THREE:Success in Technical Training, as in other kinds of education, must depend greatly upon how well the general mode of thought among learners is understood and followed; and if the present work directs some attention to this matter it will not fail to add something to those influences which tend to build up our industrial interests.To point out some of the leading points or conditions to be taken into account in pattern-making, and which must be understood in order to manage this department, I will refer to them in consecutive order.
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THREE:They wont be any good, with that burst tirehell have to set down in water anyhow, Dick explained. Sandy nodded.
THREE:Judged upon theoretical grounds, and leaving out the mechanical conditions of operation, it would at once be conceded that a proper plan would be to move the lightest body; that is, if the tools and their attachments were heavier than the material to be acted upon, then the material should be moved for the cutting action, and vice versa. But in practice there are other conditions to be considered more important than a question of the relative weight of reciprocating parts; and it must be remembered that in solving any problem pertaining to machine action, the conditions of operation are to be considered first and have precedence over problems of strain, arrangement, or even the general principles of construction; that is, the conditions of operating must form a base from which proportions, arrangements, and so on, must be deduced. A standard planing machine, such as is employed for most kinds of work, is arranged with a running platen or carriage upon which the material is fastened and traversed beneath the cutting tools. [130] The uniformity of arrangement and design in machines of this kind in all countries wherever they are made, must lead to the conclusion that there are substantial reasons for employing running platens instead of giving a cutting movement to the tools.
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