Just to give you an idea what to look for in your ideal lathe. This is only for people who want something a little larger than the mini-lathes.
Swing and power. If you want to always make small bits, great. But if you ever need to clean up a brake disc or drum or any other types of large swing jobs that the neighbours or friends bring along (a sure way of getting into good books and earning brownie points), having say a 4.5" swing (height over the bed) or above will come in handy, or a gap bed that will allow you to do such sizes close to the spindle. When you turn these large sizes or heavy cuts, you need power. Normally in the smaller lathe ranges, you should be looking at 3/4HP and above.
Normally bed length doesn't come into it, standard lengths will cope with most of what you do. Only if you want to do long items should you need to go for an extended bed range. The longer the bed, the less rigidity.
Spindle bore size. Get the largest one you can, the bigger the bore size, the more rigid the spindle will be, plus you can get larger jobs up the bore. 3 Morse Taper is really the smallest you should be looking for, below that, it will only have a small bore through the spindle.
A spindle speed change gearbox or variable speed is nice to have, but don't be put off by a belt and pulley system. They are usually quick and easy to change and as you gain experience, you will find you only use two or three of the range under normal conditions. The main downside is if you need to replace the belt. That usually means a complete head stripdown, but that can easily be avoided by fitting linked belts.
Quick change gearboxes for screwcutting. Don't buy a lathe just because it has a screwcutting gearbox. If it has one great, but don't be put off if it doesn't. You will find that you won't be swapping and changing screwcutting setups that often, so as long as it has the full set of gears, you set the machine up for fine feed cuts and only change the gears when you want to carry out single point threading. If you are only ever going to use taps and dies, you will most probably find you only change your feed speeds a couple of times a year, just for doing those special jobs.
A power cross feed is definitely a thing to have if you can get it. It turns a PITA job into a breeze, and the finish on the machining makes it worthwhile.
Fixed DRO's (digital readouts) are now starting to become very popular on the newer more expensive machines. Not the little readouts you get fitted near the handles, but the glass scale ones that have a dedicated display head. You can get setups to fit to larger machines, and there are now read heads that are very small and can be fitted to rather small machinery. Having DRO's takes you into the realms of super accuracy, where you can work easily to 0.0001" or even 0.00001" if you are a masochist.
This is mine that I have fitted
A bit over the top for most people, but I am into precision machining, and this allows it to be done quickly and repeatable.
On the casting side, you should be looking for bulk, big and beefy. The saddle should be the same. The more rigid and heavy the setup, the better the machine will cut.
For the tailstock, a camlock is almost mandatory nowadays, it allows the tailstock to be released or locked in seconds. Also, if you can, get a tailstock that allows for setover. This will allow you to do fairly long tapered parts. 2MT or 3MT is the standard sort of sizes nowadays, and that will allow you to have all sorts of tools to be fitted into it.
If you are going for a benchtop model, make sure you DO fit it to a rigid and flat benchtop. I would recommend at least a piece of kitchen worksurface. Don't under any circumstances use it if it has rubber feet underneath, get it firmly bolted down onto something flat.
I am just doing a repair to a mini lathe that had twisted over time that I suspect was caused by that error. The fault was picked up when I came to do a machining job on the bed.
http://madmodder.net/index.php?topic=627.0That does show that small lathes can easily 'bend'.
I hope that this has helped to make things a little clearer.
John
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Topic: What metal working lathe? (Read 43733 times)