Back on bmcuser I created a post for people who were looking for a budget alternative to printing their own follow focus rings. Here’s the tutorial I wrote up. Adding it here. I also have some other 3d printed files for batteries I’ll be releasing here soon. Have to make sure they print correctly before posting.
Step 3: Start a new project and select a template using millimeters. Doesn’t really matter which one.
• Go here first http://scriptasylum.com/rc_speed/gear_calc.html to key in your values.
Use the second box “calculate gear tooth count.
Pitch: Mod 0.8
Diameter = pitch radius (outside diameter of your lens) (see below)
Calculate and you will have your teeth count
Go to “Draw” at the top and select “key involute gear.”
A dialogue box will open.
Measure your lens using a caliper. Pitch radius is the outside diameter of your focus ring. I always add about 3-4mm to the Shaft Radius. For example: If your focus ring has a diameter of 50mm, then your Shaft Radius will be 25mm and your Pitch Radius will be roughly 28-29mm.
Keyway width is 0
Keyway depth is 0
Teeth count: (see above)
Use the Push/Pull tool to give your ring depth. Around 10-15mm. And that’s it. You’re done. Export as STL and send to your printer. Any questions, feel free to ask here or PM.
Your Shaft Radius will need to be just a hair bigger than your lens diameter. So, if your lens diameter is 50mm, then your Shaft Radius needs to be roughly 25.5, 25.75 or 26mm in order for it to snugly fit on the focus ring. You don’t want to make it exactly 50mm because that’s not going to fit Another caveat, the 3d printer you use may be off a bit. Your drawing may be 25.5mm, but it’ll either print 1mm too big or 1mm too small. It’s kind of trial and error, but I don’t reckon it would be too many tries before you nail it.