Custom gears and gear sets for robotics
A custom gear is made to a drawing or specification for one application, rather than chosen from a stock catalog.
Pico supplies spur, helical and internal ring gears, pinion shafts and matched gear sets for robot joints, grippers and drives, made to your design. Work starts with a prototype or pilot batch, then moves into repeat supply.
At a glance
| Topic | How it works |
|---|---|
| Gear types | Spur, helical and internal ring gears, planetary gear sets, pinion shafts, matched sets |
| Starting point | Your drawing, CAD model or gear data. No catalog, no stock parts |
| Quantities | Prototype or pilot batch first, then repeat supply |
| Manufacturing route | Chosen per part. Specialized steps may come from outside suppliers, stated in the scope |
| Inspection | Plan and acceptance criteria agreed before the pilot build |
| Country of origin | US manufacturing can be specified as required or preferred and is evaluated in the scope |
Which custom gears do we supply for robots?
The gears Pico supplies for robot transmissions, and the design point to settle for each:
| Gear type | Where it appears in a robot | Design notes |
|---|---|---|
| Spur gear | Parallel-shaft stages, gripper drives | Simple to make and inspect, no axial thrust; louder than helical at speed |
| Helical gear | Stages where noise matters | Gradual, quieter mesh, but axial thrust the bearings must carry; specify helix angle and hand |
| Internal ring gear | Ring of a planetary stage | Often combined with the housing, which saves a part but ties gear quality to the housing |
| Planetary gear set | Joint reducers and actuator stages | Tooth counts must meet the assembly conditions; check them with the planetary gear ratio calculator |
| Pinion shaft | Motor-side reducer input | Teeth cut on the shaft: no keyed joint, and suits pinions too small for a bore |
| Matched gear set | Pairs that run together | Made and inspected as a set, so the mesh is checked as it will run |
For complete stages, see custom planetary gearboxes for robot joints. For how reducer types compare, see robot joint gearboxes and reducers.
How do you specify a custom gear?
Put these on the drawing or in a gear data table:
- Module or diametral pitch: module m in millimeters for metric gears, DP in teeth per inch of pitch diameter for inch gears.
- Pressure angle: 20 degrees is the most common. Mating gears share module and pressure angle.
- Tooth count, face width and profile shift.
- Helix angle and hand for helical gears (external pairs on parallel shafts have opposite hands).
- Quality class and the standard it refers to (ISO 1328-1, ANSI/AGMA ISO 1328-1, or the older AGMA 2015 or AGMA 2000), since class numbers are not interchangeable and AGMA 2000 numbers run the opposite way.
- Material and heat treatment, with hardness and case depth where case hardened.
- Bore and drive feature (keyway, spline or integral shaft) and the inspection report you need.
m = 25.4 / DPInch diametral pitch to metric module in millimeters: 20 DP is module 1.27.
d = m·zda = m(z + 2)df = m(z − 2.5)db = d·cos αPitch, tip, root and base diameters for z teeth at pressure angle α, standard proportions, no profile shift. External gears; for an internal ring gear da = m(z − 2) and df = m(z + 2.5).
a = m(z1 + z2) / 2Center distance of an external pair. The pair drawn above is module 1.5: d = 54 mm and 27 mm, a = 40.5 mm.
Check small pinions for undercut. The theoretical minimum tooth count without it is 2 / sin²α, about 17 teeth at 20 degrees with no profile shift, which is why smaller robot pinions often carry a positive profile shift.
How are prototype and pilot gears made?
The route is chosen per part, from the gear data, material, quantity and quality class:
| Process | Typical use |
|---|---|
| Hobbing | External spur and helical gears, pinion shafts |
| Shaping | Internal ring gears, and teeth next to a shoulder where a hob cannot run out |
| Power skiving | Internal and external teeth in a continuous cut |
| Grinding | Finishing after heat treatment when the quality class requires it |
| Wire EDM | Some prototype profiles, without a gear cutting tool |
| Heat treatment | Through hardening, carburizing or nitriding where the load needs it |
| Machining or molding | Polymer gears: machined for prototypes, molded at volume |
| Powder metal | A volume route once the design is stable, as it needs dedicated tooling |
Some processes, such as gear cutting, heat treatment, or molding, may come from outside suppliers. The proposed route, and where each step happens, is stated in the scope we send you. If US manufacturing is required or preferred, mark it in the inquiry; US gear manufacturing and sourcing explains how it is evaluated.
How is gear quality checked?
The inspection plan follows the drawing. It can cover:
- Dimensions: bore, outside diameter, face width and datum features.
- Tooth thickness, by measurement over pins or balls.
- Runout relative to the bore or datum axis.
- Profile and lead checks, where the drawing requires them.
- Hardness and case depth for heat-treated gears.
Where each check is performed, in-house or at an outside lab, is stated in the scope.
For precision gears, the quality class on your drawing sets the tolerances these checks are measured against. Pico does not publish a class of its own; the engineering review confirms whether and how the proposed route can meet yours. Acceptance criteria are agreed before the pilot build.
When should a robot gear be plastic, metal or hybrid?
Steel gears are the usual choice where torque is high and sustained, temperatures rise, or backlash must stay tight as conditions change. Polymer and hybrid gears can reduce mass, noise and lubrication in lighter-load stages such as grippers, and they are evaluated for pilot projects against the duty cycle. Materials and design rules are covered on custom plastic and hybrid gears for robots.
How do custom gears move from prototype to repeat orders?
Every gear program follows the same four steps from requirement to repeat supply:
- Share the requirement: application, drawing or gear data, quantity and timing.
- Define the build: we review feasibility, material, route, inspection and scope, and send a written proposal before anything is made.
- Start with a pilot: a prototype or initial batch with agreed acceptance criteria.
- Scale what works: repeat orders with the same drawings, inspection plan and point of contact.
Joint housings, bearing carriers and shafts and gearbox subassemblies and kits can join the same scope. When the drawing is ready, send your gear data to start a project.
Questions
Do you sell stock gears?
No. Pico supplies gears made to your drawing or specification. If a stock gear fits your design, a catalog supplier is usually the faster route.
Do you cut the gears yourselves?
Some processes, such as gear cutting, heat treatment, or molding, may come from outside suppliers. The proposed route, and where each step happens, is stated in the scope we send you.
What gear quality class can you hold?
We do not publish a quality class. Put the class your design needs on the drawing, and the engineering review confirms whether and how the proposed route can meet it and how it will be inspected.
Can you work in metric module and inch diametral pitch?
Send the specification in the system your design uses, and the quote follows that specification.
What should we send to get a gear quoted?
A drawing or CAD model, the gear data (tooth count, module or pitch, pressure angle, face width, quality class), material and heat treatment, quantities for the first build and per year, timing, and any country-of-origin requirement.
Send your gear data
Share the drawing or gear data, material, quantities, timing and any country-of-origin requirement. Partial information is fine.
Start a project