View Full Version : [Question(s)] Noob question: Using AX-12A for Follow Focus

08-20-2013, 03:53 PM
Hi Folks, I am trying to build a follow focus rig with AX-12A. I hope some can help me with a few questions..
1. Is AX-12A a good choice for this ?
2. Is there a servo mountable gear for AX-12 ? I found links for gears for HiTech, but not for this.
3. How to choose a gear for this project.
Thanks in advance for helping a servo newbie.

08-20-2013, 04:06 PM
1. For how big of a camera?

2. I haven't seen one for sale before. Though you could probably have one 3d printed.

3. Without any designs that is a bit hard to answer. With that being said if you had a design already you could answer that. :P

08-20-2013, 04:27 PM
Thanks for the reply. I am trying to drive a 55mm Nikon D80 kit lens. If a servo mounted gear is not an usual approach, how are gears attached to the servo? I am really early in the process, so I don’t very much in the way of design. Sorry.

08-20-2013, 05:39 PM
I haven't seen anyone using gears with dynamixels. Most robots I've seen are direct.

08-20-2013, 05:44 PM
The servo horn has mounting holes so you can attach brackets to it, if you read the manual you'll find the hole spacing.

As Kevin noted though, you'll probably have to get it made yourself.

I suppose the bigger question is why you want to use a gear in the first place. Servos already have an internal gearbox for increasing torque/decreasing speed.

08-20-2013, 09:22 PM
You can get a large-ish gear and drill the holes yourself.

However, if you need more than 300 degrees of rotation, you probably want a higher-resolution 360-degree encoder, such as found on the MX28.

08-21-2013, 11:50 AM
I suppose the bigger question is why you want to use a gear in the first place.
There lies my ignorance about this. I was hoping to strap a Gear Ring belt on the camera lens, attach a matching gear to the servo and drive the lens. Is this even possible with AX12? If not maybe I have to go for the build your own gear route.