DIGITEN 4 Digital LED Tachometer RPM Speed Meter+Hall Proximity Switch Sensor NPN Blue

Worked great after I moved the sensor far enough from the magnet, like the directions say.

I wanted a direct readout of spindle speed on my metal lathe, and this little gauge/sensor fit the bill perfectly. It uses a magnetic sensor to detect a magnet attached to the shaft spinning past it. You need to tape, glue or otherwise affix the small disc magnet to the shaft you're monitoring, so make sure you attach it securely if your machine will be spinning at high RPMs. (It claims to measure speeds up to 9,999 rpm; I'd be a little nervous about the magnet flying off under those conditions. I don't know if you could use a stainless steel (non-magnetic) strap to attach it and still have the sensor "see" the magnet, but it wasn't a concern for my usage. Just a heads-up to others who might need to use it in a higher-rpm range. (Probably better to use a reflective vs magnetic sensor for high shaft speeds...)

The original tach on my PM1127VF lathe died. I was skeptical about this one responding well at low RPM because it only has one pulse per revolution - but in fact it works really well and is very accurate (I checked it at several speeds with a hand-held tach.) Installation was very straight forward. Such a deal!

Bought to monitor the speed of my old Myford lathe. Easy to wire up but ideally needs to be built into a box to protect the electronics and connections.You also need an external low voltage main’s adapter to power it, and it’ll work with any 8-15v DC supply ( I used a spare 12v one )The transmitter unit has a decent amount of thread on it to adjust the distance to the magnet which is fixed to the moving part.

The device is easy to install and it came with instructions. You will need a suitable 12v power supply (I used an old network router's power supply) to provide 12v power to the device. I mounted the display in an aluminium enclosure to make it look neater and to protect the electronics.The device works well, however, it is a little slow to update its display especially when stopping the machine.Well worth fitting to a milling machine/lathe/pillar drill or similar.