1. Metal-Cutting Saws 1

2. 35-2
Metal-Cutting Saws
First crude saw closely followed origin of stone ax and knife
Sharp edges of stones were serrated or toothed
Cut by scraping away particles of object
Great improvement followed the appearance of copper, bronze, and ferrous metals
Today steel available for saw blades 2

3. Types of Metal Saws

4. 35-4
Objectives
Name five types of cutting-off machines and state the advantage of each
Select the proper blade to use for cutting various cross sections
Install a saw band on a horizontal bandsaw
Use a bandsaw to cut off work to an accurate length

5. Methods of Cutting Off Material
35-5
Methods of Cutting Off Material
Five most common methods of cutting off material
Hacksawing
Bandsawing
Abrasive cutting
Cold sawing
Friction sawing 5

6. Power Hacksaw Reciprocating type of saw
35-6
Power Hacksaw
Reciprocating type of saw
Frame and blade travel back and forth
Pressure applied automatically on forward stroke
Limited use in machine shop work
Usually permanently mounted to floor 6

7. 35-7
Horizontal Bandsaw
Flexible, belt like "endless", blade that cuts continuously in one direction
Thin, continuous blade travels over rims of two pulley wheels and passes through roller guide brackets
Support blade and keep it running true
Popular for high production and versatility 7

8. 35-8
Abrasive Cutoff Saw
Cuts by means of thin, abrasive wheel revolving at high speed
Well suited for cutting most metals and materials such as glass and ceramics
Can cut to close tolerances
Can be performed under dry conditions
Use of cutting fluid keeps work and saw cooler and produces better surface finish 8

9. Cold Circular Cutoff Saw
35-9
Cold Circular Cutoff Saw
Uses circular blade similar to one used on wood-cutting table saw
Generally made of chrome-vanadium steel
Carbide-tipped blades used for some applications
Suited for cutting aluminum, brass, copper, machine steel, and stainless steel 9

10. 35-10
Friction Sawing
Burning process by which saw band (with or without) saw teeth, is run at high speeds to burn or melt its way through metal
10,000 to 25,000 sf/min
Cannot be used on solid metal
Amount of heat generated
Excellent for cutting structural and honeycombed parts of machine or stainless steel 10

11. 35-11
Saw Blades
Commonly made of high-speed tungsten and high-speed molybdenum steel
Hardened completely for power hacksaw
Flexible blades on bandsaws have teeth hardened
Manufactured in various degrees of coarseness, ranging from 4-14 pitch
10-pitch blade used for general-purpose sawing
Always select saw blade as coarse as possible
Always have two teeth of blade in contact with work at all times 11

12. 35-12
Sawing
Important that correct type and pitch of saw blade be selected and run at proper speed
Blades
Finer tooth when cutting thin cross sections and extra-hard materials
Coarser tooth used for thick cross sections and soft, stringy material
Speed
Should suit type and thickness of material
Too fast will dull saw teeth quickly 12

13. Contour Bandsaw Parts and Accessories

14. 36-14
Objectives
Name the main operative parts of a contour-cutting bandsaw and state the purpose of each
Select the proper tooth form and set for any cutting application
Calculate the length of a saw band for a two-pulley machine

15. Vertical Bandsaw Latest machine tool to be developed
36-15
Vertical Bandsaw
Latest machine tool to be developed
Early 1930s
Widely accepted by industry
Fast and economical method of cutting metal and other materials
Continuous cutting action on workpiece 15

16. Advantages of the Vertical Bandsaw
36-16
Advantages of the Vertical Bandsaw 16

17. Advantages of the Vertical Bandsaw
36-17
Advantages of the Vertical Bandsaw 17

18. Advantages of the Vertical Bandsaw
36-18
Advantages of the Vertical Bandsaw 18

19. Contour Bandsaw Parts Fabricated from steel Basic parts Base Column
36-19
Contour Bandsaw Parts
Fabricated from steel
Basic parts
Base
Column
Head 19

20. Bandsaw Common Applications
36-20
Bandsaw Common Applications
Notching
Sections of metal removed in one piece
Slotting
Quick and accurate without expensive fixtures 20

21. Bandsaw Common Applications
36-21
Bandsaw Common Applications
Three-dimensional shaping
Simply follow layout lines
Radius cutting
Internal or external contours
Internal sections removed in one piece 21

22. Bandsaw Common Applications
36-22
Bandsaw Common Applications
Splitting
Accomplished quickly with minimum waste
Angular cutting
Work clamped at any angle
Table may be tilted 22

23. Coolants Power-feed models have cooling system Mist coolant system
36-23
Coolants
Power-feed models have cooling system
Circulates and discharges coolant against faces of blade and work
Mist coolant system
Uses air to atomize coolant and direct it (efficient)
Recommended for high-speed machining of nonferrous metals
Grease-type lubricants and coolants may be applied directly to blade on machines with no system

24. Power Feed Work and table fed toward blade by hydraulic system
36-24
Power Feed
Work and table fed toward blade by hydraulic system
Fixed-table machines use gravity to provide steady mechanical feeding pressure
Allows operator to use both hands to guide
Work forced into blade by cables, pulleys, and weights
Force
Varied up to about 80 lb. (regular lbs) 24

25. Tooth Forms Precision (regular) Claw (hook) Buttress (skip)
36-25
Tooth Forms
Precision (regular)
Most generally used
0º rake angle, 30º back clearance
Used for fine finish
Claw (hook)
Positive rake on cutting face
Faster cutting, longer lasting than buttress
Buttress (skip)
Teeth spaced farther apart
Tooth angles same as precision teeth
Used on thick work sections 25

26. Pitch Numbers of teeth per standard reference length
36-26
Pitch
Numbers of teeth per standard reference length
Inch standard = No. teeth/inch
Metric standard = No. teeth/25 mm
Thickness of material to be cut determines pitch of blade to use
Coarse: thick, Fine: thin
Two teeth in contact with work at all times 26

27. 36-27
Set
Amount teeth offset on either side of center to produce clearance for back of band
Wave set
Group of teeth offset to right and next to left
Structural steel or pipe
Straight set
One tooth offset to right and next to left
Light nonferrous castings
Raker set
One tooth offset to right, one to left, and third tooth straight 27

28. Width Wide blade used for straight, accurate cuts
36-28
Width
Wide blade used for straight, accurate cuts
Narrow blades used to cut small radii
Radius charts show proper width of blade are found on all bandsaws
Choose widest blade that can cut smallest radius 28

29. Gage Thickness of saw blade Thick blades stronger than thin blades
36-29
Gage
Thickness of saw blade
Thick blades stronger than thin blades
Thickest blade possible should be used for sawing tough material
Standardized according to blade width
½ in wide are .025 in. thick
5/8 in. and ¾ in. wide are .032 in. thick
1 in. wide are .035 in. thick 29

30. 36-30
Job Requirements
Bandsaw operator should be familiar with various types of blades
Select one that will do job to specified finish and accuracy at lowest cost
Table 36.1 in text provides guide 30

31. Calculate Length of Saw Blade
36-31
Calculate Length of Saw Blade CD
Packaged in coils 100 to 150 ft. in length
Cut length required and weld ends
Twice center distance between each pulley and add it it one pulley's circumference D
Blade length = 2 (CD) + µ D 31