Table IX. Speed Of Grinding Wheels

Diameter of Wheel

(in.)

Maximum Revolutions

PER MlNUTE

Diameter of Wheel

(in.)

Maximum Revolutions per Minute

Diameter of Wheel

(in.)

Maximum Revolutions per Minute

1

19,000

5

4,400

14

1,580

1 1/2

12,500

6

3,700

16

1,380

2

19,000

7

3,160

18

1,230

2 1/2

8,800

8

2,770

20

1,100

3

7,400

9

2,460

22

1,000

3 1/2

6,300

10

2,210

24

920

4

5,500

12

1,850

26

850

for forcing the stream upon the wheel at the point of contact with the work by means of a small pump. For grinding milling cutters, reamers, taps, and similar tools, water is not used.

Table IX gives the maximum speeds of carborundum wheels of various diameters.

The accuracy of grinding renders the use of fine measuring tools a necessity. The micrometer caliper, especially with the vernier graduation, is best suited for this work.

While grinding is the only method of finishing some materials, such as hardened tool steel, and the most accurate way of finishing any kind of stock, its value as an economical method has only lately been recognized. The general method of finishing lathe work has been to take a roughing cut with about 1/16 inch feed, then a finishing cut with about 1/100 inch feed, and then file to remove the tool marks. In the majority of cases it is more economical, as well as more accurate, to take a roughing cut with 1/6 inch feed to within 1/32 inch of the size, and then finish by grinding.

In some cases it is possible to get excellent results by grinding to size directly from the bar without previous turning. (See Part V.)