Tools (9) :
a Chinese mini-lathe

Page created on 07/02/2025.

Preamble

I’d like to make it clear from the outset that I have no illusions about the quality of such a tool, which costs less than €250, whereas a lathe considered to be more or less serious — I’m thinking of the Vevor or Proxxon models — starts at around €800.

My needs and my constraints don’t allow me these options: the most important constraint is the lack of space, which implies light equipment that’s easy to move around. Secondly, I’ll only be turning parts that are less than 50 mm, decorative and non-mechanical, requiring only relative accuracy.

The model chosen is from The First Tool. It is available from a number of sellers on AliExpress, with prices (pay attention to the power of the motor) and delivery times that vary quite a lot, depending on where it comes from — direct from China or a European country. Mine arrived from Germany in five days, even though the country advertised was Spain.

Website photo.

Discovering

What’s inside

Inside the delivery box, the mini-lathe is held in a pre-formed cardboard shell. There’s nothing to assemble. As well as the machine itself, the packaging includes:

Website photo.

1. Plastic base.
2. Standard mains cable, approx. 1 m long, with bipolar plug.
3. Bag containing three Allen keys, two round bars, a centring pin, four crank handles and screws.
4. Pre-cut self-adhesive feet in thick foam.
5. 12 V / 60 W power supply unit with output cable equipped with switch and female power jack ⌀ 5.5 × 2.
6. Centring tool.

Finally, we discover a manual consisting of three A4 sheets, in English.

The design is based on extruded aluminium modules with dovetail grooves, measuring (w × h) 50 × 50 mm: a base, riser blocks, a motor block, a block for the feed and one for the tailstock. There is also, of course, a tool post.

The whole unit weighs 4.4 kg.

Fixing the blocks together

The blocks are fixed one on top of the other using double dovetail wedges with angled faces. The drawback of this system, as we’ll see, is that it doesn't allow the blocks to be clamped really parallel to each other. For this, it would have been necessary to have a parallel external clamping system, similar to the gibs on mobile carriages.

Click on the image for a closer look.

Transmission between the motor (12 V, 60 W) and the chuck shaft is via a toothed belt, protected by a plastic cover.

Spindles

The spindle shaft is hollow, allowing cylindrical bars with a maximum diameter of 6.5 mm to pass through.

There is no drill chuck for the tailstock. The chuck and tailstock center are attached to their respective shafts by M12 × 1 threads.

Click on the image for a closer look at the spindles.

Tool post

Immediately apparent defects

• There is a lot of clearance everywhere:
  • sliders
  • turret
  • cranks
• The cranks are operated by jerks; their hardness varies along the movement and according to the direction of rotation.
• There is no speed variation.
• The motor cable is on the front, which is annoying.

Putting into service

Removing clearance

The first thing to do is tighten all the screws, then adjust the clearance on the carriage slides. There are three: one for the feed, two for the tool post (cross-slide). Why two? Between the two is a graduated ring that allows the tool post to pivot. To adjust this, you have to loosen three pointed screws set at 120°, which are difficult to access. What’s more, their points mark the material and it becomes impossible to correct the default setting, as the screws return to their previous marks. I replaced them with standard M4 flat-head screws.

The slide clearance is also adjusted using point screws on plastic gibs. Here again, the tips of the screws dig into the gibs more and more as they are used, causing the play to reappear and even risking tearing the gibs sooner or later. These screws cannot be replaced by flat-ended screws, as they bear on a surface inclined at 60°: there would be a risk of the gib shifting under the thrust. These gibs, which are too soft, must therefore be replaced.

Replacing the gibs

Ideally, I’d use 3 or even 3.5 mm aluminium sheet, but I only have 2 mm. So I doubled it with 1 mm polystyrene (PS) to act as an anti-friction layer.

I cut 9 mm wide strips of aluminium. I use the carriage body to hold them at a 60° angle so that I can mill their edges. I first place a 1 mm thick, 28 mm wide PS spacer at the bottom of the female dovetail, to raise the future gib a little and avoid the risk of machining the support itself.

Next, the gib is placed and secured with roughly shaped hardboard wedges, which are forced in. Check that the gib rests firmly on the PS spacer at the bottom of the dovetail.

The height of the ⌀ 6 milling cutter is set to remove 1 mm of material. After milling, deburring is carried out on the sharp edge. The gib is then turned over to machine the opposite edge.

To improve the adhesion of the glue, the surface opposite the adjustment screws is scratched with abrasive paper, along with the PS shim, then these two parts are glued together with C.A. glue. This will be enough to prevent them from moving against each other.

The old gib is on the right.

Adjusting the gibs

An initial adjustment is made without the feed screw: this gives a better feel for the friction. After assembling the slides, I tighten the pointed screws quite a bit to mark the gib and prevent it from moving. I then loosen the screws and tighten them again, sliding the moving part to feel the friction. It’s important that the gib returns to the same position after disassembly; to do this, I draw a mark with a felt-tip pen between the body and the gib.

Removing play from the handwheels

The handwheels are mounted on their cylindrical shafts with a simple flat to prevent mutual rotation, and secured with a ‘Nylstop’ nut.

There is a space of 0.2 to 0.3 mm between the flats, giving a very large amount of play. To eliminate this, I make nickel silver shims measuring 15 x 2.5 x 0.2 or 0.3 mm (depending on the case). Each shim is scratched with sandpaper, as is the handwheel flat.

The shim is glued to the flat surface using CA glue. The edges of the shim are rounded with a file.

After reinstalling the feed screw with its washers in its bearing (and lubricating it), the handwheel head is reassembled and forced in.

Before reassembling, the screw is oiled and the slide bearings are greased with petrolatum.

The result is much smoother operation than before.

Chuck

The chuck supplied has three zinc alloy jaws. Outside diameter: 48 mm. Minimum internal tightening: 2.5 mm; maximum tightening: approx. 25 mm.

Tightening the chuck is counter-intuitive, as you have to unscrew it to tighten it. It is locked not with a spanner, but with two pins supplied, one in the knurled part, the other in the jaw support.

Measuring concentricity with a dial gauge reveals an out-of-roundness of 16/100 mm.

Click on the image to see the other dial gauge position.

This out-of-roundness can only be corrected by machining the jaws with a drill in the tailstock, correctly aligned, which is not possible at the moment.

Misalignment

Alignment is checked between the tip of a centring pin and the travelling lathe center of the tailstock.

Click on the image for a closer look at the tips.

This offset exists in both the horizontal and vertical planes.

To compensate for the vertical offset, I placed two pieces of 0.1 mm copper strip under the lathe base block ①. For the horizontal offset, I placed two 0.2 mm pieces of nickel silver spacer between the same block and the vertical reinforcement plate ②..

Click on the image for a closer look at the spacers.

Warning: when I tighten the double dovetail inter-block fixings, the blocks can move and so lose the adjustment so painstakingly achieved. Clearly, this machine is not very well designed…

Other modifications

Cable entry

As already mentioned, the power cable entry is on the front, which is annoying. So I mill an identical cable entry at the rear of the motor block cover plate, mill ⌀ 6, depth 2 mm.

Cable for connection

Purchase of additional parts

Drill chucks

A drill chuck for mounting on the tailstock would be very useful, but is not supplied. It is fitted with an M12 × 1 thread.

Note: Chinese mini-lathes seem to be copies of the Unimat 1 Classic. The proof is in the pudding (but at almost twice the price!):

Photo on The Cool Tool.

Cutting tools

The 4 mm square bar supplied was insufficient, so I bought a set of Proxxon tools. They fit into the tool post with a 0.7 mm shim to obtain the required height.

Grinding the chuck

The concentricity of the chuck is restored using a drill collet on the tailstock side. With the chuck clamped as tight as possible, the first pass was made with a ⌀ 2.5 mm bit, the second at ⌀ 3 mm. Each jaw then had to be reworked for deburring. I finally achieved acceptable, though not perfect, concentricity.

Turning tests

I carried out tests with a round brass bar ⌀ 4 mm, using the Proxxon form 1 tool (cutting edge to the left, for turning). To obtain an acceptable surface finish, you need to rotate at high speed, with passes of no more than 0.1 mm and a slow feed rate. Despite these precautions, the part being machined can sometimes climb onto the tool and get stuck! The result: a damaged part that has to be remade!

Turning over about 12 mm with a 4/100 “finishing” pass, which was supposed to produce a cylinder with a diameter of 2 mm, resulted in a variation of 0.1 mm from one end to the other!

I also tried to drill a centre to use the tailstock, using a carbide ⌀ 1.5 mm drill — I don’t have a centring drill —, but this drill was off centre again, despite the care I had taken with the alignment setting.

Conclusion

After reading the above, you can imagine that I’m not delighted with my purchase.

As I said at the outset, I wasn’t expecting excellent results, but I was disappointed nonetheless! So I won’t recommend this machine under any circumstances, despite its flattering appearance. In fact, its modular design is its main flaw, resulting in a lack of rigidity, and misalignment.

Return and refund

Without really believing it, because I had exceeded the 15-day return period (if I understood correctly), I made a request for a refund, which was accepted within three days (the amount includes the item and shipping costs). A return label was sent to me. Well, the refund was made after two weeks.

Alternative

For a similar footprint and weight, but at twice the price, Proxxon offers the FD 150/E “precision” lathe. I’m not sure that the quality is proportional to the price, but this mini-lathe offers some interesting features, such as quick release of the tailstock via a lever, two mechanical speeds, speed variation, etc. In addition, it accepts tapered shanks, and ER 11 collets.

See the promotional video on Youtube.