on this chuck but can hold round or hex bar only.
  • Holds concentricity accurately and work can be removed and replaced repeatedly.
  • Grips tighter than the 3-jaw on the same material but can also use internal supports for delicate objects, but the minimum grip depth must be respected.
  • The 3-jaw must be put back in when you're done

Just general use like the 3-jaw

Using the Tailstock
  • Live and dead centres, when to use each & speed limits.
  • Dead centres must be lubricated, live centres should not be
  • Drilling centers and using them to steady workpieces.
  • Making sure of clearances around the tools and slides when using the tailstock.
  • Use of tailstock allows turning of parts length to up 10x diameter.

Expands the range of objects that can be worked

The 3 tool types
  • HSS/Tungsten-Steel tools are robust, easy to use and can be reground indefinitely but are limited by temperature and best used with copious coolant/lubricant if making heavy cuts.
  • Brazed carbides can be sharpened to a razor edge and take fine cuts but are the most brittle and although they can be resharpened we can't do it at the lab, they have to be sent away.
  • Cemented carbide insert tools are hard, wear-resistant, usually have a anti-friction coatings, they're less brittle than brazed carbide but still chip easily but paradoxically hate being used too gently, because of their coatings they're not as sharp as the others.
  • Carbides must never EVER be stopped inside work, and cooling should be flood or not at all, never intermittent.
  • Using the wall chart to select the proper spindle speed for each tool/material combination

Need to know the proper tool for each job

Tool Inspection
  • Checking the tools with the inspection microscope, what good and bad looks like on each of the 3 tool types.
  • Recognising wear and polishing on HSS tools and when it's OK and when the edge had been lost.
  • Looking for wear or more likely chipping on brazed carbide, the procedure for getting them re-ground if they need it.
  • Inspecting inserts, recognising the colour change where the coating has been worn off, looking for chips on the edge and working out if they're going to affect your work and if the insert needs changing, looking if the chip-breaker is still OK or is clogged/worn.
  • Letting people know that breakages are inevitable and although we should try to avoid them, but they're not THAT expensive when they happen.

Bad tools will give bad results!

Changing carbide inserts
  • Where the torx keys and new inserts are kept, releasing the old insert and disposal/Recycling.
  • Thorough cleaning of the insert seat including a solvent wash if needed and cleaning the screw-thread.
  • Examining the holder for condition and damage.
  • Using the supplied bolt, substitutes are NOT allowed.
  • Handling the inserts carefully and avoiding being cut by them, inserting in proper orientation, screwing down with a suitable level of force.
  • Checking using the microscope that it's seated properly and ready for use, checking for insert snugness.
  • If you just broke an insert, checking the workpeice for carbide fragments.

At this level we can expect people to change an insert, but not to grind their own tooling

Tool shapes for various operations
  • The different tools we have focusing on the carbide insert ones, covering Roughing, Finishing, Shoulder, Beveling, Parting, and Boring.
  • Do not including grooving, knurling, threading, or custom profile tools.
  • Describe how they are used and for what operations, cover the effects that support or lack of and size and angle of tip have on strength and depth of cut that can be done.

At this level people should be shown how to do a wider range of operations and the tools they require.

Differences between roughing and finishing
  • Roughing removes bulk material rapidly, for getting parts down to approximate size and shape.
    • Cuts can be large and fast within the capacities of the lathe and tooling.
    • Is usually done with copious coolant and care must be taken not to cause excessive distortion of workpeice or tool
    • No consideration is given to surface finish
  • Finishing brings the part to final size and gives a higher surface finish
    • Are done at higher speeds
    • Cuts are smaller although you need to be aware of minimum cut sizes using the carbide insert tools
    • Coolant may or may not be used but cutting fluid should be.
    • Finishing cuts are also used on small workpeices or when the tools are far-extended to reduce cutting forces.
  • Using the wall chart to pick the proper spindle speed, note that flood coolant increases allowed speed 20%.
  • How chip type changes with speed and DOC, mention how the different types of swarf are formed and how to change from one to another.
  • Reiterate the signs of rubbing and what to do about them.

Covering the 2 basic types of cut and when to use them

Using the slide locks
  • Locating each of the slide locks, how you use them when parallel turning and facing to get smoother and more accurate cuts.
  • Using them to avoid accidental moves when working but caution that leaving them on will cause instant damage to lathe if the power-feed on that slide is engaged.

Accurate surfacing

Selecting Feeds and Depth-of-Cut
  • Chip loading and how it affects chip form
  • Normal depths of cut for HSS/Carbide tooling and typical feed rates that should be used. The values listed here are deliberately conservative and faster material removal rates may well be possible depending on circumstances, as always, listen to the lathe, watch the chips and adjust speeds and feed accordingly.

These tables are under development and will be expanded in time, till then, use your best judgement

Typical Depth of cut (DoC) and Feeds for carbide insert tooling
Material Depth of Cut Feed (mm/rev) Notes
Aluminium (roughing) 1mm+ 0.2mm+ Even roughing gives a smooth finish
Aluminium (finishing) 0.1mm - 0.5mm 0.05mm - 0.10mm Glassy finish
Mild Steel (roughing) 0.4mm - 1.0mm 0.05mm - 0.20mm Can be a bit rough surface
Mild Steel (finishing) 0.1mm - 0.3mm 0.03mm - 0.06mm Use facing tool for best result
Stainless Steel (304) (roughing) 0.3mm - 0.5mm 0.10mm - 0.20mm Produces long ribbon swarf
Stainless Steel (304) (finishing) 0.07mm - 0.12mm 0.05mm - 0.10mm Can give almost mirror finish
Titanium 0.3mm - 0.6mm 0.06mm - 0.12mm Requires level 3 induction as titanium has additional safety hazards, requires a brand-new insert and special turning technique

Cutting efficiently without breaking tools!

Using the power feeds
  • How to read the tables on the lathe to work out proper feed rates using the left columns of the bottom table.
  • Changing the gears to select the chosen feed rate should be done while the lathe is not running, if you can't get a gear, go back to a gear you could get, then run the lathe for a few seconds and try again. Changing gear while running is allowed only at speeds 540rpm and below
  • Verify that the direction of cut lever on the headstock is correctly set.
  • Check which slide is being fed, remembering that the feed rate is halved on the cross-slide.
  • Checking the powerfeed rod is clear of obstructions, checking you can move the tool through the entire intended range of motion without hitting anything.
  • Position the tool well clear of the work and do a test move on the powerfeed to verify that it's moving in the direction and at the speed expected.
  • Position the tool at the start of the cut, and touch on using the cross-slide zeroing the dial.
  • Pulling out the main feed wheel to disengage it if desired, and then beginning the cut using the powerfeed
  • Disengaging and finishing the cut using the cross-slide and then re-positioning back to zero for the next cut.

Using the powerfeeds for larger cuts is almost essential but proper settings must be chosen to avoid breaking tools

Module 2B

Topic Detailed contents Rationale
Taper Turning on top-slide
  • Setting the angles on the slide and locking it down, setting the tool angle to be compatible with that cut direction.
  • Using the cross-slide to advance the taper and how to calculate distances when the move isn't perpendicular to the cut.
  • How tool speeds vary across the travel of a taper, similarly to facing off and hence requiring variation in feed rate.
  • Watching out for clearances and how to deal with if the tool winds up in a position where the cross-slide fails to engage over full range, difficulties using live/dead centers with taper turning.
  • The travel limits on the top-slide, and the possibility of using tail-offset turning for those who want level-3 induction. Using back-side cutting to deal with awkward angles
  • Putting the top-slide back parallel when you're done with the Lathe.

Putting tapers on work

Using taps and Dies
  • Taps
    • Semi-profile and full profile, taper-second-plug types, correct drill sizes.
    • Holding in the wrench, using the dead-centre to steady and align
    • Proper lubricant using the gelled or liquid CT-90
    • Chip-breaking pattern on use (1 in, 1/2 out)
    • Care to avoid cross-threading
    • Feeling for proper depth on blind holes
    • Caution about brittleness - your workpeice is lost if you break a tap
    • Cleaning off when done.
  • Dies
    • The flush and taper sides, using closed and split dies and the advantages of each, correct rod sizes.
    • Holding in the wrench and adjusting split dies.
    • Being even more careful about proper alignment, hard to start sometimes.
    • Holding in the tailstock holder, proper lubrication, chip breaking, cleaning

Tapping and threading are pretty common operations but with the brittleness of the tools there's quite a few gotchas people need to be warned about, so it's neither level-1 nor level-3

Boring
  • Different sized boring tools, different end profiles and the types of hole bottoms they produce.
  • Minimum initial hole sizes for the boring tools and how they rub if it's not met, raising the cut line only if vital. Using the very large MT3-shank drills in the tailstock to opening out the holes large enough. Using milling cutters held in the tailstock to produce a flat-bottomed starting hole.
    • Using the largest boring bar available that can fit in the hole
  • Working out the minimum tool exposure necessary for the job and adjusting the boring bar suitably.
  • Noting the drill depth accurately and touching on to the bottom of the hole.
  • The need for relatively gentle cuts because of the reduced stiffness of the tooling. The use of sharper than usual tooling with more-than-usual rake angle to reduce cutting forces.
    • The need for (possibly multiple) spring passes owing to reduced rigidity
  • Using the dials to set the depth and calculating depth using cross-slide for tapered holes.

The need to produce holes of odd or very large sizes

Breaking corners
  • Why it's needed - avoiding cuts from sharp work, taking off burred over corners.
  • Using the top-slide to cut tapers
  • Cutting using the side of tools and especially the grooving/beveling carbide insert too while watching the angles that are produced by the 55deg carbide.
  • Note when using the carbides on a parallel motion that the depth of cut increases very rapidly with sideways motion so considerable caution is needed if beveling deeply

Important safety and aesthetic technique

Parting off
  • The need to ensure very accurate perpendicular tool positioning and precise movement.
  • Parting should be done at 15-30% spindle speed compared to other cuts and with the use of flood cooling, carbide needs a minimum speed for chip-breaking
  • Making sure that minimal tool is exposed on the blade holder.
  • Breaking corners during parting and jogging the breaking cutter using top-slide and it's dials to reset position.
  • Methods of catching the parted object, using a magnet, using a drill or rod, never fingers.
  • Caution for tool chatter, check rigidity and protrusion, slowing down if needed.
  • If the parting is done well then re-facing the back of the part may not be needed

Parting neatly is needed for work at this level

Turning using indicator dials
  • Touching on and zeroing the indicators, using them to position the tool even when you can't see it, for example when using a boring bar or with heavy coolant.
  • How the main slide looses the zero point on the top-slide whenever use and how to approximately regain it by re-touching on.
  • How the angle of the top-slide changes the X/Y position effects of that dial, the trigonometry to deal with that.

Basic use of the dials will have been covered in level-1 induction but a deeper understanding will be needed here for boring and flood cooling.

Polishing using emery cloth/paper and files
  • How to hold it being very aware of the position of the chuck and it's jaws to avoid injury and how it's a lot safer if you're using the collet chuck.
  • Being careful of the paper/cloth getting caught and dragging you in and never using fingers for polishing internal surfaces.
  • Possibility of using a long length of emery cloth in order to get more reaction time if things go wrong
  • Suitable speeds for the work, patterns of movement to get good effects. How to choose suitable grades for the job at hand, changing through finer grades as you progress.
  • Cleaning the work thoroughly when changing grades and making sure to use the bed protector.

People are going to do this, so we might as well make it as safe as possible

General oiling
  • Which grade of oil to use ( ISO 220 ) and where on the slideways the oil should be put.
  • Oiling the chuck but keeping the oil off the gripping surfaces, oiling the power-feed and leadscrew.
  • Leaving slides covered by the toolpost to reduce lube loss
The more people helping with this the better
Refilling apron oil Checking the sight glass for level, where the fill and drain plugs are, using the proper grade of oil (ISO 68) and when to fill it up, how much to use With the one-shot in use this will need to be done often

Level 3 Induction

Requires Level 2 induction to be completed first as there's a lot of material to cover on this one so don't want to be going over basics again. People don't have to do the entire level 3 course, and in fact we don't recommend it as covering all of this would take several days and your brain would be about ready to melt by the end of it! Individual topics can be done as needed, the content of this course isn't finalized yet so we're not ready to run it as a full course but if you're specifically interested in one topic then contact a induction provides who offers level 3 to plan out and arrange a short session on that topic.

Level 3

  • Internal and external thread-cutting with insert tools including multi-start and worm gears
    • Theory of thread-cutting
      • Thread forms and how they change with size
        • Which bits are critical and which aren't
        • Extra reliefs needed for worm gears to mesh nicely
      • Helix angles and how numbers starts alters this
      • Relief angles needed
      • Problems of setting suitable speeds
      • What wrong speed or insufficient rigidity looks like
    • What tools are available
      • Semi-profile, full profile, and why neither will work well for multi-start
      • The option of grinding your own
    • Setup for thread cutting
      • Creating gullies
        • Creating external gullies using parting tool if you have to but effects of stress risers
        • Using the thread tool to make internal gullies
        • What to do if there's not room for a gully
          • You probably shouldn't be thread-turning, look at specialist taps/dies
          • Using reverse-side thread-cutting
          • But if you REALLY have to.... using back-out strategies and the foot brake
      • Reading the tables to set gear suitably
        • Using the change-gears for really coarse threads
      • Setting up the threading dial for metric threads
        • Why it won't work on imperial threads
      • Tool mounting and angle
      • Choice of top-slide angle and setting feed angle on the top-slide
      • Picking speeds that will work
      • Using threading dial or using back-and-forth patterns
      • Choosing infeed amount and using trig to calculate theoretical depth
      • Using wire thread gauges to check depth
      • Test fitting if possible
      • Deburring when done
  • Blind turning on the indicator dials
  • Grooving Internal and External
  • Grinding tools/Profile turning
  • Decoding carbide insert type codes
  • Knurling (calculating diameters for an even knurl)
  • discontinuous turning
  • Altering the change-gears and speed limits (540)
  • Very large workpeices, faceplates and speed limits
  • Using fixed and travelling steadies for very long workpeices
    • Why to use steadies
    • How the 2 types grip and stabilise your work
    • When to use Fixed Steady
      • Choosing location, have to make a flat to rest on
      • Installing
      • Tightening and lubricating
      • Keeping chips out with shields
    • When to use travelling steady
      • Positioning
        • Ahead - Stable but risk of transferring out-of-roundness and wearing brass blocks
        • Co-incident - Strongest but hard to do and risk of chips getting dragged in
        • Trailing - Roundness is stable but risk of longitudinal oscillations forming
    • Burning in the brass blocks
      • It's going to happen anyway, might as well make it happen when and where you choose
  • Using the dial indicator to maintain position on complex cuts
  • Calculating feeds&speeds for other materials not on the standard table
  • Cutting standard module worm gears
  • Pressure-plate turning of plastics
  • Offset work mounting
  • Mounting the large toolpost and setting it up
  • non-round work
  • Cleaning and oiling the lathe including oiling points
  • Changing oil for the lathe
  • Advanced materials - Titanium/Magnesium alloys/HSS (We don't keep the necessary materials in stock, but if inductee provides it these modules can run)
    • Titanium
      • Grades of titanium available, unless otherwise specified Ti6Al4V is the most common
      • Properties of titanium and how they affect turning
        • Poor thermal conductivity - Rapid heat buildup and critical need for coolant
        • Heat goes into material, NOT chips - Even worse heat build up
        • Thermal hardening, if you let heat build it'll harden and become un-turnable
        • High toughness, Steel tooling is possible if razor sharp but carbide is preferred, brazed carbide can be very effective
        • Flammability, swarf is a serious danger
      • High toughness and tendency to hardening means low tool speeds are required, 15m/min is a common choice
      • Excellent set-up rigidity is vital, use centers or steadies wherever possible, be very aware of work and tool stick-out and tool position relative to the slides
      • Normal cutting depths, 0.5mm for roughing, 0.3mm for finishing, DON'T try to take skim cuts if you can help it
        • Spring passes are to be avoided unless vital, and if they are vital be aware you'll only get to make one spring pass before the work is too hardened to turn any further
      • Feed rates, 0.1mm/rev is a good starting point, but experiment and watch your chips closely
        • Chips probably won't break no matter what you do, aim for tight curls, beware of birds-nesting as it's a serious fire risk
      • Avoid discontinuous cuts if you possibly can, they're very damaging to tools
      • Cuts must be decisive, you must not dwell with tool in contact with work, rubbing causes rapid hardening
        • Cuts should be done using power feed whenever possible as it's hard to achieve proper evenness manually
        • Cuts should enter at full speed, no gentle lead-ins
        • Once cut completes then the tool must be backed away from the work immediately, it cannot rest at the end position, not even for a second
      • After every cut, remove the swarf to a safe location where it can't be ignited from the work, and inspect the tool
      • Drilling Titanium
        • Uncoated HSS are often ineffective
        • TiN/TiAN coated drills are OK
        • Cobalt or Carbide drills are best
        • Peck drilling is essential as it's impossible to cool the drill tip effectively
        • Pecks must be small (2.5mm or 0.5 x drill diameter, whichever is less)
        • Drill must be fully withdrawn between pecks to be cooled by the flood coolant
        • Check for work heating every peck
        • Watch your chips carefully and re-sharpen the drill the moment there's any sign of degradation.
      • Parting off is possible with carbide tools, but only if the center is drilled, full-depth parting is difficult
        • If the part-off is deep it may be necessary to change spindle speed during the operation.
    • Magnesium
    • HSS/Hardened materials
      • Hard-turning can be used to produce hard items at a precise final dimension without having to allow for distortion during heat treating
      • Some reduction of surface hardness will occur, the faster the turning the less pronounced this will be
      • Checking the workpeice hardness using the ultrasonic tester
      • Hard material turning is normally done without coolant
      • Swarf will come off HOT, depending on circumstances maybe up to red-hot
      • Rigidity of set-up it vital, pay special attention to stick-out and tool position relative to the slides
        • Lock any slides you're not using
      • Examine the toolholder carefully when fitting a hard-turning insert, all parts must be in excellent condition or be replaced.
      • Hard turning requires relatively high spindle powers, be sure not to overload and stall the lathe
      • Tool destruction is certain if it's allowed to stop in contact with the work
      • Tool chipping is certain if it's bumped into the work during setup
      • Inspect tool after every pass
      • Moderately hard steels can be turned with higher grade carbides
        • Suitable hardnesses range up to around 45-55HRC
        • Swarf will come off very hot and may spark - take suitable safety precautions!
        • Depths of cut and feed rates should be low, ideally <0.2mm
        • Surface speeds around 30-50 m/min
      • Very hard materials can be turned using CBN inserts
        • CBN Inserts are expensive and delicate, they must be treated with extreme care
        • Maximum hardness ranges up to about 65HRC but values above 55HRC will cause rapid tool wear
        • Swarf will come off up to 450C - take suitable safety precautions, consider how you're going to stop the machine if burning-hot swarf is spraying over the controls
        • Breaking a chip is unlikely, expect birds-nesting
        • Depths of cut and feed rates should be low, ideally <0.1mm
        • Surface speeds around 50-75 m/min, the harder the material the slower the cut but go as fast as possible for any given job, CNC machines can run faster than this but our set-up won't allow it.
      • Diamond tooling exists for use in hard non-ferrous materials and highly abrasive materials
        • Diamond tooling comes in PolyCrystaline Diamond (PCD) which is very expensive - more so than CBN, and MonoCrystaline Diamond (MCD) which is eye-wateringly expensive.
        • PCD is very, very hard, MCD is the hardest tooling material known to exist.
        • Diamond tooling cannot be used on ferrous metals as the carbon from the diamond will dissolve into the iron
        • Diamond can be used to turn exotic materials such as aluminium superalloys, nickle superalloys, precious metals, tungsten carbide and carbon fiber
        • Maximum work hardness for diamond tools can go as high as 70HRC although wear increases above 60HRC
        • Cutting speeds can range up as high as 1000m/min or as low as 10m/min depending on the hardness of the work
        • Depths of cut and feed rates should be low, ideally <0.1mm, however the very high surface speeds used with PCD tooling will still result in rapid material removal rates
  • Workholding using all chuck types and recovering concentricity
  • Using reamers
  • Turning between centres
    • Why you might do it
      • Improved concentrically and repeatability
      • Holding awkward shapes
      • Reusing centers on existing parts or that someone else cut
        • Recutting a center if you need to (toolpost support trick)
    • Setting up a center and a catch plate
      • Installing a center in the headstock
      • Installing the catch plate
      • Picking a suitable dog size, setting it up so it won't slap
        • Caution about over or undertightening
      • Alternatively making a center on stock held in a 3/4 jaw chuck
      • Live or Dead center at the tailstock?
      • Might require the use of steadies if the part is long
    • Turning between centers
      • The dog and catch plate will cause imbalance so watch speed
      • Parts may be very long so watch out for flex
        • Use support if needed
        • Take shallow cuts
    • Tailstock offset turning
      • Regular centers only for the smallest of offsets
        • Part distortion if used too much
      • Using ball-bearing centers for larger offsets
      • Resetting the tailstock alignment when done, high precision required
  • Making and shaping brazed carbide cutters

Maintenance

Doesn't cover actually using the lathe at all, covers all the maintenance jobs that lathe might need apart from stuff that requires specialist tooling we don't have or factory assistance

Topic Detailed contents
"Maintenance in progress" sign Putting the sign on the lathe if you need to leave mid-maintenance
Cleaning General clean-down, all the surfaces that must be done including hidden ones and inside the change-gear case. Use of solvent to clean and possibly at some point if we get some then use of touch-up paint.
Checking tightness Checking the tightness of the various exposed bolts and fasteners including the changegear mountings
Surface oiling Wiping down all surfaces with a thin skim of ISO-68 oil after cleaning, oiling the leadscrews
Checking oil tanks and draining/refilling Location of the sight-glasses, fill point and drain points for all 3 oil tanks, which grade of oil goes in which and how much. Main tank takes 1L of ISO68, screwcutting gearbox takes 0.5L of ISO220, Apron takes 0.3L of ISO68. Disposal of used oil ( How do we handle this? )
Oiling points Applying oil using the high pressure oil can to all the oiling points listed in the manual, including the ones under the changegear case
Oiling the changegears Opening the case, oiling them, do not bypass safety to run the gears while oiling
Checking and adjusting play in mainslide Measuring the play with the dial-indicator at the 3 relevant positions, how to unlock and adjust the grip clamps, how little they need to be rotated, rechecking with dial gauge, what proper adjustment feels like
Checking and adjusting play in cross-slide Proper points for checking the play, how to release and adjust the wear strips
Checking and adjusting Backlash in cross-slide How to measure the backlash, and how to release and adjust
Checking and adjusting play in topslide Measuring the play, which grubs screws adjust the wear strips
Checking play in spindle Check only, adjustment is a back-to-factory job!
Cleaning and re-lubing the chucks How to disassemble and clean the 3 and 4 jaw chucks and which parts must and must not be lubricated
Keyless drill chuck Disassemble and clean the keyless Chuck, which parts to oil and which parts must be kept dry
Flood cooling system How to check the fluid, clean and change if needed
Update Wiki Make entry indicating you've performed maintenance, update status if there's a change