HackSpace magazine

Stationary belt sander – direct from Shenzhen

By Ben Everard. Posted

Machines that stand on your bench and whip loops of sandpaper around are known as bench grinders or stationary belt sanders, depending on what they’re designed to do. They’re used by woodworkers because they’re good for cleaning up cut wood. However, they’re probably most useful for working with metal – they’re heavily used for knife making, and can also be used for tool sharpening. Typically, they take long loops of sandpaper (around one or two metres long) and drive this with a powerful motor. They can aggressively remove large amounts of metal.

However, they’re also expensive tools. You can get this function for a fraction of the cost with a mini bench grinder. Similar models are available from many direct-from-China websites. The model we got was a ‘KKmoon Multifunctional Grinder Mini Electric Belt Sander DIY Polishing Grinding Machine Cutter Edges Sharpener Power Tool’ from the Chinese-Dragon Tool Store on AliExpress. It contained ten sanding belts in a variety of grades, and cost £36, including delivery to the UK.

It takes 25 mm × 330 mm sanding belts (some options also have 15 mm or 30 mm wide belts). Perhaps the first thing to note is the cost of replacement belts. While some deals are available if you look, it’s quite common for ten replacement belts to cost half the price of the bench grinder itself!

The frame of the machine is made of stainless steel and appears sturdy. It feels solid in use; however, there’s little protection for the motor, which means that it could get damaged or short-circuited if you’re not careful. The unit itself takes a 5.1 mm DC barrel jack for power. Our machine came with an additional power supply, though not all do. The provided power supply is adjustable between 12 V and 24 V, and this provides a rudimentary speed control.

Our main test of this machine was grinding a bevel on a stainless steel chef’s knife we’re making. Compared to a full-sized (or even a moderately small) belt grinder, this is quite underpowered. However, with a little patience, it did do the job. Push too hard and you can slow the motor down too much, so it’s a case of light pressure and taking your time. This reviewer finds slowly grinding bevels quite a peaceful experience, so is quite happy to take a little time over it. However, if you’ve got a stack of things to shape, then you might find it more annoying.

There’s a small plate that you can grind against, and an adjustable rest for holding your workpiece. However, the adjustable rest can only hold about 10 degrees either side of 90 degrees, which may be useful for putting a nice sharp corner on wood, but it’s useless for bevelling a knife. We ground our bevel free-hand, but if you were to use this grinder a lot, you may wish to build your own jig to hold your workpieces.

The grinder comes with rubber feet, but it’s not really usable when just placed on a bench – it jumps around too much. We found that we had to clamp it down, but the clamps made it a little difficult to work around. A far better, and more permanent, solution would be to use the holes that the rubber feet screw into to bolt it down to either your workbench or a larger surface that you can then clamp down with ease. This would also give you space to attach a jig for holding workpieces at precise angles for bevel grinding and sharpening. This isn’t comparable to a regular bench grinder. It’s much smaller and much less powerful. That said, neither of those factors are necessarily a problem – it depends on how you want to use your machine. For sharpening tools, adding too much power can result in removing too much material and the steel becoming overheated (leading to it losing hardness). A machine such as this could – with the addition of a jig to help hold tools in position – make for a good sharpening setup. However, if you want to use it for heavy-duty grinding, or quickly shaping metal, you’ll probably be disappointed. Similarly, if you want to square-off pieces of wood, you might prefer a sander with a wider belt.

Our workshop sees only occasional metalwork, and as such, a little belt grinder like this serves a purpose that we couldn’t easily fill otherwise.


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