Long a favourite amongst model engineers - and based on the Deckel SO and SOE machines - the Quorn was designed by Professor D. H. Chaddock and available only as a kit of parts for completion at home. Today, with even well-used Deckels and Chinese-built replicas still commanding high prices, the Quorn remains an attractive proposition - though a challenging exercise to complete, even for the skilled.
Originally devised to sharpen the milling cutters necessary when building the Dore Westbury milling machine (of which Prof. Chaddock was an owner) the grinder can (without modification) also tackle lathe, shaper and planer tools, taps, reamers and twist and centre drills. With some adaptations it can also be used to modify or create special cutters - for example, those necessary when thread milling and cam forming in hard materials. Although at first sight a complex piece of apparatus it is, essentially, very simple to use and even a beginner can produce first-class results after only perfunctory practice. The secret of its success is the ability to mount a range of different wheels - while being able to present the work to them in an almost unlimited number of ways. The cutter, once mounted in a suitable collet, or held in a clamp, can be slid lengthwise under the control of a micrometer-equipped screw whilst also being rotated (oscillated or indexed) tilted and rocked in multiple planes. Degree engravings, protractor scales, setting pins, micrometer and limit stops are fitted where required and added greatly to the simplicity and ease of use.
Not only is the Quorn an amazingly useful tool, but building it an absorbing pastime, allowing the creator to produce either a utilitarian working example or one finished to the very highest cosmetic standards.
Two versions of the Quorn were made, the Mk. 1 and Mk. 2. The Mk. 2 did not supersede the Mk. 1, but incorporated a number of small improvements including the ability to fit belt and wheel guards. In 1986 Prof. Chaddock modified the design of the rotating base to eliminate the steel casting, and replaced it with a fabricated component. The revised kits contained all the necessary parts, as before, together with the materials necessary to construct the new base and two additional steel blanks, one for the backplate and another for the division dial. The Mk. 1 was issued with three sheets of drawings, the Mk. 2 had four. The Quorn uses nine springs in its construction: one anti-backlash; one thimble; one index and six bearing pre-load - these originally being offered as one set, finished and ready to use.
Should you find a used Quorn without a motor (or one that is not working) it's vital to use the correct type as recommended by the designer: 1/6th h.p. running at 2,800 r.p.m. The more commonly available 1/4 h.p. 1450 r.p.m. can be used, but will need a larger pullet to get the grinding wheel speed right. Do check with the grinding wheel maker what the correct speed is and, if in doubt, scrap those provided and buy new ones (there is also the danger that, unknown to you, the wheels might have been dropped or otherwise damaged and could burst in use). Some of the units shown below have no wheel guard; if yours is the same, the writer would strongly advise making one. The best drive belt to use is a genuine Swiss-made Polycord in the right grade of material - these can be found here
A number of home-built grinders inspired by the Quorn have been built, including the very fine example shown here - if you can't afford the Quorn kit--why not build your own.
A Manual is available for the Quorn Tool & Cutter Grinder..