The following should be read in conjunction with Andrew Carruthers interesting article on a mill rpm display in MEW 288. Whilst setting me thinking and strong on aesthetics it was lacking in information on the display unit’s type, model number or cost. The wiring diagram only referred to the unit he had (though it would appear to be common to many) and the DC negative is not earth. Since the power supply is 240v mains this incorrect terminology could be dangerous. If a spare power supply is to be reused, check that it is DC and not AC although it is a simple task to rectify the ac with a bridge rectifier and smoothing capacitor. Also check on the polarity of any fitted plug, the centre is not always POS +.
Putting “hall effect tacho” into a search engine will result in numerous suppliers online. The pictures in this and Mr Carruthers articles will identify the right unit and prices seem to vary from £7 upwards. The one I purchased came with all that was needed, including the mounting bracket for the sensor and a magnet for £11. The unit needs a power supply of between 8v and 24v DC, about £6, if needed. Setting up the supplied sensor and magnet is easy. On the rear of the sensor is an LED, photo 1, that glows when powered up and increases in intensity when the magnet triggers the hall effect device. Fitting the magnet to the shaft, pulley or whatever and rotating it will show if the magnet is the right way round and aligned before it is permanently mounted. I had carelessly forgotten that the small and very powerful magnets used are very brittle and will shatter if allowed to smack onto steel. No prizes for guessing how my memory was refreshed!
هذه القصة مأخوذة من طبعة February 2020 من Model Engineers' Workshop.
ابدأ النسخة التجريبية المجانية من Magzter GOLD لمدة 7 أيام للوصول إلى آلاف القصص المتميزة المنسقة وأكثر من 9,000 مجلة وصحيفة.
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هذه القصة مأخوذة من طبعة February 2020 من Model Engineers' Workshop.
ابدأ النسخة التجريبية المجانية من Magzter GOLD لمدة 7 أيام للوصول إلى آلاف القصص المتميزة المنسقة وأكثر من 9,000 مجلة وصحيفة.
بالفعل مشترك? تسجيل الدخول
Readers' Workshops - Patrick Cubbon
Patrick Cubbon describes his workshops – a portable one from 1963 and the current accommodation
Desktop Gear Hobbing
Toby Kinsey has designed this fascinating piece of gearmaking equipment
The John Stevenson Trophy 2020
Many readers and forum members will remember John Stevenson, a contributor to MEW but best known for his larger-than life presence on the Model Engineer forum.
From the Archives: Twist drill Sharpening by the Four Facet Method
Giles Parkes, MEW Issue 64, February/March 2000
Dividing on the Warco 220 Lathe
Peter Shaw describes a mandrel dividing attachment for this popular lathe that can be adapted to fit many other benchtop machines
Choosing Steels
Stub Mandrel offers some advice on choosing the right steel for the job
A Storage Story
Robin King shares the lessons learned from his experience of workshop moves
A Simple Drill Grinding Aid
A newcomer to our hobby was having trouble sharpening drills, so Howard Lewis made a simple aid for him
Yet Another Bodge-Up!
Peter Shaw finds a use for some aged homebrew slot drills.
Workshop Press Tooling Part 2
Will Doggett makes a set of tooling for his press tool described starting in issue 285