Hi! So most stepper motors look like this :res_60ca803f0f2ed8bf4d12a682fc70fb51|450x450
I'm not talking about the code and circuit of controlling it, but how do we actually mount something on it? It is a cylindrical metal tip, without any holes through it or anything, so basically, nothing can be atatched to it! Are we supposed to cut holes through the metal, or is there a way to change the metal cylinder in the middle to something that has mounting spots on it?
You have a collar with a grub screw or a compression type fitting . Google about for it .
Or you can file a flat on the shaft. For light loads you can even use a piece of rubber tubing .
@nitrosop
Google the "stepper motor shaft adapter"
Ebay has plenty of dividable mechanical couplings connecting to various diameters of shafts, leaving You with the same question....
Never played with Mecano?
It will carry anywhere between 5-10kg so it has to be a very powerful connection between whatever I attatch to it and its tip
What do you mean by Mecano? If you mean mechanics, yeah it's my first time. I need something that can connect pretty tight to the stepper since it will lift a pretty big weight (5-10kg). At least 5kg
It seems like the motor with round shaft is unsuitable for the task.
See post #2
Tip - some motors has changeable shafts
Moving 5-10 kg directly from the stepper shaft is highly unlikely.
Maybe you should explain your project in more detail, and it’s likely you’ll need a gearbox or a different type of motor / drive mechanism.
There are a number of different shaft couplers on the market. It is important to use something because it is unlikely you can align a shaft and a bearing perfectly.
Take a look at the various couplers I used and attached them to other shafts in this project of mine.
http://www.thebox.myzen.co.uk/Hardware/CNC_Conversion.html
In the unlikely event you can lift that weight , you need bearings at both ends of the shaft to take the load off the stepper bearings - they are not designed for sideways force .
As implied, You ought to look at DC motors with gearbox .
Ho-hum. 10Kg is a force of 100 newtons and with a 3mm radius shaft that's a torque of 3 x 1e-3 x 100 = 0.3 N-m. A type 23 typically has a holding torque of at least 1 N-m. So it sounds like it isn't really that hard unless you need to apply that force at a larger radius and so need more torque. If you are a bit more specific about what you are trying to do then you may get better advice. As for fitting, I generally buy motors with a flat machined and use a grub screw, though in a couple of cases with cheap surplus motors I have been known to use Loctite. 
The goal is to make a DIY Cassie, something just as Agility Robotics made, but with the legs forward, like humans got. I got the scheme mostly ready with the actuators, but I don't know what type of motors they got at the hips...
I got this video as a reference: Cassie: Walk in the park - YouTube
And I can see 2 different motors at each hip, but what type is it (servo/stepper/...)? That can't be a servo. That's why I thought of using steppers, but I don't see a way of connecting something else to the round shaft. I want to learn more robotics and hopefully, this challenge will teach me the lessons I need
Thanks for the help, check the message I just posted for what the goal is
Not to mention that the motors they're using are round, cylindrical, and not cubic like the usual steppers, which is weird. I wonder if they are simple DC motors
Fully possible but You got the idea!
It really sounds like DC motors. Servo usually have a third shape, not cylindrical, not rectangular.
I found out they got brushless motors. I did some research and discovered a way to control them via ESCs (like these, but as far as I saw if we want to rotate them in the opposite direction we have to flip the cables (manually!!!)
Isn't there a way to control if they rotate left/right via the code? How can we do this? Is there a driver that allows for that to happen?
If you have any doubt that a collet with screws will stay in place, you can file one or two flat sides in the shaft, if they are not already there.
BTW: Steppers don't like forces perpendicular to their shaft.. Make something that is supported on both sides and drive that with the stepper.
