12.5-EXT Micro Metal Gearmotor (Micro Gear Motor), Extended Rear Shaft, N20 gearmotor

A 3 mm D-shaft, 10 mm long, leaves the 12.5 mm gearbox of the 12.5-EXT micro metal gearmotor (N20 gearmotor, extended rear shaft), whose gearbox is 12 × 10 mm and fixed by two M1.6 holes 9 mm apart. A rear shaft 1 mm across sticks out 5 mm. Here as simplified STEP files.

How these parts are made, and what the levels mean: read the method

• Also searched as: 12.5-EXT gearbox
• Model id: gearmotors-n20-12-5-ext
• Standard: N20 gearmotor · size 12.5

Files

Part key	Simplified
gearmotors-n20-12-5-ext	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
W	Gearbox width		12		12	nominal	L1
H	Gearbox height		10		10	nominal	L1
Lg	Gearbox length		12.5		12.5	nominal	L1
Lm	Motor length		15		15	nominal	L1
OL	Overall length			29.1	29.1	single limit (max), modeled at the limit	L0 (max: one source)
Dm	Motor width		12		12	nominal	L1
E	Shaft length		10		10	nominal	L1
d	Shaft diameter		3		3	nominal	L1
f	Shaft across the flat		2.5		2.5	nominal	L1
B	Front boss diameter		4		4	nominal	L1
h	Front boss height		0.8		0.8	nominal	L1
dt	Mounting hole thread		1.6		1.6	nominal	L1
nh	Number of mounting holes		2		2	nominal	L1
e	Mounting hole offset		4.5		4.5	nominal	L0 (nom: one source)
A	Mounting hole spacing		9		9	nominal	L0 (nom: one source)
Br	Rear boss diameter		5		5	nominal	L0 (nom: one source)
hr	Rear end height		1.2		1.2	nominal	L0 (nom: one source)
dr	Rear shaft diameter		1		1	nominal	L0 (nom: one source)
lr	Rear shaft length		5		5	nominal	L0 (nom: one source)
pt	Terminal spacing		6.9		6.9	nominal	L0 (nom: one source)

Drawing

As a PDF: CC-N20-SZ-12.5.pdf.

What each maker states

• Gearbox length Lg: the makers differ (Pololu 12.5 mm, TT Motor 12.0 mm). The model uses the largest stated, 12.5 mm, so a mount or enclosure made to it clears every maker's motor.
• Front boss height h: the makers differ (Pololu 0.7 mm, TT Motor 0.8 mm). The model uses the largest stated, 0.8 mm, so a mount or enclosure made to it clears every maker's motor.
• This size's can is 15 mm. Motraxx's 15.1 mm can is drawn on its 9 mm box only, so the 12.5 mm box's can is 15 mm, though the motor behind both boxes is the same. Left at the defaults of the open decision (#1372); check your own motor's can if it matters.

The 12.5-EXT micro metal gearmotor beside the 9-EXT

The 12.5-EXT is the last of the 2 N20 gearmotor micro metal gearmotors published here, listed from 9-EXT to 12.5-EXT.

• Gearbox width (W): 12 mm on the 12.5-EXT micro metal gearmotor, the same on the 9-EXT.
• Gearbox height (H): 10 mm on the 12.5-EXT micro metal gearmotor, the same on the 9-EXT.
• Gearbox length (Lg): 12.5 mm on the 12.5-EXT micro metal gearmotor, against 9 mm on the 9-EXT.
• Motor length (Lm): 15 mm on the 12.5-EXT micro metal gearmotor, against 15.1 mm on the 9-EXT.
• Overall length (OL): up to 29.1 mm on the 12.5-EXT micro metal gearmotor, against up to 25.6 mm on the 9-EXT.
• Motor width (Dm): 12 mm on the 12.5-EXT micro metal gearmotor, the same on the 9-EXT.
• Shaft length (E): 10 mm on the 12.5-EXT micro metal gearmotor, the same on the 9-EXT.
• Shaft diameter (d): 3 mm on the 12.5-EXT micro metal gearmotor, the same on the 9-EXT.

The 12.5-EXT micro metal gearmotor in its other versions

• 12.5 Micro Metal Gearmotor (Micro Gear Motor), N20 gearmotor, with the same values.

Other sizes

• One size smaller: 9-EXT Micro Metal Gearmotor (Micro Gear Motor), Extended Rear Shaft, N20 gearmotor, 12 × 10 mm gearbox, 9 mm long, 3 mm D-shaft, M1.6 mounting holes 9 mm apart, Handson Technology, Motraxx, Pololu and TT Motor data.

Documents

• CC-N20-DS-12.5.pdf: 12.5 datasheet: values with levels, sources
• CC-N20-SZ-12.5.pdf: 12.5 drawing: this size's values on the views
• parts.json: the part record of this size (the platform contract)

Sources

pololu-micro-metal-gearmotors, ttmotor-gm12-n20va, ttmotor-gm12-n20va-figures. Full citations: the method page and this size's datasheet.

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