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30: M A R | N Ej R BV I i. We UNIFORM SPECIFICATIONS » Mr. W: D. Forbes'. paper: upon "Uniform Specifications" read at' the recent. meeting of the Society of Naval Architects &' Marine Engineers in New York willbe read with' great: in- terest by contractors. It was as follows: "Sometime since, a paper was read before this association on: *The Interchangeability of Units for Sea Use' The idea was favorably received. The advantage of: interchangeability of parts as:-well as units is certainly recognized as a further- ance of engineering work. With these facts in mind, it is now proposed to carry the idea further and discuss the advantages of interchangeability of specifications, It must be admitted that: there is no sound reason why a steam engine, for instance, should-not function equally well if ordered: by one person or by another, provided: 'running conditions: are the: same. It would:seem:that:if.a corporation could accept an/engine com- plying merely with certain restrictions of 'weight, space and revolutions, without 'any regard to the material used, except that it be. 'first-class,' another 'could accept it: without going into the detail of babbitt metal, steel, or composition entering into its make up. It'is self-evident that a firm constantly bend- ing its attention to the manufacture of a high grade machine will understand. more thoroughly what 'is: needed in its con- struction'than an outsider: "Tt wall; of course, be: admitted that there are certain: de- mands: which: must be met 'in special places, as, for instance, navali:or:;merchant marine. Some are liberal 'in permitting manufacturers to use well tried: material: not exactly meeting specifications, and some will pass engines which do not fill the requirements as laid down 'in:specifications, but it is held that such :procedure is manifestly wrong. The function of a speci- fication 'is. td specify ;. it should not demand information which isa trade secret or which cannot be imparted without practical demonstrations and experience, or something which prohibits obtaining the desired results,..as for-instance that 'a hard sound: casting for: cylinder "be: furnished,' and 'exacting that no scrap metal be used, and that the mixture of iron be clearly giyen. No foundryman would be willing to undertake to make a close, hard,-iron cylinder without. scrap, and few are willing to. instruct others how to make: castings, and very few, to tell: the truth, are able to impart the knowledge. "Some buyers are very exacting about the babbitt metal, allowing only 2 per cent of lead, while others make no demand as.to this metal. A babbitt with but 2 per cent of lead is good for certain positions, but is not good for high speed work, and if pounding in is required, at least' 20 per cent of lead should be allowed. Pounding babbitt should be resorted to only to get a solid box; making hard spots in a babbitt bear- ing. by pounding is self-evidently a bad plan. "A pig of babbitt is supplied, and a chemical analysis shows it to meet the specifications, bearings are poured of it, and it is supposed that the desired mixture is used, but this is not so, as a chemical analysis of the babbitt from the béaring will show that the original: mixture does not exist,'as much of the tin'has gone up the chimney in melting. Here the buyer expresses a desire for a certain mixture, and then knowingly' accepts something else. "Nickel steel is an-article often: demanded in engine -speci- fications; its value cannot be questioned in many cases on account of its strength, but on small forgings there seems to be endless strains set up which no amount 'of annealing removes. Some articles seem impossible to make of this ma- terial when of small area, and retain their shape; whether ground or turned the springing seems to continue even when no forging is done. In nickel crank shafts' of about 3 in. in diameter, great difficulty is encountered by the continual spring of the forging as the several cuts are taken, and very true cranks are hardly obtainable. That crank pins must line and be true cylinders, is a perquisite of an enduring engine, and as in small engines it is quite easy to d&sign a shaft which if made of but ordinary machinery steel will stand all possible strains and service, a party who does not demand nickel steel is getting by far the more reliable articles. "Many compositions demanded by the buyers are too hard, the formule 88-10-2 mixture is reported to be popular mainly because it-is never furnished. It is a mixture which is very difficult' to 'machine, and for high speed bearing is never employed in commercial work.. In the bearings of a wood working machine, where lasting qualities are of great moment, nothing but babbitt will be found with never less than 20 per cent of lead in it. In fact it is held that the size.of bearing has. far more to do with its lasting qualities than the material of which it is made. "Probably the question of what is a right and what is a left-hand engine will be a continual source of argument with many, unless the turbine comes to the rescue; but one would suppose that this could be clearly settled by each engine build- er. In one specification this is to be found: 'When a person is standimg at the commutator end and the direction of rota- tion is against the clock, the plant is right-handed.' While this is incorrect, it is a clear description of what the parties choose to call a right-hand engine, and one which could be furnished without further question. "The wording in some specifications is hard to understand, as for instance the following: 'The lower side of the combi- nation bed plate to be planed perpendicularly to the line of the stroke of the engine. This might mean that the bed plate -is to be set on edge in the planer and its bottom planed with a down feed--all it really means is that the bed plate is to be finished on its bottom. "As to what may be properly termed 'first-class' in' material is open to debate, but certainly anything may be properly called so which has proved satisfactory in the past, and met the re- quirements of strength and endurance for a long period. "That weight, space, and lasting qualities are matters of great moment, especially aboard ship, is admitted, and it is, of course, necessary to have a clear statement of what is al- lowable, and to know the exact conditions under which a ma- chine is to operate either afloat or ashore, before a design can be made or a bid given. It is sometimes claimed that a bond guarantee should be furnished by a manufacturer and he' be left free to select all materials. and designs, and some very successful buyers do thus order and accept articles, and it is hard to see why all should not adopt the same system;. but failing this, why not adopt the other system of nominating everything and having some uniform chemical or physical tests which would pass all material, no matter where it goes or for whom it is ordered. Either condition would result in work being gotten out with less loss of time and at less ex- pense, but one or the other system should be general. "If the latter system is decided upon, it could only be with the one desire that the very best is to be obtained; no other possible motive could be ascribed to its advocates; but it places the buyer in the position of nominating what should be used and then holding those who furnish it responsible, not.a tenable position; while if the former system is adopted, the desire that, the best be given is far more likely to result in success, as there is then no possible. division of responsi- bility, and. the experience of those most interested would be made. available. "It would. certainly seem that the bonded guarantee system would: present to the navy allurements. The. endless detail now imposed on officers as to material. would be done:away with. The experience of the navy is free as air to us and all nations, and this, coupled to commercial experience and engix neering ability, must result in' manufacturers turning . out mechanical contrivances which wiil fill all requirements, as their very existence would depend on so doing, "The necessary time now required for inspection in detail