The machine that will most likely be bought first in a new engineering workshop is a lathe. A mill or pillar drill are of course very important but a lathe is usually the central feature, around which all other work is done.
That alone makes it imperative to get the right lathe. Then of course there is the small matter of how much the lathe will cost, with prices of Axminster products ranging from £500 right up to £15,000. Making sure you get the right lathe first time becomes even more important.
With this in mind, we’re here to help you out a bit. Here we will look at the main considerations and key features of an engineer’s lathe, so you can make the best choice.
Why do you need a lathe?
The simple fact is it’s the most versatile machine that you can have. Not only can you turn, bore, grind, face and part off but with some slight modifications, you can also carry out milling jobs. Now of course doing milling jobs on the lathe won’t be as accurate as a mill but, you can still do them. With one in your workshop, you will be able to perform a wide variety of tasks at very good standards. It’s a no brainer…
Before you start looking at the lathe you will need, it’s best to draw out a list of your own needs. This is so you can narrow down the wide selection of lathes that are available on the market.
- Workshop space – As with all machinery purchases, this is key. If you have a space in the workshop available, try to choose as large a machine as possible. Always remember though, bigger machines, require better foundations.
- Size of the job – This will also ultimately affect the size of the machine you would like to buy. It’s always best to get a machine that’s capacities are above the maximum work size.
- Ease of use – Larger lathes will usually be geared rather than variable speed, but some are both, so choose wisely. If you are just getting into engineering, it’s best to go for a variable speed machine as the ease of use is second to none.
- Types of job – Very important as certain jobs will require different machine speeds. A general rule of thumb is that larger machines will not run as fast as smaller ones.
- Budget – What sort of money are you putting aside for the lathe? You must also consider tooling and any extra accessories that will improve the performance of your machine.
Now that you understand your needs and requirements, it’s time to look at the key features that every good lathe should have.
Steel and cast iron construction is imperative in an engineering lathe. This will give the machine weight and stability as well as the ability to absorb any vibration from the motor or the force of the cut.
Design of the bed
There are two main bed designs that you will find when looking for a lathe; the flat bad, or the V bed. As a company, we certainly prefer the V bed design as you will see on many of our machines. This is because they are far stronger and rigid, as well as allowing the headstock, carriage and tailstock to be completely parallel with each other.
The power of the motor is often the key feature in many machines, but if you have a size of machine in mind, the power will most likely match this. What you really need to think about is torque. With even more emphasis on the torque under load and at low speeds. A lot of brushed DC motors will stall at low speeds when the load is high, and with many jobs being needed at low speeds (such as screw & thread cutting), you need to buy a lathe, with a high torque motor. Other benefits of these type motors is they are variable speed, run at almost 100% efficiency and are very quiet. For more information on this, read this piece.
The main capacities to look for in a lathe are;
- Centre height – This is the distance from the centre of the chuck to the lathe bed. This determines the radius of the task that you can do.
- Swing diameter over the carriage – This is the maximum diameter that can be turned over the carriage, i.e. a bar, spindle or tube.
- Distance between centres – The maximum length of material the lathe can accommodate. This will be a secondary one due to the fact that most engineers only use the first six inches of length.
These are the features that not every lathe must have but are great additions.
- Threading and screw cutting – Tasks that you will no doubt want to do once you become more proficient. Having these capabilities will make the process much easier.
- Power feeds – This will enable you to do many tasks quicker, and get a better finish, due to the constant mechanical feed speed.
- Morse Taper tailstock and spindle – To enable complete accuracy it’s best to have a morse taper spindle. Look mainly for machines with MT2 or MT3 as these will be the most common for tooling.
Tooling and accessories
As stated in the last section of desirable features, it’s good to check that the lathe you’re interested in has a wide variety of tooling available. So Morse Taper spindle sizes MT2 or MT3 are common, but also check it’s workholding compatibility.
That is where we will look to start. Most new lathes will come with a chuck, with 3 jaw self centring being very common in smaller lathes. Although 3 jaw chucks are very accurate, you can increase this by getting yourself a 4 jaw independant chuck. A quick change tool system is also a vital accessory, this will make your whole machining process much more efficient.
Onto the tooling itself. The three main tasks you will do on a lathe are, turning, boring and facing. So getting these tools from the off will mean that most tasks can be done straight away. Instead of buying them individually, they can be bought in a set. As a start, this should see you through until you are confident enough to tackle more complex tasks.
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Once you’ve sorted the tooling and workholding, we can look at optional accessories that will take your lathe further. A digital readout (DRO) is something more and more people are turning to. Completely eliminating the effect backlash and ensuring complete accuracy. These are expensive though, so consider where your machining wants to go before taking the plunge. A milling attachment will complete your lathes versatility and if you don’t have the space for a mill alone, can provide a perfectly good alternative. Finally, a coolant system will prolong tool life, as well as giving a better final finish.
The lathe is the key machine in the engineer’s workshop, and buying yourself a high quality one will ensure accurate, consistent work for years to come. To get that lathe though, you will need to do your research. We hope that this guide has helped you some way to making the right choice for you and your work.