Can internal gears be hobbed?

No. A hob is a large worm-shaped cutter that cannot fit inside a ring gear. Internal gears are made by gear shaping, broaching or, in high volumes, power skiving.

How accurate is gear shaping?

Usually about DIN 7–9 as cut. Better classes need gear grinding or honing after heat treatment.

Is gear shaping slower than hobbing?

Yes, for normal external gears, because the cutter only cuts on the down stroke. It is chosen where a hob cannot reach, not for speed.

Gear shaping job work: internal gears, splines, accuracy

Gear shaping cuts gear teeth with a cutter shaped like a gear that moves up and down while it and the blank turn together. Because the cutter only needs a small run-out space, it can cut internal gears, internal splines and gears close to a shoulder, which a hob cannot reach. For plain external gears, hobbing is usually faster.

Quick facts

Cuts: Internal and external spur and helical gears, splines, sprockets
Main advantage: Internal gears and gears next to shoulders
Typical accuracy: About DIN 7–9 as cut
Module range: About 0.5–8 on common machines
Cutter: Gear-shaped HSS or carbide cutter
Usually priced: Per piece, by module, teeth and face width

What it is used for

Internal gears for planetary gearboxes
Internal splines in hubs and couplings
Cluster gears where two gears sit close together
Gears next to a shoulder or flange
Sprockets, ratchets and special profiles with a special cutter

Gear shaping or gear hobbing?

	Gear shaping	Gear hobbing
Internal gears	Yes	No
Gears next to a shoulder	Yes, small run-out needed	Needs more clearance
Speed on external gears	Slower	Faster
Typical use	Internal gears, splines, cluster gears	Most external spur and helical gears

What to send the gear shop

Gear data: module, number of teeth, pressure angle, helix angle, profile shift
Internal or external, face width and run-out space available
Accuracy class (DIN, AGMA or IS) and inspection needed
Material and whether it is hardened after cutting
Over-pin or span measurement if your drawing gives it
Quantity and whether you supply turned blanks

Need gear shaping done?

Post your requirement free. Workshops that take your kind of work see it and get in touch. You only talk to the ones that fit.

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Related job work

Machines

Materials

Questions

Can internal gears be hobbed?: No. A hob is a large worm-shaped cutter that cannot fit inside a ring gear. Internal gears are made by gear shaping, broaching or, in high volumes, power skiving.
How accurate is gear shaping?: Usually about DIN 7–9 as cut. Better classes need gear grinding or honing after heat treatment.
Is gear shaping slower than hobbing?: Yes, for normal external gears, because the cutter only cuts on the down stroke. It is chosen where a hob cannot reach, not for speed.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 18 October 2026.