View Full Version : [Question(s)] Hex M2 Nut Not fitting into Dynamixel AX-18A Servo

12-25-2018, 02:16 PM
Hello All,

I'm trying to follow the instructions at Step 4 of https://learn.trossenrobotics.com/10-interbotix/crawlers/phantomx-hexapod/172-phantomx-hexapod-metal-assembly-guide.html

Specifically, i'm trying to slide in Hex M2 Nuts into Dynamixel AX-18A Servo but unfortunately the nuts are not fitting in. I can see the inner circle of the nut is not flush with the inner circle of the holes on the servo.

Im afraid of hammering it in, lest i ruin or break the servo. I'm curious about a couple of things and would much appreciate help --
1. How much pressure should I apply to the Hex M2 nut to get it into the servo? Should it involve hammering?
2. The instructions are supposed to be for both the AX-12 and AX-18 servos but the photos show AX-12 servos, do both use the Hex M2 nut?


12-25-2018, 08:31 PM
The AX-12 and AX-18 use the same physical size/enclosure -- the point is that you can interchange them!

The M2 nuts should require firm but not hammering pressure to go in. It should go in with a "corner" inwards, and two "flat" sides parallel to the direction of pushing in.

Note that nuts come in slight variation in size -- there are many standards, and many tolerance grades. If you bought the nuts yourself, you may simply have bought beefier nuts than what Robotis assumes/are using, and thus your nuts won't fit.