1. Drilling, Boring, Reaming, and Tapping
Session 11

3. To Spot and Drill Work in a Chuck
Spotting ensures drill will start in center of work
Spotting tool used to make shallow, V-shaped hole in center of work
Provides start for drill to follow
Most cases hole spotted quickly using center drill
Extreme accuracy use spotting/ chamfering toolbit

4. Spotting Work in a Chuck
Mount work true in chuck
Set lathe to proper speed for type of material
Check tailstock and make sure in line
Spot hole with center drill or spotting tool

5. Drilling Work in a Chuck
Mount twist drill in tailstock spindle, drill chuck, or drill holder
Start lathe and set for proper RPM for workpiece and cutting tool
With tailstock spindle handle, move drill tip to end of part. Note reading on tailstock spindle.
Drill to desired depth, applying cutting fluid frequently

6. Spotting Work in a Chuck
To gage depth of hole, use graduations on tailstock spindle, or measure depth with steel rule
Withdraw drill frequently to break and/or remove chips and measure depth of hole
If hole is through, always ease force on feed as drill breaks through work

7. Boring
Operation of enlarging and truing drilled or cored hole with single-point cutting tool
For producing special-diameter holes
May be drilled in lathe, but not accurate
Drill become dull or hit hard spot and wander
Reamer will follow drilled hole and be off
For reamed hole to be straight and true
Drill, bore and then ream

8. To Bore Work in a Chuck
Mount work in chuck; face, spot, and drill hole approximately .060 in undersize
Select boring bar as large as possible and have it extend beyond holder only enough to clear depth of hole to be bored
Mount boring bar holder in toolpost on left-hand side of compound rest

9. Boring Work in a Chuck Set boring toolbit on center
Set lathe to proper speed and select medium feed
Start lathe and bring boring tool into contact with inside diameter of hole
Take light trial cut .250 inch long at right-hand end of work
Stop lathe and measure hole diameter with telescopic gage or inside micrometer

10. Boring Work in a Chuck
Determine amount of material to be removed from hole
0.10 to 0.20 in. for a finish cut
Set depth of cut for half amount of metal to be removed
Start lathe and take roughing cut
Slow lathe speed and increase feed if chatter

11. Boring Work in a Chuck
Stop lathe and bring boring tool out of hole without moving crossfeed handle
Set depth of finish cut and bore hole to size
Fine feed recommended for good surface finish
Check hole diameter

12. Reaming
Quickly obtain accurately sized hole and produce good surface finish
May be performed after hole drilled and bored

13. Reaming Work on a Lathe
Mount work in chuck; face, spot, and drill hole to size
Holes under .500 in – drill .015 in. undersize
Holes over .500 in. – drill .030 in. undersize
Holes true – bored .010 in. undersize
Mount reamer in drill chuck or drill holder
Holes .625 in and larger, fasten lathe dog near reamer shank and support tail

14. Reaming Work on a Lathe Set lathe to approximately half drilling speed
Bring reamer close to hole and lock tailstock in position
Start lathe, apply cutting fluid to reamer and slowly geed it into drilled or bored hole with tailstock handwheel

15. Reaming Work on a Lathe
Occasionally remove reamer from hole to clear chips from flutes and apply cutting fluid
Once hole reamed, stop lathe and remove reamer from hole
Caution: Never turn lathe spindle or reamer backward for any reason. This will damage reamer!

16. Tapping One method of producing an internal thread on a lathe
Tap aligned by placing point of lathe dead center in chuck end of tap to guide while tap turned by tap wrench
When tapping hole in lathe, lock spindle and turn tap by hand

17. To Tap a Hole in a Lathe Mount work in chuck; face and center drill
Select proper tap drill for tap to be used
Set lathe to proper speed
Drill with tap drill to required depth
Use cutting fluid if required
Chamfer edge of hole slightly larger than tap diameter

18. To Tap a Hole in a Lathe
Stop lathe and lock spindle, or put lathe in its lowest speed
Place taper tap in hole and support shank with tailstock center
With suitable wrench, turn tap, keeping dead center snug into shank of tap by turning tailstock handwheel

19. To Tap a Hole in a Lathe Apply cutting fluid while tapping hole
Back off tap frequently to break the chip
Remove taper tap and finish tapping hole with plug or bottoming tap

20. Grinding on a Lathe May do cylindrical and internal grinding
Toolpost mounted on lathe used for cylindrical and taper grinding
Internal attachment permits grinding of straight and tapered holes
Should be done on lathe only when no other machine available
Work rotates in opposite direction to grinding wheel so lathe must be equipped with reversing switch

21. Grinding a Lathe Center
Remove chuck or driveplate from spindle
Mount lathe center in headstock spindle
Set slow spindle speed
Swing compound rest to 30º with centerline
Protect ways of lathe with cloth or canvas and place pan of water below lathe center

22. Grinding a Lathe Center
Mount toolpost grinder and adjust center of grinding spindle to center height
Mount proper grinding wheel; true and dress
Start lathe, with spindle revolving in reverse
Start grinder and adjust grinding wheel until it sparks lightly against revolving center

23. Grinding a Lathe Center
Lock carriage in this position
Feed grinding wheel in .001 in. using crossfeed handle
Move grinder along face of center using compound rest feed at a steady pace

24. Grinding a Lathe Center
Check angle of center using center gage, and adjust compound rest if necessary
Finish-grind center
Polish center with abrasive cloth at high spindle speed if high finish desired