Tooling and hardware
Tooling and hardware calculators and charts
Keyseat depth from the top of the shaft = Y + H / 2: a 1 in shaft with a 1/4 in square key is cut 0.1409 in deep. The charts below cover the rest of the hardware you size at the machine.
Technical review pending. Formulas and values are cited. This notice comes down after a machinist review.
Tooling and hardware formulas
Y = (Ds - sqrt(Ds^2 - W^2)) / 2, depth = Y + H / 2 (keyway); W = n_w / 32, D = n_d / 8 (Woodruff); PD = N / DP, OD = (N + 2) / DP (spur gear); weight = V x density (metal weight); BCD = a / sin(180° / n) (wheel bolt pattern); ER collet grips N to N - 1 mm (ER16 to ER40)
| Symbol | Meaning | Unit |
|---|---|---|
| Ds | Shaft diameter (keyway) | in |
| D | Nominal key diameter (Woodruff) | in |
| W | Key width | in |
| H | Key height | in |
| Y | Chordal height: shaft surface above the keyseat edge | in |
| n_w, n_d | Woodruff key number digits: width (before the last two), diameter (last two) | none |
| N | Number of teeth (gear) or collet nominal size (ER) | teeth or mm |
| DP | Diametral pitch | teeth/in |
| PD, OD | Pitch and outside diameter | in |
| V | Volume | in³ or mm³ |
| BCD | Bolt circle diameter | in or mm |
| a | Distance between neighboring studs, center to center | in or mm |
| n | Number of studs | studs |
A 1.000 in shaft with a 1/4 in key: Y = 0.0159 in, depth 0.1409 in. A 36-tooth gear at 24 DP: PD 1.5000 in, OD 1.5833 in.
Source: ASME B18.3 and ISO 4762 (socket head cap screws); ASME B17.1 and B17.2 (keys, keyseats and Woodruff keys); ISO 299 (T-slots); DIN 6499 (ER collets); Machinery's Handbook (keyseat depth, gearing, densities).
Tooling and hardware tools
- Head diameter, head height, hex key, clearance drill and counterbore for inch and metric cap screws are on the socket head cap screw dimensions chart.
- Key size by shaft diameter, ASME B17.1 and DIN 6885-1, with the keyseat depth calculator, is on the keyway dimensions chart.
- Woodruff key numbers decoded, key heights and the matching keyseat cutter are on the Woodruff key chart.
- Metric T-slot dimensions, T-nut threads by slot width and T-slot cutters are on the T-slot dimensions chart.
- ER, 5C and R8 collet sizes, and the ER collet for any shank, are on the collet chart.
- Pitch and outside diameter, whole depth and center distance for DP and module gears come from the spur gear calculator.
- Weight of bar, plate and tube in common alloys comes from the metal weight calculator.
- The bolt circle from the distance between neighboring studs is on the wheel bolt pattern chart.
- The tap drill for a stud or T-nut thread is on the tap drill chart.
How to choose a chart
- You have a shaft diameter and need a key: the keyway dimensions chart (parallel keys). You have a key number stamped on a half-round key: the Woodruff key chart.
- You need to hold a part or a tool: a T-nut and stud on the table (T-slot dimensions), a collet in the spindle or chuck (collet chart).
- You need a fastener size or its counterbore: the cap screw chart; the hole for its thread: the tap drill chart.
- You are making a gear blank: the spur gear calculator for the outside diameter, then the keyway chart for the bore key.
- You are quoting or lifting stock: the metal weight calculator.
FAQ
What hex key fits a 1/4-20 socket head cap screw?
3/16 in. The head is 0.375 in across and 0.250 in tall.
What key goes on a 1 in shaft?
A 1/4 in square key; cut the keyseat 0.1409 in deep from the top of the shaft.
What does Woodruff key 808 mean?
8/32 = 1/4 in wide on an 8/8 = 1 in diameter; cut it with a #808 cutter.
Which ER32 collet holds a 1/4 in shank?
A 7 mm collet (7 to 6 mm) or a 1/4 in collet.
What T-nut fits a 14 mm T-slot?
M12 per DIN 508.
What is the pitch diameter of a 36-tooth, 24 DP gear?
1.5000 in, with a 1.5833 in outside diameter.
Last updated