I noticed a missing topic since the new website.
The original one was posted by Zach Levi-Rodgers in June.
Since the subject was interesting and might help some of you, here is the original post, found using google cache :
Hope everyone is safe and well! After being asked this several times by various other 1st ACs this past week I decided to make a post on motor slippage and how to prevent it. I will be making a video about this as well which I will post here.
First of all, check out Fabio’s post ‘Motor trick’ which is a fantastic way to prevent your motor Slipping by mounting a 19mm rod and 15mm rod on the camera, mounting the motor to the 15mm rod and having the 19mm rod sitting underneath the motor.
However, we aren’t always able to mount a 19mm rod on the camera because it’s heavy when coupled with a 19mm bridge plate and the operator will bite your head off. So here’s a few solutions I use to prevent motor slippage In different situations.
1 - The Rubber Band. Not the most elegant of solutions but it works if you have 2 x 15mm rods mounted on the camera. You place the rubberband round the motor and under the lens around the opposite 15mm rod which can prevent the motor bouncing off the lens. An upgrade to this is using caravan ties or thinktank whips. Caravan ties are elasticated with black balls you tie onto and much more hard wearing and less visible than a rubberband.
2 - Use Gravity - By top mounting a 15mm rod or using the ratworks cube bar you can mount your motor above the lens and gravity helps keep the motor firmly attached to the lens instead of jumping off and falling backwards.
3 - Use Metal Rods - Carbon Fibre rods maybe nice and light but after they’re used a few times they become ‘slippery’ and if tightened down too hard they can also crack, not good! Aluminium and Steel rods also get a glazed surface after time but it takes longer. Bright tangerine make Titanium rods which are the fantastic, super lightweight and very very strong and resistant to scratching.
4 - Finally, and arguably the first thing you should check is your motor torque. Sometimes you need the Torque in order to do a fast rack focus or because of a very stiff lens but if your lens has a smooth focus ring, consider reducing your motor torque. This will be particularly noticeable when you calibrate your lens, if you have a weaker torque setting the motor won’t bang off the ends stops so hard and slip. Just be aware that if you lower your torque too much the motor may lag when doing a fast rack.
Let me know if anyone has any other suggestions, My default plan is mounting the motor above the lens. "
Sadly, I could not retreive the comments. Someone shared a link to this page : https://thefocuswheel.wordpress.com/2017/06/30/2-motor-position/
Your are now welcome to repost your previous comment or add new reaction on the subject.