How to find the right Hobbing Cutters AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Hobbing Cutters
- Module or diametral pitch
- The hob's module (metric) or diametral pitch (inch) must exactly match the gear you are cutting. A hob generates only gears of its own pitch.
- Pressure angle
- Match the gear's pressure angle. 20° is the modern standard, and 14.5° appears on older inch gears. Gears with different pressure angles will not mesh correctly.
- Accuracy class
- Hobs are graded in quality classes (AA, A, B, C, per DIN 3968 or AGMA). Use AA or A for precision gears and B or C for roughing or general work. The hob's class limits the gear quality you can achieve.
- Hand and starts
- Choose right- or left-hand and the number of starts to suit the gear and machine. Single-start is standard for accuracy. Multi-start hobs cut faster but give lower accuracy, and the hand affects the setup angle.
- Bore and drive
- Match the bore (for example 22, 27, 32 or 40 mm, or 1 in / 1-1/4 in) and the drive type, keyway or clutch drive, to your hobbing arbor. Hobs need precise concentricity to cut accurate teeth.
- Tooth form
- Specify the profile: involute gear, spline, sprocket or worm wheel. Each profile is a different hob.
Brands that matter
- LMT Fette: German maker known for precision hobs.
- Gleason: Major gear-machine and hob manufacturer.
- Star SU: Gear-cutting tool specialist with production hobs.
- Somta: Offers HSS hobs and involute gear cutters with broad module coverage.
What to avoid
- Buying a hob without confirming whether the gear is specified by module or by DP. They are not interchangeable.
- Expecting a hob to work on a plain horizontal mill without a gear-train or indexing setup. Hobbing needs synchronized rotation.
- Unclassified import hobs for precision power-transmission gears.
Questions
Hob or involute gear cutter?
A hob generates any tooth count of a given pitch on a hobbing machine. An involute (form) gear cutter is used on a mill with a dividing head and is sold in numbered sets that each cover a range of tooth counts.