Lathe

Lathe

A metalworking lathe, the design is based on an Atlas.
Equipment Information
Status	Unknown
Manufacturer	Sphere
Model	6" Lathe
Hackspace Information
Induction Required	Yes
Induction Information	Here
Card RFID Enabled	No
Owner	Hackspace & Members
[More Info]

Disambiguation: Are you looking for the Wood_Lathe?

The Basics

We have a 6" Sphere lathe - the design of which is based on a 6" Atlas - with a 0.5 hp motor.

Our lathe is suitable for turning metals and plastics. Aluminium, brass, copper, delrin/acetal and nylon shouldn't present any problems. It should be possible to machine mild steel too, though you may find some additional cooling is necessary.

Both the carriage and cross slide can be power-fed using the appropriate change gears and the feed-direction gearbox on the left-hand side.

We are currently lacking a full set of change gears and a threading dial.

Induction

For an induction you should ask Joe or Nav either in person, via the mailing list or on IRC.

Safety

• You must be inducted before you can use this machinery.
• Long hair MUST be tied up, long sleeves should be rolled up securely.
• Eye protection MUST be worn. Safety glasses are in the "Safety Equipment" box.
• The chuck key MUST be removed from the chuck before the lathe is turned on.
• Gloves MUST NOT be used whilst the machine is on - if you are concerned about grease and oil use barrier cream.

• The emergency stop button is located below the "Start" button.
• Ensure the work is securely fixed in the chuck.
• Keep the change-gear door shut whilst the machine is on.
• Swarf is sharp, keep an eye on it. Don't let it build up into birds-nest piles underneath the chuck.
• Use a centre drill on work before using a normal drill. The bit will wander and could break if you don't.
• Don't change the lead screw gearbox position whilst the machine is running.
• Go and check you removed the chuck key again.

Maintenance & Care

Oiling

The lathe must be oiled before each use. Without oil the bearings will run dry and ruin themselves and the ways will wear and become scored and inaccurate.

Refer to the oiling chart here which is both here and beside the machine before use. If you aren't sure, ask.

The oil currently used is "Machine & Slideway Oil". If the bottle runs out let someone know so it can be replaced.

Tapers

The spindle taper (MT3), tailstock taper (MT2) and any tooling which fits into them must be free of oil, rust, dirt and grease to lock correctly and securely. Give tooling a wipe down with clean tissue before inserting it into the taper hole to prevent damage.

Sanding & Grinding

If you are sanding on the lathe make sure that you cover the ways with cloth or paper and clean up comprehensively when you are done - including the chuck. Magnets are available to securely hold protective material down so it won't be blown into the chuck.

This is very important: the dust generated by sanding and grinding is very abrasive and will wear the ways quickly, turning the precision machinery we have at the moment into a sloppy, inaccurate pile of scrap metal.

Tools

We currently have:

• A selection of carbide tipped tools
• 2 x 13mm drill chucks and a live centre for the tailstock
• Centre drills
• Knurling tool (on loan)
• 4-Jaw Independent Chuck
• 3-Jaw Self-Centring Chuck
• 6-inch Faceplate

We'd like:

• A full set of change-gears

Insert tools

The inserts taken by most of the lathe tools are 80 degree rhombus style - you can use CCMT 09 or CCGT 09 marked tools. Shiny silver coloured inserts are for use with aluminium, the matte gold coloured ones are for use with steel. There are some exceptions, but this is a good rule of thumb.

The inserts are held in place with a Torx screw. When swapping types be aware that you might have to re-centre the tool height using the quick change tool post screw facility.

It is still a good idea to learn how to grind a HSS tool.

Back Gears

The locating pin is on the front of the bull gear. It is black and in the centre of this image.

The lever in this position is disengaged. Rotate towards the spindle to engage the back gears.

Running the lathe using the back gears allows slow spindle speeds for threading and turning large diameters.

There are two steps to setting back gear mode - the lever on the right hand side of the headstock and the plunger on the bull gear inside the headstock.

• You MUST NOT attempt to run the lathe with the plunger "in" and the back gear lever engaged.
• There are particular oil points that must be attended to when using the back gears.

Engaging the back gear

• Loosen the drive belts.
• Open the top of the headstock and rotate the spindle by hand until the plunger is visible.
• Pull the plunger out. You might find it easier to use a small flat blade screw driver to gently lever it out.
• Pull the back gear lever towards the headstock to enable the back gearing. You might need to rotate the spindle by hand slightly to allow the gears to mesh.
• Turn the spindle by hand to ensure that nothing is binding.

Disengaging the back gear

It's polite to leave the spindle in direct drive mode when you are finished with the lathe.

• Push the back gear lever away from the headstock to disable the back gearing.
• Open the top of the headstock and rotate the spindle by hand until the plunger is visible.
• Gently push the plunger and use the belts drive system to rotate the pulleys until the plunger locates itself in its hole.

The Lead Screw

Leadscrew gearbox controls

Power to the (8 TPI) lead screw is controlled by a small gearbox to the left hand side of the lathe. There are three positions the lever can be in:

• Left: Carriage moves towards headstock, cross slide moves outwards.
• Middle: Neutral. The lead screw will not turn.
• Right: Carriage moves away from headstock, cross slide moves inwards.

When you are not using the lead screw, put it into neutral. Ensure that each position is selected definitively using the detents in the gearbox casting otherwise you may find the lead screw stops turning partway through a cut.

If you find that you can't move one of the axes of the machine check that the relevant power feed lever hasn't been engaged.

Carriage feed

Apron controls

Carriage motion (along the bed, left and right) is controlled by the half-nut lever on the right hand side of the carriage apron.

• To engage the half-nuts rotate the half-nut lever approximately 90 degrees clockwise
• To disengage to the reverse.

Cross slide feed

Cross slide feed is useful on long facing cuts and, if you are brave, when parting off.

• Pull out the plunger underneath the cross slide handle to engage cross-feed.
• Push the plunger in again to disengage the cross feed.

Selecting a spindle speed

Belt position diagram

The motor runs at 1420 RPM and there are two belts you can change to select a spindle speed. The belt from the motor to the countershaft has two positions and the belt from the countershaft to the spindle has four.

For general turning you should refer to a suitable machinist's book (or the internet) to find an appropriate spindle speed. As a general rule, the harder the material you are turning the slower the cutting speed.

The belts must be run straight from one set of pulleys to another and not offset.

All speeds below are in RPM. Source

Direct Drive
Spindle Belt	Motor Belt
	A	B
1	380	975
2	540	1380
3	835	2150
4	2285	3050

By enabling the back gear function the speed of the spindle can be reduced (and thus the torque increased) to a speed useful for threading, turning large diameter pieces and parting off.

Back Gear
Spindle Belt	Motor Belt
	A	B
1	55	145
2	82	310
3	125	415
4	185	463

Work-holding

There are a variety of ways to hold work to be turned in the lathe. At the Hackspace we have a 3-jaw and a 4-jaw chuck available for use.

The spindle nose is threaded (8 TPI, 1.5" major diameter thread) and should be cleaned every time the chuck is changed. Similarly, the female chuck thread should be cleaned before each use.

Don't assume the previous user has cleaned it well enough!

When threading the chuck onto the spindle nose do so gently but firmly - there is no need to 'snap' the chuck onto the last section of the thread. When unscrewing the chuck from the spindle do so carefully: it will come off the last thread very suddenly and you could drop it onto the ways. This has already happened a few times in this lathe's history (there are a few dents on the ways under the spindle) but it would be great if it didn't happen again!

Spin the chuck by hand before you turn the power on to check that nothing will collide at high speed and of course always, always ensure that the chuck key has been removed to prevent injury to yourself or other people and (most importantly) damage to the machine.

3-Jaw Chuck

The 3-jaw is the easiest to use, but it's also pretty inaccurate and will only get more inaccurate over time.

If you ever take the chuck apart for cleaning keep in mind that the jaws are numbered (1, 2 and 3) and they each fit into their respective slots in the body and must be inserted onto the scroll in that order. If you don't they won't meet in the centre and you'll have to start from scratch!

4-Jaw Chuck

If you are working with a part which has already been machined (or you haven't got much spare material, diameter wise) it's important to get the work running as 'true' as possible.

The 4-jaw independent chuck can, with a bit of effort, be fine tuned to hold the work very concentrically. For more information see this short (3 min) video. There are two chuck keys for the 4-jaw.

If you want to deliberately off-set the work to turn an eccentric feature this is also very easy with the four-jaw.

Faceplate

A faceplate allows you to turn oddly shaped work and to give reliable drive power to work being turned between centres using a lathe dog.

Useful References

• The Bible of Metal-Working with a Lathe
• Plain Turning on the Metal Working Lathe
• How to machine a shaft at two different diameters
• How to Shape Lathe Cutting Tools (also covers tool height adjustment)
• How to Cut a Fine Thread on a Lathe
• Tubalcain channel - The Machine Shop Tips series is really useful
• History of Atlas lathes

Tooling Wishlist

• Inserted parting/grooving tool

Parts

Compound gibbs grub screws: BA2 x 20mm

Lead Screw Gears

Bevel Gears have been stripped, see gallery https://goo.gl/photos/dEsoEQSFsnoNmm1H7

Risk assessment for use of Myford lathe.

Hazards.

• 1) Chips in eyes.
• 2) Hair or clothing caught in rotating parts.
• 3) Cutting tool breaking or getting ejected from holder.
• 4) Sharp objects and chips cutting fingers.
• 5) Dropping heavy parts.
• 6) Objects ejected from chuck.

Persons at risk.

• Operator.
• Persons nearby.

Initial assessment of risk.

Hazard identified	Severity	Probability	Risk Factor
Chips in eyes	3	2	6
Hair or clothes caught in chuck	2	2	4
Hair or clothes caught in belt drive	2	2	4
Cutting tool breaking	2	2	4
Cuts from sharp objects	1	3	3
Injuries from dropped objects	2	2	4
Objects ejected from chuck	1	3	3

Control measures.

• Users will be required to go through an induction with Nav or Aiden.
• Safety glasses will be worn at all times.
• Check everything is secure before starting the motor.
• Users will be trained to mount the cutting tools and work pieces safely.
• Guard in place over exposed drive belts
• Ensure long hair is tied back, ties not to be worn and loose clothing secured away from belts and chuck
• Always use a brush to clean away chips and swarf.
• Operators to ask for assistance when moving heavy objects.
• Operator to ensure floor of work area is clear of trip hazards.

Final assessment of risk

Hazard identified	Severity	Probability	Risk Factor
Chips in eyes	3	1	3
Hair or clothes caught in chuck	3	1	3
Hair or clothes caught in belt drive	2	1	2
Cutting tool breaking	2	1	2
Cuts from sharp objects	1	2	2
Injuries from dropped objects	2	1	2
Objects ejected from chuck	1	2	2

Points system

Hazard severity	Points Rating	Definition
Nil	1	Very minor injury, bruise, graze, no risk of disease.
Slight	2	Minor injury, which would allow the individual to continue work after first aid treatment on site or at a local surgery. The duration of the stoppage or treatment is such that the normal flow of work is not seriously interrupted.
Moderate	3	Temporary disability causing injury or disease capable of keeping an individual off work for three days or more and reportable under RIDDOR
High	4	Causing death, serious injury or permanent disability to an individual.
Very high	5	Causing multiple deaths and widespread destruction eg. fire, building collapse.

Hazard likelihood	Points Rating	Definition
Remote possibility	1	There is really no risk present. Only under freak conditions could there be any possibility of an accident or illness. All reasonable precautions have been taken - This should be the normal state of the workplace.
Unlikely	2	This incident or illness might occur but the probability is low and the risk minimal.
Possible	3	The accident may occur if additional factors precipitate it, but it is unlikely to happen without them.
Highly likely	4	Will happen more often than not. Additional factors could precipitate an incident but it is still likely to happen without this additional factor.
Inevitable	5	If the work continues as it is, there is almost 100% certainty that an accident will happen, for example: A broken stair or broken rung on a ladder Bare, exposed electrical conductors Unstable stacks of heavy boxes

Risk Rating Score	Definition	Action
1 to 4	Low	No action required
5 to 9	Moderate	Reduce risks if reasonably practicable
10 to 15	High Risk	Priority action to be undertaken
16 to 25	Unacceptable	Action must be taken IMMEDIATELY