CHAPTER XXXIII. SHAPING MACHINES.

Shaping machines as machine tools occupy a middle place between planing and slotting machines; their movements correspond more to those of slotting machines, while the operation of the tools is the same as in planing. Some of the advantages of shaping over planing machines for certain kinds of work are, because of the greater facilities afforded for presenting and holding small pieces, or those of irregular shape; the supports or tables having both vertical¹ and horizontal faces to which pieces may be fastened, and the convenience of the mechanism² for adjusting and feeding tools.

Shaping machines are generally provided with adjustable³ vices⁴, devices for planing circular forms, and other details which cannot be so conveniently employed with planing machines. Another feature of shaping machines is a positive range of the cutting stroke produced by crank motion, which permits tools to be stopped with precision at any point; this admits of planing [136] slots, keyways, and such work as cannot well be performed upon common planing machines.

Shaping machines are divided into two classes, one modification⁵ with a lateral⁶ feed of the tools and cutter bar, technically⁷ called "travelling head machines," the other class with a feed motion of the table which supports the work, called table-feeding machines. The first modification is adapted for long pieces to be planed transversely, such as toothed racks, connecting rods, and similar work; the second class to shorter pieces where much hand adjustment is required.

An interesting study in connection with modern shaping machines is the principle of various devices called 'quick return' movements. Such devices consist of various modifications⁸ of slotted levers, and what is known as Whitworth's quick return motion.

The intricacy of the subject renders it a difficult one to deal with except by the aid of diagrams, and as such mechanism may be inspected in almost any machine fitting shop, attention is called to the subject as one of the best that can be chosen for demonstration⁹ by diagrams. Problems of these variable speed movements are not only of great interest, but have a practical importance not found in many better known problems which take up time uselessly and have no application in a practical way.

The remarks, given in a former place, relating to tools for turning, apply to those for planing as well, except that in planing tools greater rigidity¹⁰ and strength are required.

(1.) Why are shaping machines better adapted than planing machines for planing slots, key-ways, and so on?—(2.) What objects are gained by a quick return motion of the cutter bar of shaping machines?

1 vertical   

adj.垂直的，顶点的，纵向的；n.垂直物，垂直的位置

参考例句：

• The northern side of the mountain is almost vertical.这座山的北坡几乎是垂直的。
• Vertical air motions are not measured by this system.垂直气流的运动不用这种系统来测量。

2 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

3 adjustable   

adj.可调整的，可校准的

参考例句：

• More expensive cameras have adjustable focusing.比较贵的照相机有可调焦距。
• The chair has the virtue of being adjustable.这种椅子具有可调节的优点。

4 vices   

缺陷( vice的名词复数 )； 恶习； 不道德行为； 台钳

参考例句：

• In spite of his vices, he was loved by all. 尽管他有缺点，还是受到大家的爱戴。
• He vituperated from the pulpit the vices of the court. 他在教堂的讲坛上责骂宫廷的罪恶。

5 modification   

n.修改，改进，缓和，减轻

参考例句：

• The law,in its present form,is unjust;it needs modification.现行的法律是不公正的，它需要修改。
• The design requires considerable modification.这个设计需要作大的修改。

6 lateral   

adj.侧面的，旁边的

参考例句：

• An airfoil that controls lateral motion.能够控制横向飞行的机翼。
• Mr.Dawson walked into the court from a lateral door.道森先生从一个侧面的门走进法庭。

7 technically   

adv.专门地，技术上地

参考例句：

• Technically it is the most advanced equipment ever.从技术上说，这是最先进的设备。
• The tomato is technically a fruit,although it is eaten as a vegetable.严格地说，西红柿是一种水果，尽管它是当作蔬菜吃的。

8 modifications   

n.缓和( modification的名词复数 )；限制；更改；改变

参考例句：

• The engine was pulled apart for modifications and then reassembled. 发动机被拆开改型，然后再组装起来。 来自《简明英汉词典》
• The original plan had undergone fairly extensive modifications. 原计划已经作了相当大的修改。 来自《简明英汉词典》

9 demonstration   

n.表明，示范，论证，示威

参考例句：

• His new book is a demonstration of his patriotism.他写的新书是他的爱国精神的证明。
• He gave a demonstration of the new technique then and there.他当场表演了这种新的操作方法。

10 rigidity   

adj.钢性，坚硬

参考例句：

• The rigidity of the metal caused it to crack.这金属因刚度强而产生裂纹。
• He deplored the rigidity of her views.他痛感她的观点僵化。