About mini-lathes

There are a range of small hobby metal-working mini-lathes, made by various factories in China, including Sieg and Real Bull, apparently to a very similar pattern. They’re cast iron machines with approximately 300mm (a foot or so) between centres, though they come, stateside at least, in a slightly shorter and slightly longer version, too. They’re mostly driven by electronically controlled DC electric motors, usually via a two-speed gearbox and toothed-belt drive. They have a gear driven lead screw which can be used for power feed or for thread cutting and they weigh around 40 kilos (88lb). The have a throw of approx 180mm (7″) above the bed.

As lathes go, then, the mini-lathe is small enough to pick up and move around (if you don’t mind lifting 40Kg), but solid enough to take reasonably seriously. The headstock casting sits on the bedway and is bolted down (rather than being cast in a unit with it), most versions these days have hardened bedways, but it’s not really clear to me if this is now standard ex-factory, or a vendor specific option. It has various shortcomings because of being small and built down to a price, but also some very nice features – for example, the spindle speed is continuously variable via an electronic speed control, in both forward and reverse, and the leadscrew drive can be set to disengaged or reversed via a lever on the back. The chuck is bolted to a flange rather than threaded onto the spindle, so the lathe can be worked backwards if desired. Pretty much everything can be replaced or upgraded as required, all bolts are standard sizes and the headstock and tailstock have regular Morse tapers (MT3 and MT2 resp.)

In the USA, they’re known by their nominal size: 7×10, 7×12 or 7×14. That is, (nominally) 10, 12 or 14 inches between centres, although the 7×10 version is, as has been widely observed, more like 8″.

Versions available in UK

As best I can tell, the 7×12 size is the most widely available in the UK, sold by (at least) Machine Mart, Tool Hut, Toolbox, Warco, Chester Machine Tools, Rapid, Sealey and Axminster. Also, Amadeal Ltd. and SPG Tools offer a 7×14 (350mm) version. The lathes come with different names and in assorted colours. As I write (Nov 2011) the prices are £538.80 from Machine Mart, £527.94 from Tool Hut, £499.00 (or £461.50 for the C2A version) from Axminster, £444.26 from Warco, £427 from Chester, £390.00 from Amadeal, £365.00 from SPG Tools and a whopping £691.50 from Toolbox, £614.96 from Rapid and (ulp) £1019.94 from Sealey (all prices include 20% VAT but generally don’t include delivery.)  Don’t take any of these prices as gospel, they’re likely to vary wildly, as all of these resellers have substantial offers and discounts from time to time – basically, you can expect to pick one of these things up new for around £500 or less, as of late 2011.

The more expensive versions from Sealey, Rapid and Toolbox are painted red and badged “Sealey”. The specs say this has a 300W motor. It looks very similar to the Clarke one, with 300mm (12″) between centres and a 80mm (3″) 3-jaw chuck.

Tool Hut and Machine Mart sell a yellow Clarke branded version, which appears to be a Sieg, and claims a 300W motor. It has 300mm (12″) between centres and is supplied with an 80mm (3″) 3-jaw chuck. Clarke supply the lathe with an imperial leadscrew, a metric leadscrew is a modestly priced optional extra (around £25).

Axminster offer two versions in pale grey, described as the Sieg SC2 and Sieg C2A. The SC2 is a newer version, with a digital RPM readout as standard and a 500W brushless motor (but no 2-speed gearbox), along with a few other updates. It has 300mm (12″) between centres and an 80mm (3″) 3-jaw chuck. The C2A is slightly cheaper, looks very much like the Clarke one, has the same dimensions and claims a 250W motor.

Warco‘s is green and has an an adjuster in the righthand pillow block for leadscrew end-float. Warco’s claims a 400W motor, and is again 300mm (12″) between centres and supplied with an 80mm (3″) 3-jaw chuck. Warco offer a choice of imperial or metric leadscrew.

Chester‘s, called “Conquest”, is grey/white/silver, and also appears to have the end-float adjustment. It has 300mm (12″) between centres, an 80mm (3″) 3-jaw chuck, a 400W motor and comes with your choice of metric or imperial leadscrew.

SPG Tools show a couple of 350mm (14″) versions with the larger 100mm (4″) chuck, one of which looks very much like the Clarke one (except it’s blue, and longer) and the other has basically the same spec but looks slightly different. Both SPG’s claim a 550W motor.

Amadeal’s is a Real Bull CJ18 7×14 version. It has 350mm (14″) between centres and the larger 100mm (4″) 3-jaw chuck. This one claims a 550W motor, and also has an end-float adjuster for the (metric) leadscrew.

All apart from the Axminster SC2 version have two speed gears as well as a continuously variable electronic speed control, the bigger brushless motor in the SC2 is reckoned to handle lower speeds with higher torque, eliminating the need for a gearbox.

Amadeal also offer a wide range of spares, including a 14″ bed conversion kit for shorter Real Bull lathes, and the spindles with integral 4″ chuck plates. I wouldn’t like to say which, if any, of the Real Bull parts would fit Sieg lathes or vice-versa, but they certainly look very similar. I’m not sure what accessories or how many change gears are supplied with each version – mine (Clarke) came with a total of ten, there are six in the photo on Axminster’s site, though. A replacement set isn’t too expensive. Change gears, at least, seem very likely to be interchangeable between Sieg and Real Bull – I read somewhere that some machines have broader 4mm keys on the spindles, but the keys could be swapped or modified (or keyways in the gears altered, or additional keyways cut) and the spindle sizes and gear pitches are the same as far as I know.

Disclaimer

I have no affiliation with any of these companies, nor do I assert that this is an exhaustive list, they’re just the suppliers I could find with a bit of web searching. I’m not sure if there are any subtle differences besides those noted, which might make one or the other worth paying more or less money for – it may perhaps be that the more expensive ones are built and calibrated with more care by their respective resellers, I have no way of knowing. I certainly wouldn’t assume that they’re all the same, or finished to the same standard, just because they look similar. The Clarke one I have seems reasonably tight and well-aligned, but that might be because of its former owner, most people make adjustments to these as soon as they get them home.

The photos are scaled-down screenshots from the respective suppliers’ web sites, used without permission – they may not be representative of their current offerings, and I don’t claim to represent these suppliers in any way. If there’s a problem with using any of the pictures, I’ll willingly and immediately remove them on request.

General

All are basically metric machines, with metric screws for the slides, and general dimensions and fitments being metric, but they tend to be supplied (the Clarke one at least) with a 16tpi imperial leadscrew for thread cutting (the same leadscrew is used for basic power feed). A metric leadscrew kit to replace the imperial one is a reasonably cheap optional extra (around £25). They’re normally supplied with 80mm (3″) 3-jaw chuck and a plain dead centre for the tailstock. Other spares and options, like steady posts and digital read-outs for the slides, a four-jaw chuck and so on are variously priced, and whichever lathe you have, you’ll probably do well to shop around the different suppliers for these. People are using 4″ and 5″ chucks on these lathes, too, mostly with adapter plates, though a spindle with a 4″ flange is available from the manufacturer. Adapter plates can be bought ready-made for the 4″ chucks, though many prefer to make their own.

Change gears and many of the drive gears in these lathes are nylon or similar plastic. Nylon gears don’t generally need lubricating, to the best of my knowledge, and I’ve read somewhere that you shouldn’t use regular mineral-based grease or oil on plastic gears as it tends to weaken them. I don’t know if this is actually true, it’s just something I read. I believe that nylon absorbs mineral oil and swells, which is why you don’t use mineral oil in nylon-lined bowden cables, and I know stuff tends to stick to grease and that grease mixed with filings and swarf makes excellent grinding paste for soft materials, so my personal prefefrence is to keep the nylon change gears non-greasy. Thelittlemachineshop  have a mini-lathe user guide, however, which recommends grease for the change gears. My gut feeling is that grease isn’t actually going to hurt, as long as it’s clean, and it may make the gear-train quieter and smoother, but that light mineral based oils (and especially stuff like WD40) should be kept away from plastic gears.

One U.S. company, thehobbymachinestore, will supply a complete set of change gears, or indeed a complete set of all gears made from steel, at what seem to me very reasonable prices. Ultimately, I’m inclined to swap all but one of the drive gears to steel, I’m ambivalent about the change gears – the plastic ones seem to work well enough and need no grease (at least I don’t think so – thehobbymachinestore recommends greasing them). The reason I would prefer at least one nylon gear in the main drive? Basically, because I’d rather strip a gear than bend something more substantial, in the event of a bad crash or overload. Also, nylon gears run quieter.

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13 Responses to About mini-lathes

  1. Septic says:

    As someone with over 25 years experience in machine tool maintenance, I can say with some confidence that, providing they are made from the correct material, synthetic gears as used on most “lightweight” machine tools are actually more reliable quieter and more importantly, they can increase the lifespan of associated driven components over steel ones due to their natural shock loading reduction.

    Providing that the lathe correctly set-up before use and is not regularly over stressed by using it for jobs that should really be done on more robust industrial machinery, there is no reason to suggest that replacing plastic gears in favour of metal ones is anything but counter-productive and a waste of money. Not to mention the time saved due to the slower wear rate and associated re-adjustment requirements, lower noise levels and reduced vibration.

    Furthermore, there are are readily available synthetic lubricants especially formulated for use with plastic gearing in small volume tubes at nearly every model shop and in my experience it is a good idea to use a very small amount, replacing it regularly during your scheduled cleaning and maintenance routine (which of course we all stick to rigorously 😉

    • lathenovice says:

      That’s a really useful perspective, thanks – I knew the nylon gears were quieter, obviously, but I didn’t know they were slower-wearing – I was thinking of getting some steel ones, but now I reckon I’ll save the money, the nylon ones are doing just fine. The main spindle drive of this little lathe is in fact via nylon idlers, presumably to reduce wear in the brass gears they mesh with? Shock absorbing for the spindle drive would seem to be taken care of by the toothed belt from the motor, which, ah, seems to work well enough when running the wrong way into a blind hole, ahem. I have some silicone lubricant for the gears, which is a lot less sticky and swarf-attracting than mineral grease. And yeah, obviously there’s a scheduled cleaning and maintenance routine, I’m just not going to admit to any details of the schedule, as such 🙂

  2. Robert Tidd says:

    Has anyone had a problem with the circuit board of the Axminster Sieg SC2 Mini lathe with brushless motor. I only had mine for about 1.5 years and it packed in . I have had an electronics engineer have a look and in his view there is a fundamental design fault and incapable of repair. Axminster do have replacement boards , but if I buy one I am not confident that the problem wont manifest itself in the near future

  3. Rick says:

    Ive heard the the PCBs on all these machines dont like moisture in the air and that this is a common fault on all makes

    • lathenovice says:

      It may be, but to be fair, I doubt the rest of the lathe much likes moisture in the air, either… nor do I, come to that 🙂

      Considering that quite a few of the bits of my one were pulled from a bucket that had been quietly collecting water for a couple of years, I reckon the reasonably robust mechanical parts probably make up for any deficiencies in the electronic speed control, for the price at any rate.

      Not that mine’s given any trouble at all, despite a few fuse-blowing abrupt stops etc.

      If the electronics go wrong, I figure I could replace the speed control with a homebrew unit, or perhaps replace the motor and speed control with items designed for large radio-control models, which can be extremely powerful, have nice fine control and are built to take a hammering.

  4. jose says:

    Interesado en torno para metales sc2. Precio y carasteristicas del sc2

  5. jose says:

    Interesado torno para metales sc2. Carasteristicas y precio en euros. España

  6. Geof Woollvin says:

    I bought the parting tool and holder but it brings the parting blade half way down and cannot find centre. Am i doing something wrong ir is it a design fault,. if its a fault how does anybody else part off a job,

    • lathenovice says:

      I’m not sure what you mean – I haven’t bought a parting tool holder, I have a parting tool ground on the end of a bit of 1/4″ square HSS bar, however, with most tools you generally need to at least adjust them with shims and so on to get them at the right height in the toolpost clamp. It sounds like you might have bought a holder that’s simply the wrong shape/size for the toolpost – if you’re sure you’re not missing something (like the parting tool being able to be set at an angle so that its cutting edge height can be varied by sliding it in or out, for example) then you’ll need to modify it, or make an adapted toolpost for it and tools like it, or get a different one, or make some kind of auxiliary clamp to hold it, etc. – without seeing it I can’t really make any more specific suggestions.

  7. Peter Wilson says:

    I bought a c2 lathe several years ago .. the controller died, and I never got round to repairing/replacing it ( I think the failure was due to a loose power connection coming apart.) I still have most of the pieces, but not the board itself, which I am now prepared to build, having since got into electronics. So, I am wondering if there is a specification available for a suitable controller board.

    • lathenovice says:

      Hi Peter, I’d have thought a generic MOSFET PWM motor speed controller would be all that’s needed – if you like I can try to probe mine with a meter or ‘scope and figure out what voltage it runs at, etc. There are spares available but they’re costly: http://littlemachineshop.com/products/product_category.php?category=5&First=M&Last=N

      Someone’s written a troubleshooting guide: http://www.littlemachineshop.com/reference/DriveTroubleshooting.pdf

      • Peter Wilson says:

        Thank you. I do know those sites.
        I’m getting lazy: I just discovered 20 pages of Lathe controller specs, design notes and calculations I made several years ago, but never pursued. I was disturbed by the brushed/mains supply approach, and the fact that my readings in power electronics, suggested that simple (non-professional) circuits seemed to need extra sub-circuits to compensate for what simple circuits didn’t quite handle. Now I’m inclined to follow the brushless route: https://letsbuildone.wordpress.com/mini-lathe-motor-upgrade, and I feel more confident in my ability to create a polished product. I hadn’t realized brushless could be done so neatly, compactly.

      • lathenovice says:

        Yep, i think if mine blew I’d go brushless – I’d probably cheat and just use a pre-built heavy duty brushless speed controller (ESC) from Hobbyking with a suitably chunky motor and provide the control pulses for the ESC with a repurposed servo tester… cheap ‘n’ lazy 🙂 Of course, using an ESC designed for r/c models will result in a lathe that plays a little tune when you switch it on, but I could live with that 🙂 (They use the motor as a sounder to let you know they’re armed and ready, as a safety thing – fingers don’t get along with moving propellers.)

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