Formulas
Calculating Pulley Speeds
In order to achieve precise speeds in order to cut a large range of metals, the use of pulleys is the easiest way. There is a simple way of determining the speed if you know the speed of the motor and the diameter of the drive pulley and the driven pulley. You simply take the motor speed, or RPM's (rotations per minute) and multiply that by the diameter of the pulley mounted on the motor, or "drive pulley". Then divide the product by the diameter of the cutter pulley, or "driven pulley":
(Speed of drive pulley • Diameter of drive pulley) ÷ Diameter of driven pulley
Example: My motor is 1725rpm, and has a 2" pulley mounted to it, and that is running to a 5" pulley. How fast is the 5" pulley rotating? To find out we use the above formula.
1725 • 2" = 3450
3450 ÷ 5" = 690
The 5" pulley is rotating at 690rpm.
Calculating Blade Speed
The blade rim speed, in ft/min (feet per minute), is determined by the blade diameter and the rotational speed, RPM (rotations per minute) of the blade.
Formulas:
ft/min = (blade dia. • 3.14 • RPM) ÷ 12
Example: 1 1/2" blade, 1400rpm
(1.5 • 3.14 • 1400) ÷ 12 = 550 ft/min
RPM = (12 • ft/min) ÷ (dia. • 3.14)
Example: 1 1/4" blade, want 100 ft/min
(12 • 100) ÷ (1.25 • 3.14) = 306RPM
Cutting speeds for Jewelers slitting saws.
|
Metal
|
Speed (ft/min)
|
|
Unalloyed Titanium
|
60 - 75
|
|
Med. Strength Ti Alloys.
|
40 - 55
|
| Hi Strength Ti Alloys | 25 - 40 |
| Regular Stainless Steel | 60 - 75 |
| Hi Strength Stainless Steel | 25 - 40 |
| Galvanized Steel | 100 - 150 |
| Regular Carbon Steels | 80 - 100 |
| Niobium | 80 - 120 |
|
Silver
|
80 - 100
|
|
Copper
|
80 - 100
|
|
Brass
|
100 - 150
|
|
Bronze
|
100 - 150
|
|
Aluminum
|
450 - 600
|
Quick reference table of suggested rpm speeds. Use detailed table farther below for exact speeds.
(SFM = ft/min)
|
Material
|
1. Mild Steel
2. Brass 3. Bronze |
1. Medium Tensile Steels
2. Cast Iron 3. Hard Brass & Bronze 4. Copper |
1. High Tensile Steel
2.Unalloyed Titanium | 1. Tool Steels 2. Medium Strength Stainless Steel 3. Medium Strength Titanium Alloys |
1. High Strength Stainless Steels
2. High Strength Titanium Alloys |
1. Aluminum & alloys. | |||
|---|---|---|---|---|---|---|---|---|---|
|
Diameter
of Saw |
SFM 100 - 150
|
SFM 80 - 100
|
SFM 60 - 75
|
SFM 40 - 55
|
SFM 26 - 40
|
SFM 450 - 600
|
|||
| RPM | RPM | RPM | RPM | RPM | RPM | ||||
| 1.25" | 380 | 275 | 205 | 145 | 100 | 1600 | |||
| 1.50" | 320 | 230 | 170 | 120 | 85 | 1330 | |||
| 1.75" | 275 | 196 | 145 | 105 | 72 | 1145 | |||
| 2.00" | 240 | 172 | 130 | 90 | 63 | 1000 | |||
| 2.25" | 212 | 155 | 115 | 80 | 56 | 890 | |||
| 2.50" | 190 | 135 | 100 | 72 | 50 | 800 | |||
| 2.75" | 175 | 125 | 92 | 66 | 45 | 730 | |||
| 3.00" | 160 | 115 | 85 | 60 | 42 | 665 | |||
| 4.00" | 120 | 85 | 65 | 45 | 32 | 500 | |||
The speeds given above are for the brand of saw blades we sell. Depending on the quality and manufacturer of your blades, results may differ.
For the self powered ringinator this table will help you use the right pulley combination to achieve a good cutting speed. The 275 shaft is the slow speed, the 1100 the fast speed. Pulley 1 is mounted on the shaft, and pulley 2 is mounted on the Ringinator cutter. Speeds assume a 1.5" OD blade is being used.
|
Shaft
|
Pulley 1
|
Pulley 2
|
RPM
|
SFM
|
|
275
|
1.5
|
4
|
103
|
41
|
| 275 | 2 | 4 | 138 | 54 |
|
275
|
1.5
|
2.5
|
165
|
65
|
| 275 | 2 | 3 | 184 | 72 |
|
275
|
3
|
4
|
206
|
81
|
| 275 | 2 | 2.5 | 220 | 86 |
|
275
|
2
|
2
|
275
|
108
|
|
275
|
3
|
2.5
|
330
|
129
|
|
1100
|
2.5
|
2
|
1375
|
540
|
How to use this table:
Find the desired ft/min figure you want in column 1. Find the outer diameter of the blade you are using in column 2, 3, 4, 5. Scroll down to see what RPM you need to have in order to get that ft/min with your blade.
Example: To cut titanium at 100ft/min, with a 1.5" blade, it needs to turn at 255rpm.
| ft/min | 1" | 1.25" | 1.5" | 1.75" | 2" | 2.25" | 2.5" |
| 10 | 38 | 31 | 25 | 22 | 19 | 17 | 15 |
| 20 | 76 | 61 | 51 | 44 | 38 | 34 | 31 |
| 30 | 115 | 92 | 76 | 66 | 57 | 51 | 46 |
| 40 | 153 | 122 | 102 | 87 | 76 | 68 | 61 |
| 50 | 191 | 153 | 127 | 109 | 96 | 85 | 76 |
| 60 | 229 | 183 | 153 | 131 | 115 | 102 | 92 |
| 70 | 268 | 214 | 178 | 153 | 134 | 119 | 107 |
| 80 | 306 | 245 | 204 | 175 | 153 | 136 | 122 |
| 90 | 344 | 275 | 229 | 197 | 172 | 153 | 138 |
| 100 | 382 | 306 | 255 | 218 | 191 | 170 | 153 |
| 110 | 420 | 336 | 280 | 240 | 210 | 187 | 168 |
| 120 | 459 | 367 | 306 | 262 | 229 | 204 | 183 |
| 130 | 497 | 397 | 331 | 284 | 248 | 221 | 199 |
| 140 | 535 | 428 | 357 | 306 | 268 | 238 | 214 |
| 150 | 573 | 459 | 382 | 328 | 287 | 255 | 229 |
| 160 | 611 | 489 | 408 | 349 | 306 | 272 | 245 |
| 170 | 650 | 520 | 433 | 371 | 325 | 289 | 260 |
| 180 | 688 | 550 | 459 | 393 | 344 | 306 | 275 |
| 190 | 726 | 581 | 484 | 415 | 363 | 323 | 290 |
| 200 | 764 | 611 | 510 | 437 | 382 | 340 | 306 |
| 210 | 803 | 642 | 535 | 459 | 401 | 357 | 321 |
| 220 | 841 | 673 | 561 | 480 | 420 | 374 | 336 |
| 230 | 879 | 703 | 586 | 502 | 439 | 391 | 352 |
| 240 | 917 | 734 | 611 | 524 | 459 | 408 | 367 |
| 250 | 955 | 764 | 637 | 546 | 478 | 425 | 382 |
| 260 | 994 | 795 | 662 | 568 | 497 | 442 | 397 |
| 270 | 1032 | 825 | 688 | 590 | 516 | 459 | 413 |
| 280 | 1070 | 856 | 713 | 611 | 535 | 476 | 428 |
| 290 | 1108 | 887 | 739 | 633 | 554 | 493 | 443 |
| 300 | 1146 | 917 | 764 | 655 | 573 | 510 | 459 |
| 310 | 1185 | 948 | 790 | 677 | 592 | 527 | 474 |
| 320 | 1223 | 978 | 815 | 699 | 611 | 544 | 489 |
| 330 | 1261 | 1009 | 841 | 721 | 631 | 561 | 504 |
| 340 | 1299 | 1039 | 866 | 742 | 650 | 577 | 520 |
| 350 | 1338 | 1070 | 892 | 764 | 669 | 594 | 535 |
| 360 | 1376 | 1101 | 917 | 786 | 688 | 611 | 550 |
| 370 | 1414 | 1131 | 943 | 808 | 707 | 628 | 566 |
| 380 | 1452 | 1162 | 968 | 830 | 726 | 645 | 581 |
| 390 | 1490 | 1192 | 994 | 852 | 745 | 662 | 596 |
| 400 | 1529 | 1223 | 1019 | 874 | 764 | 679 | 611 |
| 410 | 1567 | 1254 | 1045 | 895 | 783 | 696 | 627 |
| 420 | 1605 | 1284 | 1070 | 917 | 803 | 713 | 642 |
| 430 | 1643 | 1315 | 1096 | 939 | 822 | 730 | 657 |
| 440 | 1682 | 1345 | 1121 | 961 | 841 | 747 | 673 |
| 450 | 1720 | 1376 | 1146 | 983 | 860 | 764 | 688 |
| 460 | 1758 | 1406 | 1172 | 1005 | 879 | 781 | 703 |
| 470 | 1796 | 1437 | 1197 | 1026 | 898 | 798 | 718 |
| 480 | 1834 | 1468 | 1223 | 1048 | 917 | 815 | 734 |
| 490 | 1873 | 1498 | 1248 | 1070 | 936 | 832 | 749 |
| 500 | 1911 | 1529 | 1274 | 1092 | 955 | 849 | 764 |
| 510 | 1949 | 1559 | 1299 | 1114 | 975 | 866 | 780 |
| 520 | 1987 | 1590 | 1325 | 1136 | 994 | 883 | 795 |
| 530 | 2025 | 1620 | 1350 | 1157 | 1013 | 900 | 810 |
| 540 | 2064 | 1651 | 1376 | 1179 | 1032 | 917 | 825 |
| 550 | 2102 | 1682 | 1401 | 1201 | 1051 | 934 | 841 |
| 560 | 2140 | 1712 | 1427 | 1223 | 1070 | 951 | 856 |
| 570 | 2178 | 1743 | 1452 | 1245 | 1089 | 968 | 871 |
| 580 | 2217 | 1773 | 1478 | 1267 | 1108 | 985 | 887 |
| 590 | 2255 | 1804 | 1503 | 1288 | 1127 | 1002 | 902 |
| 600 | 2293 | 1834 | 1529 | 1310 | 1146 | 1019 | 917 |
| 610 | 2331 | 1865 | 1554 | 1332 | 1166 | 1036 | 932 |
| 620 | 2369 | 1896 | 1580 | 1354 | 1185 | 1053 | 948 |
| 630 | 2408 | 1926 | 1605 | 1376 | 1204 | 1070 | 963 |
| 640 | 2446 | 1957 | 1631 | 1398 | 1223 | 1087 | 978 |
| 650 | 2484 | 1987 | 1656 | 1419 | 1242 | 1104 | 994 |
| 660 | 2522 | 2018 | 1682 | 1441 | 1261 | 1121 | 1009 |
| 670 | 2561 | 2048 | 1707 | 1463 | 1280 | 1138 | 1024 |
| 680 | 2599 | 2079 | 1732 | 1485 | 1299 | 1155 | 1039 |
| 690 | 2637 | 2110 | 1758 | 1507 | 1318 | 1172 | 1055 |
| 700 | 2675 | 2140 | 1783 | 1529 | 1338 | 1189 | 1070 |
| 710 | 2713 | 2171 | 1809 | 1551 | 1357 | 1206 | 1085 |
| 720 | 2752 | 2201 | 1834 | 1572 | 1376 | 1223 | 1101 |
| 730 | 2790 | 2232 | 1860 | 1594 | 1395 | 1240 | 1116 |
| 740 | 2828 | 2262 | 1885 | 1616 | 1414 | 1257 | 1131 |
| 750 | 2866 | 2293 | 1911 | 1638 | 1433 | 1274 | 1146 |
| 760 | 2904 | 2324 | 1936 | 1660 | 1452 | 1291 | 1162 |
| 770 | 2943 | 2354 | 1962 | 1682 | 1471 | 1308 | 1177 |
| 780 | 2981 | 2385 | 1987 | 1703 | 1490 | 1325 | 1192 |
| 790 | 3019 | 2415 | 2013 | 1725 | 1510 | 1342 | 1208 |
| 800 | 3057 | 2446 | 2038 | 1747 | 1529 | 1359 | 1223 |