327 Flashcards
A typical application for a dividing head is the milling of a
Gear
The index holes around the spindle of the dividing head are used in ____ indexing
Direct
If a dividing head has 24 holes around its spindle nose and you must cut four equally spaced notches in a workpiece, how far must you rotate the spindle
Six holes
If a dividing head has a 40:1 gear ratio, how many times must you turn the worm to move the spindle one quarter of a complete revolution?
10
How many crank turns are needed to index each of 12 equally spaced cuts on a workpiece? Use the formula: T = ^40/_N.
3^1/_3
Suppose indexing a workpiece requires 4 turns of the index crank. You will use a hole circle on the index plate with how many holes?
20
On a dividing head with a 40:1 gear ratio, one turn of the index crank moves the spindle how many degrees?
9
For simple angular indexing on a 40:1 dividing head, you can use an index plate circle with how many holes?
54
Compound indexing differs from simple indexing in that you
Turn the index plate itself
Differential indexing is similar to, but more accurate than, _____ indexing
Compound
What makes a universal dividing head different from a plain dividing head?
Its spindle nose can be swung up 90°
When you use a center in the dividing head spindle to hold a workpiece, you install the other center in the
Footstock
When mounting work on the dividing head center, you assure a positive flow of power from the dividing head spindle to the workpiece by using a
Driver and milling machine dog
When using a chuck to hold a workpiece on the dividing head, you can give the workpiece extra support with a
Steady rest
If you straddle mill a hexagonal workpiece, how many times must you position the work?
Three
Why should you insert a cap into the opening of the dividing head spindle?
To keep chips out of the spindle
When using the direct indexing method, you should NOT
Count the zero hole
To use the plain indexing method, the worm and worm gearing in the dividing head must be
Engaged
When plain milling, which side of a hexagonal workpiece should you mill after taking the first cut
The opposite side
The dividing head is useful for drilling holes
In a circle
Cutting the teeth in a spur gear is a type of
_____ milling.
Form
To mill spur gears, you should use ____ cutters
Special profile
Compute the outside diameter of a 30-tooth spur gear blank with a diametral pitch of six. Use the following formula
5.333 in.
Which of the following factors does NOT affect cutter selection for millling spur gears?
Whole tooth depth
Series of eight cutters each have been developed to cut gears with different numbers of teeth that have the same
Diametral pitch
To index the teeth of a large-diameter gear, use a
Rotary table
When measuring a newly cut gear over pins, you should use a
Micrometer
To check spur gear tooth thickness at the pitch circle, use a
Gear tooth vernier caliper
The distance between adjacent helices that are wound on a common cylinder is called the
Helix pitch
The lead of a helix is determined by the
Milling machine lead
To mill a helix, you must use change gears to link the lead screw of the milling machine with the
Dividing head worm shaft
If the ratio of change gearing is 1:1 and the lead of the milling machine is 10 in., a helix milling would have a lead of
10 in.
How many change gears usually make up a set?
4
In the change gear formula ^ 40/_40 x ^24/_60, how many teeth will the two driving gears each have?
40 and 24
In order to reverse the direction of gear rotation so that you can mill either a right- or left-hand helix, use a(n)
Idler gear
When using simple angular indexing to mill 15 teeth into a cylindrical workpiece, how far aprt must you space each tooth?
24°
In order to obtain the proper helix angle when milling a helical workpiece, you must swivel the
Machine table
Which of the following factors is NOT important for you to know about a helical gear you are milling?
Where it will be used
When milling helical gear teeth, you should NOT draw the cutter back through the work after a cut is complete because
You could damage the gear tooth surface
The tooth dimensions of spur gears are described by circular pitch. What measurement do you use to describe helical gear teeth?
Normal diametral pitch
What function does a cam perform?
They change the direction of motion of machine parts
The follower in a nonpositive cam system would NOT be controlled by
A groove in the cam
The distance that one cam lobe moves the follower from its starting point as the cam rotates is the
Cam rise
The total distance that a lobe on a uniform-rise cam would move the follower if the lobe extended a full 360° is the
Cam lead
When milling a plate cam, you need a dividing head and a
Vertical milling attachment
When milling plate cams, the dividing head spindle and the cutter CANNOT be
In the horizontal plane
When milling a uniform-rise cam with a short lead, the angle at which you set the vertical milling attachment determines the correct setting for the
• Dividing head spindle
On which side of the workpiece do you position the cutter when milling a short-lead cam?
Lower
If one lobe of uniform-rise cam covers 120° of the circumference and has a rise of 0.25 in., what is the cam lead?
0.75 in.
When milling nonuniform-rise cams, you should use
The incremental-cut methodl
