El) m Drivers &Mechanics
Page 19
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Spherical Turning.
The sender of the following communication has been awarded the 10s. prize this week.
(1602] "J.M.A.Y." (Walthamstow) writes :β " There are many capable machinists engaged in the ordinary routine work as found in the manufacturer's workshop, and who would probably be able to tackle almost any ordinary turning operation that they are likely to meet, but who, nevertheless, would find some difficulty in forming a ball with the usual workshop appliances, i.e., in the absence of a special forming tool.
"This same operation must naturally present even greater difficulties to a man whose facilities are limited to the meagre supply, of apparatus usually found in the small garage. I am, therefore, of opinion that the following simple but decidedly effective method of spherical turning -will be of interest to other readers of D. and M.' pages. " The sketch [which we have had redrawn.βEn.] shows a lathe toolrest. For the ordinary tightening bolts, are substituted special studs, as shown inset, these to be made sufficiently long to allow the top part of the rest to be revolved and yet at the same time to obviate any looseness. If the lathe saddle and traverse; slide be placed so that their centres come exactly underneath the centre of the proposed ball, it will be possible, by revolving the top portion of .the rest instead a sliding it, to form a perfect sphere.
"After having centred the slides, great care must be taken not to move these until the operation is completed. The diameter of the ball must be determined by tapping the lathe tool towards the cent."
To Remove Valve Plugs.
[1603] " E.M." (Ayr) writes :β" Your answer to query No. 2520 of 14th January has prompted me to send the following hints, which may he suitable for your 'D. and M.' page. "When removing valve plugs of the plain type held down by, a gland, I. find that by slacking the nuts holding the ,gland and starting the engine the plug will be loosened by the explosion, and then can easily be removed by .hand. If when using. this method the inlet happens to loosen first, which frequ ntly occurs, take Wont and clean it thoroughly, the eplace and fasten it, leaving only the exhaust plug f ee to move. The same process then repeated will loosen this one also.
" If this plan fails, the bolt screwed to the .same thread as the sparking plug and used, in cOnjunction withtwo packings and plate, as illustrated in the sketch [which we have had redrawn.--En.], makes .a
very good persuader. .
" For screwed valve plugs nothing is better than a well-fitting spanner long enough to -give plenty of leverage, and if the spanner be hammered lightly the most refractory of valve plugs-can be loosened. "I had atone time a very useful plug spanner, made by myself, at a time when I was employed repairing Comrnercars. I got an old brake operating pin from an M.C. chassis and sawed the spindle off flush with the back of the cam ; the projecting pins on the cam face I filed to fit the plugs for R.C. type and heavier cars. The other side of the disc I drilled and tapped to receive two steel pins pitched GO as to suit the plugs from Y.O. type downwards.
" It has the advantage of being small, light and strong, can be easily carried in the tool bag, and almost anything can be used as a lever for it."