your cleaning procedure according to the type of material you are cutting. With aluminum or other soft, clean materials, you probably won’t damage anything by using air. With hard, gritty, or abrasive material, it makes sense to use a brush and paper towel to wipe the grit off the machine’s ways. If you use sandpaper or other abrasives in or around your machine, wipe the grit off with a paper towel or rag before moving the table. (See Fig. 1-18)
With that in mind, get yourself an air nozzle that puts out some volume so you can blow chips off quickly.
Figure 1–18 Wipe gritty material from the ways of machines to avoid wearing them out prematurly.
| Suggestions for Working Quickly | ||
| 1. | Turn man-time into machine time. | |
| 2. | Have lots of tools. | |
| 3. | Use dedicated tools. | |
| 4. | Make all your parts the same. | |
| 5. | In a milling machine, when practical, use a large enough cutter to cut across the entire surface of the part in one pass. | |
| 6. | Turn the shanks of your larger drill bits down to common collet sizes. | |
| 7. | Use stub drills. | |
| 8. | Use a speed chuck in a conventional milling machine. | |
| 9. | Use a slide fixture in a conventional mill to drill holes. | |
| 10. | Use chip color to determine speed, feed, and depth of cut in ferrous materials. | |
| 11. | Rough ugly. | |
| 12. | Work your way up to a heavy roughing cut. | |
| 13. | Avoid using a single flute fly cutter to rough with. | |
| 14. | Try to rough as close to final size as practical. | |
| 15. | Work your machine hard when roughing, but do it the right way. | |
| 16. | Place your hand on a milling machine table to gauge the pressure of a cut. | |
| 17. | Make parts with as few setups as possible. | |
| 18. | Use air mist to prolong the life of your cutter and increase stock removal rates. | |
| 19. | Go as fast as you dare in aluminum and other easily machined materials. | |
| 20. | Bore holes with a mill like you would with a lathe. | |
| 21. | Power tap blind holes that are drilled deep enough. | |
| 22. | Saw your raw stock about a tenth of an inch larger than finished size. | |
| 23. | Use a cold cut saw for cutting off bar stock. | |
| 24. | When running multiple parts do one operation at a time in a tool room lathe | |
| 25. | Change small lathe parts when using a collet closer without turning off the spindle. | |
| 26. | Stack parts when you can. | |
| 27. | Stack parts on edge for drilling and tapping. | |
| 28. | Consider buying pre-squared blocks for high quantity runs. | |
| 29. | Use an end mill in the lathe to rough out a flat bottom hole. | |
| 30. | Keep a box of loose drill bits handy. | |
| 31. | Keep a large assortment of T-nuts on hand. | |
| 32. | Avoid clearing your cutter to go back for another cut. | |
| 33. | Don’t bother removing a built-up edge on a lathe tool when roughing. | |
| 34. | Drill deep holes in a conventional lathe quickly by sliding the tailstock. | |
| 35. | Deburr rough edges with a small, angle-head die grinder. | |
| 36. | To save a little time, avoid turning off a conventional milling machine to change parts. | |
| 37. | Cut the diameter of a lathe part instead of the face to remove material quickly. | |
| 38. | Cut arcs by hand in a conventional milling machine by using a dowel pin as a center pivot. | |
| 39. | Cut spherical shapes with a conventional lathe. | |
| 40. | Use short, stubby end mills whenever possible. | |
| 41. | Use a hex cutter for deep arrow slots. | |
| 42. | Measure stock one time only to rough in a feature. | |
| 43. | Avoid tilting the head of a mill when possible. | |
| 44. | Take your drawing with you to the stock room. | |
| 45. | Use a high volume air nozzle. | |
| 46. | Calculate chip load and surface feet per minute. | |
| 47. | Tidy up your desk or bench by handling objects one time only. | |
| 48. | Make notes about machines you don’t often use. |
46.Calculate chip load and surfaces feet per minute.
On conventional machines, I generally set cuts based on feel and intuition. Later I may run numbers to get a quantitative idea of what’s going on.
Two important numbers in machining are chip load (thousandths per tooth) and surface feet per minute, or SFM, which is a measure of the rate at which material slides across a cutting edge. For more in-depth discussion of these formulas, see Chapter 15.
Chip load in a milling machine = Feed Rate / RPM × No. of Flutes
Surface Feet Per Minute (SFM) = RPM × Dia. × .262
47.Tidy up your desk or bench by handling objects one time only.
This suggestion sounds simplistic, but is effective. When tidying up or putting things away, there is a human tendency to pick something up and set it down again somewhere else. Avoid that tendency. Whatever you pick up to put away should be put away the first time you handle the object.
48.Make notes about machines you don’t use often.
Machines you don’t use too often may take some time to get used to after you’ve been off them for a while. Make written notes on the ins and outs of any particular machine so you’ll be able to get back up to speed quickly.
Conclusion
As you can see, there are various approaches to running jobs and setting cuts. Ideally, machinists strive for the most aggressive cut they can get away without quickly ruining cutters or crashing. Often, the limiting factor in terms of aggressive cutting turns out to be the rigidity of the setup and the strength of the cutter. An additional factor to consider is that parts become weaker as they’re machined.
Machinists have to be intuitive stress engineers. They constantly have to make judgments about the aggressiveness of cuts based on the type of material they’re cutting, the rigidity of the
