Micro Metal 42x19mm wheel Mounting Dimensions


I’ve been looking at the Micro Metal Gearboxes with the extended mounting and 42x19mm wheels.

I can see that the #2 screws are on 18mm centres but how far are these from the end of the motor (say electrical connection end)?

When the 42x19mm wheel is fitted how much further our does the wheel protrude compared to the shaft end?

Thanks for any assistance, it’ll help me model my robot a head of building.

Best regards,


Hello, Colin.

The micro metal gearmotors are listed as 26 mm long and the centers of the mounting holes are 4.25 mm from the closer end of the bracket. The brackets are 17.3 mm long. 26 - 17.3 + 4.25 = 12.95 mm. This means the electrical connections are about 13 mm from the centers of the mounting holes.

- Ryan

Usually, the end of the motor shaft is almost flush with the face of the hub, on only the tire extends past the shaft. Unfortunately we don’t have a mechanical drawing for the tire we use for these wheels. I measured the tire with my caliper and it looks like it extends a little more than 4mm past the hub face.

- Ryan

Cheers Ryan,

I’d been looking at the pictures, the gear box doesn’t appear to go to the end.

I was guessing it was a 0.3mm recess, given the gearbox dimensions, but wanted to confirm. It’s the overall mount position to outer edge of wheel that’s most important to me.

Best regards,

EDIT: Oops, just noted the second post once I send! I’ll allow 5mm for recess and tyre… should be close enough for me :smiley:

You haven’t said why you need to know these dimensions, but, if you are designing a wheel well, I’d be wary of only having less than 1 mm of space around the tire. On the RRC04A chassis, there is about a 4 mm gap on both sides of the tire in the axis parallel to the shaft.

- Ryan

I’m considering a different chassis and drive train for one of my minisumo. I’m playing with CoCreate on models again… the personal edition is FREE!

The outer edge of the wheel is not enclosed but I’ve got a 100mm constraint on the width. I’d usually be working with a couple of mm clearance, with a reasonable dimensions it’s not too hard to design around closer tolerances.

The overall length is in the right sort of ball park (26 motor and gearbox, 9.3 shaft and 4mm tyre overhang). This give a reasonable back to back space and still allow 5mm on width.