Harrison M300 Lathe
 | This tool requires an induction. Induction information can be found at https://somakeit.org.uk/inductions-and-processes/ |
| Type | Machine Tools |
|---|---|
| Manufacturer | Harrison |
| Model | M300 |
The Harrison M300 lathe is a metalworking lathe which we have owned for several years.
It has a fairly rigorous induction, which requires less experienced lathe users to be supervised for a while before they can use the machine unsupervised.
Workholding
Three Jaw Chuck
The 'self centring' three jaw chuck is generally the standard chuck for turning cylindrical parts on the lathe. It holds cylindrical or hexagonal workpieces reasonably concentrically, but if you have to take a part out of it, you will have to use the four-jaw, or centres, to turn it perfectly concentrically.
Four Jaw Chuck
The 'independent' four jaw chuck is a larger chuck than the three jaw, and thus can hold larger workpieces. It requires a dial indicator to centre a part in it, by moving pairs of jaws to hold the part.
It can hold parts perfectly concentric, with some work adjusting it, thus allowing the removal of workpieces.
Centre Turning
Turning between centres involves centre-drilling 60 degree hole in both ends of a part, then putting the workpiece between a revolving or dead centre in the tailstock and a dead centre in the headstock, with one or two carriers to drive the part.
If using a dead centre in the tailstock, the amount of pressure on the part should be carefully controlled, and grease should be used on the centre. Excessive pressure causes friction, and can break the dead centre.
Faceplate
The faceplate is a recent acquisition, on loan from Joseph. It should not be used unless all other options for machining have been exhausted, but involves essentially bolting parts to the faceplate.
Tools and Tool Holding
The lathe is equipped with a Dickson-style Quick Change Tool Post, with several tool holders, which are kept on the wall next to the lathe.
We also have an assortment of brazed-carbide, high speed steel and carbide inserts which are all useful for different materials and cuts.
Carbide Insert Tooling
Tungsten Carbide tooling is extremely hard, which makes it very useful for turning steel, cast iron and other hard materials, along with aluminium. Carbide inserts can be replaced easily in a tool.
As a general rule gold-coloured inserts are usually designed for some sort of steel, while silver-coloured (shiny) ones are designed for aluminium. The aluminium inserts can also be useful for taking light cuts in steel, as standard inserts for steel are not necessarily great for taking light cuts.
Depths of cut of up to 2.5mm can be taken in some steels, while for other types, barely 0.5mm depths of cut can be taken. Experimentation and experience is generally required to determine the optimum depth of cut and feed rate.
High Speed Steel
HSS requires a lower spindle speed, and frequently less aggressive feed rate, than carbide tools. It can be ground relatively easily into shape, but also requires occasional regrinding to keep the tools sharp.
For brass and bronze, HSS is recommended as it is easy to make a zero-rake tool which doesn't 'dig in' to the workpiece, and leaves a good surface finish.
Some of the tooling is made of HSS-E or HSS alloyed with cobalt. These tools are harder than normal high speed steel and last much longer between sharpening, and thus are more useful for turning steel and cast iron.
| Material | Carbide Insert | HSS | Brazed Carbide |
|---|---|---|---|
| Aluminium | Yes, polished inserts | Yes - may need to make a tool | |
| Brass | Not recommended, polished inserts work | Yes | |
| Bronze | Not recommended, polished inserts work | Yes | |
| Mild Steel | Yes | Yes, slower and with coolant | |
| Tool Steel | Yes | Yes, slower and with coolant | |
| Stainless Steel | Yes | Not recommended | |
| Cast Iron | Sort of - may be better with brazed or HSS | Yes, use cobalt blanks to make tool | Yes |
Maintenance and Inspection
Regular Maintenance
- Oil levels should be checked and oil should be added to each oiling point for every day of use.
- All swarf and debris must be cleaned up at the end of each session.
- All coolant must be cleaned off the ways.
- All tooling must be put away in its designated place at the end of each session.
- All lathe tools must be kept sharp - please report if we are low on tooling, or if any non-insert tooling is broken.
- Keep the lathe and tooling clean using blue tissue roll and a brush.
Hack The Space/Superuser inspection
- General lathe clean - Remove any remaining swarf, coolant residue, etc.
- Check tailstock alignment.
- Check oil levels - headstock, gearbox and apron.
- Oil all oil points.
- Check stock of tooling and inserts.
General notes
The lathe takes ISO68 slideway oil in the headstock, apron and all oil points. This is kept near the lathe in a large bottle, along with the small oil cans.
The gearbox requires gear box oil CHECK VISCOSITY IN MANUAL.