Reducing the Cost of Cylinder Grinding.
Page 59
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IT will be appreciated that a machine which facilitates the operation of cylinder grinding, by reducing its cost and the loss of working time which it involves, should meet with a hearty welcome from all classes of commercial motor users.
We recently witnessed a demonstration of an appliance which may be said to embody these advantages. The tool to which we refer is the Hutto cylinder-hone, which is marketed in this country by Harvey Frost and Co. (1924), Ltd., 148-150, Gt. Portland Street, London, W.1.
A four-cylindered monobloe engine was used for the purposes of the demonstration, only two bores being selected for honing. These were Nos. 2 and 3, the latter having been previously scored deeply with a file in order to represent a bad gudgeon-pin score. After the cylinder block had been set up on a surface plate, the two bores were carefully measured, and it was found that No. 2 was .002 in. and No. 3 .003 in. larger in diameter in one 'position than at another position separated from it by 90 degrees. The bores were both tapered to the extent of .002 in., measurements being made at a point half an inch from tho top of the cylinder and at the base.
After the regrinding, which occupied about 50 minutes, measurements were again taken, the block being set up again on the surface plate. During the operation the diameter of No. 2 bore vas increased by .011 in. and that of No. 3 by .014 in. No. 2 cylinder was shown to be as truly cylindrical as Can be gauged with one of the best forms of Starrett internal micrometer. The difference of ovality of No. 3 was less than \.001 in. and the tapers in both bores were removed.
These results were very satisfactory, as can be seen by checking them with the figures of error given above. The artificially made score in No. 3 cylinder was not quite removed, but it was far deeper than would normally occur, and would otherwise have been eliminated. The surface of the metal after grinding was smooth to the touch and satisfactory for ordinary service, although the job had not been finished off with a fine Stone.
With regard to the general details of the Hutto grinder, it may be said mainly to comprise an operating stand, a driving spindle and a set of grinders with fine, medium, coarse and roughing stones. An ordinary electric drill can be used io drive the hone.
The appliance is comparatively simple to use and can be employed with the cylinder block in situ in the chassis. The only special skill required of the operator is an ability to read micrometer gauges, as the whole tool is arranged to facilitate the work as much as possible.
Three models of the tool are marketed for dealing with bores of various sizes, the largest being 5 ins, in diameter, and all sell at very reasonable prices, and can thus form part of the tool equipment of the great majority of operators of commercial motor vehicles.