1. Yet another Boring class

2. Last time:
Straight hole
Taper hole
Contour hole

3. Boring head Adjustable tool holder for boring bar.
Has micrometer adjustment for bore size. Direct reading (a .010 change opens the hole NOT .020)

4. Tool construction Body attaches to arbor or tool holder in machine
Dial screw provides adjustment
Bar holder retains tool
Boring tool cuts metal

5. Boring Advantage One tool cuts infinitely many diameters
Single point tool is less likely to chatter
Hole is perfectly round
Disadvantage
Slow operation due to imbalance
“Cut and try” adjustment

6. Reaming v. Boring

7. A ream must remove equal amounts of metal from both sides of a hole, a boring head doesn’t need to. Hole location can be corrected with a boring head... not a ream

8. Tips from the good people at Criterion
Suggestions For Better Boring Head Performance
Cutting edge of tool must be on center line.
Tool sharpness for boring is more critical than for O.D. work.
Keep tool overhang to a minimum.
Use power feed whenever available.
Make allowances for "spring" or deflection when taking a heavy cut. Additional material will be removed on finish cut even though an additional adjustment has not been made.
When using carbide, avoid reversing or stopping the spindle in the middle of a cut. This can cause chipping or breakage.
For best surface finish spindle should be turning while tool is being retracted from the bore.
Avoid "bottoming-out" in a blind hole. A boring tool is not designed for end cutting.

9. Tip from your Fearless Leader
Take a cut heavy enough to “pre load” the tool for cutting accuracy. A “heavy” cut can be more accurate in some circumstances because tool deflection has been minimized.

10. What if we turn the bar around?