Chapter 14 study guide
What are the five ways of machining tapers on a lathe
-compound -offset tailstock -taper attachment -reamer -tool bit
A taper is isefull in machining technology because
-its wedging action permits it to drive cutting tools -it can be assembled and disassembled easily -it will automatically align a tool in a similar hole
Which of the two types of taper attachments requires disconnecting the cross-slide screw from the cross-slide nut
-plain taper attachment -telescopic taper attachment
A groove is cut at the point where the thread is to terminate and serves to
-provide a place to stop the threading tool after making a cut -permit a nut to run up to the end of the thread -end the thread
Cutting left hand threads requires
-that the carriage travels towards the tailstock -changing the lead screw rotation -pivoting the compound to the left
What is pitch equal to
1/ the # of threads per inch
At what spindle speed are screw threads cut
1/4th the speed thats used for conventional turning
The compound rest is set at to cut sharp threads
29°
On the thread the top and bottom are flat but the sides have a 29° included angle
Acme
What information must be known in order to cut a taper using a taper attachment
Angle Taper per foot Taper per inch
List advantages of a taper attachment
Can do internal and external
When cutting sharp v-threads a gage is used for grinding the cutter and setting it in position
Center
Tailstock offset can be determined visually by measuring the distance between the or betweem the witness lines on the base of the tailstock
Center points
Internal thread
Cut on inside surface of piece
External thread
Cut on outside diameter of piece
What is referred to as lead on a screw thread
Distance from one nut will travel in one complete revolution of a screw
Define pitch as it applies to thread terminology
Distance from one thread point to the next, measured parallel to thread axis
When cutting threads -profile inserts produce the best thread form and finish
Full
Pitch diameter
Imaginary diameter at the point where the widths of the thread and groove are equal
When cutting tapered threads to obtain a fluid or gas tight joint the threading tool must be positioned
In relation to the centerline of the taper
A taper is a section of material that
Increases in diameter at uniform rate
Major diameter
Largest diameter of thread
An accurate setover can be made by using the dial on the compound rest or cross slide or a dial indicator
Micrometer
The face of the thread dial rotates when the half nuts are
Not engaged
What are two major disadvantages of the offset tailstock method for cutting tapers
Only uses external Cut between centers
-profile inserts are most commonly used to cut threads because they can cut a range of thread pitches
Partial
On a single thread, the lead and are the same
Pitch
The must be known to measure thread accuracy with a thread micrometer
Pitch diameter
Of what is is a thread cutting stop
Provides a place to stop the threading tool but at the end of its cut and permits a nut to run up to the end of a thread
Always check the thread pitch after the first light cut with a
Rule and scrrw pitch gage
The offset tailstock method for turning tapers is also known as the tailstock method
Setover
A bar is a very accurately machined bar that is used in conjunction with gage blocks and sine tables to precisely measure angles
Sine
Minor diameter
Smallest diameter of a thread
Threads are usually employed to transmit motion
Square/acme
The most accurate method for cutting tapers is the
Taper attachment
A taper can be turned with the compound rest if the
Taper is converted to degrees
How are tapers specified
Taper per foot Taper per inch Angle Ratio
What are the two basic techniques used for testing the accuracy of a taper
Taper test gage Physically measuring
When cutting internal threads, tool infeed and removal from the cut are when cuttinf external threads
The reverse of those used
A thread dial is fitted to most lathes, what is its funtion
To know when to engage 1/2 nuts, which allow the tool bit to follow the origin cut
Screw threads have many uses, including
Transmitting motion Making measurements Making adjustments
What is a taper
Uniform rate increases or decreases on a shaft
The most accurate way to offset the tailstock center is to
Use a dial indicator
In machining technology what is a fishtail and what purpose does it serve
Used for grinding and setting the toolbit in position
What is on advantage a compound rest offers when used to cut tapers
Will cut external and internal tapers
Tailstock offset can be determined visually by measuring the distance between the center points, or between the on the base of the tailstock
Witness lines