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VALVE-GRINDING TOOLS.

18th December 1923
Page 29
Page 29, 18th December 1923 — VALVE-GRINDING TOOLS.
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Some Useful Accessories Made by Our Driver and Mechanic Readers.

FOR AN ENGINE to give of its best, the valves must bed well on to their seats. It follows, therefore, that. the driver who would keep his wagon at its highest pitch of efficiency must be capable of keeping his engine valves and their seatings in good trap:. For that purpose it is often convenient to have some special tools as an aid to valve grinding. Of the several letters which we have before us, dealing with this matter, we are inclined to give one from "11..11_13." of Rotherham first place, and to him we award the 15s. prize. Actu--: ally, it describes a tool which does not become necessary until the valves and their seat have arrived at a state when merely grinding the one into the other -does not affect the radical improvement which is expected.

The correct angle between the faces of a valve or valve seating and the horizontal is, in the majority of cases, 45 degrees. The width of the seating_should not exceed an eighth of an inch; it may be less, but it must not be more. When, as the result of persistent grinding, this width is exceeded, or when as the result of neglect, or from other cause, theseatink,ra are so badly burnt and pitted that grinding does not effect a cure, then the valves have to be trued up either in a lathe or in some special tool which can be bought for the purpose.

The Beatings, too, must be recut, and for this purpose also there are suitable tools on the market. " H.A.13.," however, has made .a simple, inexpensive and efficient one of his own; it is illustrated by one of the accompanying sketches, and may be simply described as follows t--A• spare valve cap is to be procured from the maker. It must be bored truly in the centre, the diameter of the hole being the same as that in the valve guide. A piece of cast-steel bar, somewhat larger in diameter than the valve spindle and 6 ins, long or there. abouts according to the dimensions of the cylinder, is turned down to the same diameter as the valve spindle except at. one point, as indicated on the sketch, where a narrow collar is left, which is subsequently dressed off, leaving only two projecting tongues, as shown. These are for the purpose of driving the cutter, which fits on to this spindle, having slots

cut in its upper surface with which these tongues engage. At the top end, the spindle is squared, as shown, to accommodate a spanner or tap wrench. The cutter is also made from cast-steel.,

Its outside diameter is in. more than that of the head of the valve; its depth is such that, when it rests upon the seat the valve cap cannot be screwed right down into place by about in., owing to the fact that its underside is in contact with the top of the cutter-The edges on this tool are simply serrations, 60 in number, and cut wills a 6-in. smooth half-round file. When ready it must be placed in the fire, heated to blood-red, and then plunged into whale oil.

When about to use the tool, begin by resting the cutter on the valve seat which is to be ground. Drop the spindle into place, so that the tongues engage the groove, and finally slip the valve cap over the spindle and screw it down until it makes contact with the top of the cutter. Turn the latter by means of the squared head of the spindle, screwing the valve cap down, as need arises, to apply the feed.

Another valve seat tool, more simple

in form, is described by. " V.R." of Wigan. He makes it from an old valve and a piece of smooth flat file. The bead is cut from the valve, so as to leave the spindle as long as possible. A piece of flat file is then ground into shape, as shown in the sketch, the cutting edges being set at the right angle to ensure their making a proper valve seat. The cotter hole in the spindle must be enlarged and squared up to accommodate the tool and a small steel wedge, which, as shown in the sketch, is used to hold it in place. A squaremust be forined On the top of the spindle; and the tool is then complete. The method of its operation will be obvious. Some engine_ valves, we are reminded by !` C.C.W." of Nottingham, have a couple of small' holes drilled in their top surfaces to facilitate grinding. This arrangement is not, on the whole, so convenient as the more general practice of cutting a slot, to accommodate a, screwdriver; for one thing, it has the disadvantage that, as no two makers agree as to the right distance from centre to

centre of the two holes, a tool which will •fit one is of no use in connection with another, and although this does not matter in a case where only one type of machine is used, in a garage where all kinds of vehicles are brought in for attention, it is sometimes a bit of a nuisance.

The tool which " C.C.W." describes is designed to get over this difficulty. It needs but little description, the way in which it is made being obvious from the sketch. To use it, is necessary, first of all, to take the dimensions of the valve as regards the distance apart of the two holes. The nut (131 is then slackened, releasing the plate (C) which holds the screws (E) firmly in any position, in which they may he put 'These screws may then be moved in their slots until they are the same distance apart as the holes in question, care being taken to locate theta at equal distances from the centre. They are then tightened in place, and the nut (B) screwed down upon the top of the disc, when the tool is ready for immediate use again.

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Locations: Nottingham

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