# Solarbotics GM12a 100:1 Mini Metal Gear Motor

**Type:** Product page · **SKU:** POLOLU-638 · **Brand:** [Pololu](https://core-electronics.com.au/brands/pololu-australia)
**Page:** https://core-electronics.com.au/solarbotics-gm12a-100-1-mini-metal-gear-motor.html ([markdown](https://core-electronics.com.au/solarbotics-gm12a-100-1-mini-metal-gear-motor.html.md))

## Retired product

This product is retired and no longer available for purchase. Search the catalogue for an alternative.

## Description

**Discontinuation notice:** Pololu will be discontinuing these gearmotors when the remaining stock is gone. Please consider Pololu's **[micro metal gearmotors](https://core-electronics.com.au/#)** for a wide selection of alternative gearmotors with the same form factor (but longer output shafts).

These miniature brushed DC metal gear motors have 3 mm diameter output shafts that mate fairly well with any 1/8-inch hole output device, including the [Solarbotics RW2 high-traction rubber wheels](https://core-electronics.com.au/solarbotics-rw2-wheel-external-set-screw.html). Alternatively, you can use the [Pololu universal mounting hub](https://core-electronics.com.au/pololu-universal-aluminum-mounting-hub-for-3mm-shaft-2-56-holes-2-pack.html) to mount custom wheels and mechanism to the micro metal gearmotor’s output shaft.

The brass faceplates have two mounting holes threaded for 1.7 (dia) x 0.35 (mm/thd) x 4mm long screws (M1.7 × 4 mm), or you can use Pololu's [mounting bracket](https://core-electronics.com.au/pololu-micro-metal-gearmotor-bracket-pair-black.html), which is specifically designed to securely mount the gearmotor while enclosing the exposed gears.

These small motors come in a variety of gear ratios, have a compact size (1.14" x 0.39" x 0.47"), and weigh only 0.29 oz, making them a great choice for small robot designs — and controlling these low-current motors is a snap with Pololu's [qik 2s9v1 dual serial motor controller](https://core-electronics.com.au/pololu-qik-2s9v1-dual-serial-motor-controller.html).

| ![](https://core-electronics.com.au/media/remote_images/0J3698.600_vPUFH7.png%3F0e327416f268eab2946790646ebc8033) |
|---|
| Solarbotics mini metal gearmotor dimensions (in mm). |

You can download a pdf version of this drawing with imperial dimensions (119k pdf) or metric dimensions (118k pdf).

### Specs for the Solarbotics mini metal gearmotors running at 6 V:

 | gear motor | gear ratio | free-run RPM | free-run current | stall current | stall torque | price |
|---|---|---|---|---|---|---|
| [GM18](https://core-electronics.com.au/solarbotics-gm18-30-1-mini-metal-gear-motor.html) | 30:1 | 566 | 48 mA | 500 mA | 7.29 oz-in | $19.75 |
| [GM12a](https://core-electronics.com.au/solarbotics-gm12a-100-1-mini-metal-gear-motor.html) | 100:1 | 170 | 48 mA | 390 mA | 10.70 oz-in | $19.75 |
| [GM13a](https://core-electronics.com.au/solarbotics-gm13a-150-1-mini-metal-gear-motor.html) | 150:1 | 113 | 40 mA | 370 mA | 14.97 oz-in | $19.75 |
| [GM14a](https://core-electronics.com.au/solarbotics-gm14a-298-1-mini-metal-gear-motor.html) | 298:1 | 71 | 50 mA | 533 mA | 30.70 oz-in | $19.75 |

### Specs for the similar, less expensive Pololu metal gearmotors running at 6 V:

 | gearmotor | gear ratio | free-run RPM | free-run current | stall current | stall torque (oz-in / kg-cm) | price |
|---|---|---|---|---|---|---|
| [5:1 Micro](https://core-electronics.com.au/5-1-micro-metal-gearmotor.html) | 5:1 | 2450 | 50 mA | 360 mA | 1 / 0.1 | $15.95 |
| [10:1 Micro](https://core-electronics.com.au/10-1-micro-metal-gearmotor.html) | 10:1 | 1250 | 40 mA | 360 mA | 2 / 0.2 | $15.95 |
| [30:1 Micro](https://core-electronics.com.au/30-1-micro-metal-gearmotor.html) | 30:1 | 440 | 40 mA | 360 mA | 4 / 0.3 | $15.95 |
| [50:1 Micro](https://core-electronics.com.au/50-1-micro-metal-gearmotor.html) | 50:1 | 250 | 40 mA | 360 mA | 6 / 0.4 | $15.95 |
| [100:1 Micro](https://core-electronics.com.au/100-1-micro-metal-gearmotor.html) | 100:1 | 120 | 40 mA | 360 mA | 10 / 0.7 | $15.95 |
| [150:1 Micro](https://core-electronics.com.au/150-1-micro-metal-gearmotor.html) | 150:1 | 85 | 40 mA | 360 mA | 15 / 1.1 | $15.95 |
| [210:1 Micro](https://core-electronics.com.au/210-1-micro-metal-gearmotor.html) | 210:1 | 60 | 40 mA | 360 mA | 19 / 1.3 | $15.95 |
| [250:1 Micro](https://core-electronics.com.au/250-1-micro-metal-gearmotor.html) | 250:1 | 50 | 30 mA | 360 mA | 22 / 1.6 | $15.95 |
| [298:1 Micro](https://core-electronics.com.au/298-1-micro-metal-gearmotor.html) | 298:1 | 45 | 30 mA | 360 mA | 25 / 1.8 | $15.95 |
| [5:1 Micro HP](https://core-electronics.com.au/5-1-micro-metal-gearmotor-hp.html) | 5:1 | 6000 | 120 mA | 1600 mA | 2 / 0.1 | $15.95 |
| [10:1 Micro HP](https://core-electronics.com.au/10-1-micro-metal-gearmotor-hp.html) | 10:1 | 3000 | 120 mA | 1600 mA | 4 / 0.3 | $15.95 |
| [30:1 Micro HP](https://core-electronics.com.au/30-1-micro-metal-gearmotor-hp.html) | 30:1 | 1000 | 120 mA | 1600 mA | 8 / 0.6 | $15.95 |
| [50:1 Micro HP](https://core-electronics.com.au/50-1-micro-metal-gearmotor-hp.html) | 50:1 | 625 | 100 mA | 1600 mA | 15 / 1.0 | $15.95 |
| [100:1 Micro HP](https://core-electronics.com.au/100-1-micro-metal-gearmotor-hp.html) | 100:1 | 315 | 80 mA | 1600 mA | 25 / 1.8 | $15.95 |
| [150:1 Micro HP](https://core-electronics.com.au/150-1-micro-metal-gearmotor-hp.html) | 150:1 | 200 | 70 mA | 1600 mA | 45 / 3.2 | $15.95 |
| [210:1 Micro HP](https://core-electronics.com.au/210-1-micro-metal-gearmotor-hp.html) | 210:1 | 140 | 70 mA | 1600 mA | 65 / 4.7 | $15.95 |
| [250:1 Micro HP](https://core-electronics.com.au/250-1-micro-metal-gearmotor-hp.html) | 250:1 | 120 | 70 mA | 1600 mA | 75 / 5.4 | $15.95 |
| [298:1 Micro HP](https://core-electronics.com.au/298-1-micro-metal-gearmotor-hp.html) | 298:1 | 100 | 70 mA | 1600 mA | 90 / 6.5 | $15.95 |
| [24:1 Mini](https://core-electronics.com.au/catalog/product/view/sku/POLOLU-991) | 24:1 | 410 | 70 mA | 420 mA | 4 / 0.3 | $14.95 |
| [100:1 Mini](https://core-electronics.com.au/catalog/product/view/sku/POLOLU-990) | 100:1 | 140 | 90 mA | 800 mA | 15 / 1.0 | $17.95 |
| [35:1 Mini](https://core-electronics.com.au/35-1-mini-metal-gearmotor.html) | 35:1 | 350 | 70 mA | 1500 mA | 35 / 2.5 | $17.95 |
| [25:1 20Dx44L mm](https://core-electronics.com.au/catalog/product/view/sku/POLOLU-1092) | 25:1 | 500 | 160 mA | 3300 mA | 20 / 1.5 | $19.95 |
| [19:1 37Dx52L mm](https://core-electronics.com.au/19-1-metal-gearmotor-37dx52l-mm.html) | 19:1 | 250 | 170 mA | 2500 mA | 40 / 2.9 | $24.95 |

**Note:** These gearmotors do not come with mounting hardware, instructions, or packaging. The brass faceplate has two mounting holes threaded for 1.7 (dia) x 0.35 (mm/thd) x 4mm long screws (M1.7 × 4 mm), and Pololu's [micro metal gearmotor bracket](https://core-electronics.com.au/pololu-micro-metal-gearmotor-bracket-pair-black.html) (sold separately) gives you even more mounting options.

## Images

- [Product image 1](https://core-electronics.com.au/media/catalog/product/s/o/solarbotics_gm12a_100_1_mini_metal_gear_motor__pololu_638__00.jpg)