Sawing

1. Sawing

2. Reciprocating saws (power hack saw) • being replaced by horiz band saws • only cuts in one direction • up to 24” x 24”

3. Band machines • continuous band = high cutting efficiency • blade has large number of cutting points so wear is distributed • no limit to length, limitation is frame size • 3 types

4. 1. Horizontal band saw • mainstay of production stock cutoff

6. Swing stock stop clear before cutting so work does not bind

7. If possible, don’t cut short pieces

8. Support both ends of vise for short pieces

9. Proper clamping

10. 2. Vertical band saw

11. Cuts narrow kerf

12. Cuts circular patterns (contours)

13. Table can be tilted 10 degrees left and 45 degrees right

14. Feed can be by hand or mechanical • generally not used to cut round stock

15. Keep guidepost guard about 1/4” above work piece

16. Cutting a blade to insert in a hole in a work piece

17. 3. Tilt frame band saw • band blade is vertical and tilts from side to side • good for angle cuts

18. Cold saw - circular saw accurate cuts to within .002”

19. Abrasive cutoff saw • uses circular abrasive wheel • abrasive particles act like a saw tooth • seldom used for general stock cutting • used more for very hard materials

20. Advantages of abrasive cutoff saw • speed (up to 20,000 sfpm) • ability to cut non metals

21. Abrasive wheels made from: • a. aluminum oxide - for most metals • b. silicone carbide - non metallic materials such as stone • c. diamond abrasives - hard materials like glass

22. Feed Rates • too fast - heat generated by friction will dull tool • too slow - results in early dulling

23. Setting feeds and speeds • Generally harder tougher materials = lower cutting speeds • Charts • Experience

24. Saw blades • at least 3 teeth in contact with work thin material = more teeth per inch • thick = fewer teeth per inch

25. Blade materials • carbon steels • high alloy steels • tungsten carbide tipped teeth

26. Terms

27. Kerf = width of cut

28. Width = distance from tip of the tooth to the back of blade

29. Gage = thickness behind set (teeth) of blade • reciprocating saw blades - up to .250” thick • band saw blades - up to .035” thick • pitch = teeth per inch

30. Pitch = Teeth per inch

31. Tooth forms • standard - accurate & smooth finish • skip - gives additional chip clearance • hook - faster cutting due to positive rake angle

32. Set • Total distance from tip of tooth on one side to tip of tooth on other side • Provide clearance for back of blade

33. Set patterns • raker - for general sawing • straight • wave - where cross sectional shape of the work piece varies • raker and wave most common

34. Selecting a blade depends on: • material to cut • thickness of material • cross sectional shape • some machines have a job selector for assisting

35. Cutting fluids are important for: • carrying chips away • cooling • lubricating

36. Installing blades • tighten until a ring is heard when tapping • make sure teeth point in proper direction • check for proper tracking • recheck band tension after a few cuts because blade will seat and stretch during break-in period

37. Installing blades (cont.) • adjust blade guides close to the blade • chip brushes functioning properly? • wear gloves when installing blades (usually don’t wear gloves in machine shop)

38. Blades can be ordered already welded or you can cut and weld your own from a spool

39. Misc. Operations:

40. Band filing

41. Spiral saw blades - intricate contours in any direction

42. Friction sawing