Sharpening HSS Lathe Tool Bits

Sharpening HSS Lathe Tool Bits

What are typical rake and clearance (relief) angles for HSS tool bits?

See Figure A–1 and Table A–1.

Figure A–1. Tool bit nomenclature.

Material

Side Clearance

Front Clearance

Side
Rake

Back
Rake

Aluminum

12

8

16

35

Brass

10

8

5 to 24

0

Bronze

10

8

5 to 24

0

Cast Iron

10

8

12

5

Copper

12

10

20

16

Machine Steel

10–12

8

12–18

8–15

Tool Steel
(unhardened)

10

8

12

8

Stainless Steel

10

8

15–20

8

 

Table A–1. Clearance and rake angles in degrees for common metals.

What is the procedure for sharpening HSS general-purpose lathe tools?

Begin by dressing the grinding wheel. Next, look up the typical angles for the workpiece material, and then follow the steps in Figure A–2. Dip the tool in coolant frequently to keep it from overheating and annealing. Any discoloration on the bit indicates it may no longer be hardened. If this happens, consider starting over again from the beginning. Tool bit angles are not critical and most tools will cut material satisfactorily, just less effectively.

Figure A–2. Steps for sharpening HSS tool bits.

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