So ran into a bit of an issue when we first used the Butler. While pulling the yarn it would frequently slip over the top of the ball and wrap around the post, stopping the rotation of the Butler. You would then have to unwrap it by hand…very frustrating.
At first I thought it was because my center post was not spinning. But after looking at why the yarn stopped rotating (and accessing some of my previous engineering experience) I realized that the angles on the yarn being pulled off the ball were the cause of the yarn getting stuck.
So my solution is to stop the yarn from slipping over the top, or bottom, of the ball by adding a light tension pulling the yarn to the center of the ball circumference. I achieved this by adding a brass “pigtail” that the yarn is fed through. It is set at a height that should work for most all balls.
So far so good, initial retesting has gone very well!
For prototype purposes I added a platform to set the Butler on. This allows me to test both Butler designs without having to re-cut the parts. Once all the testing is done I will integrate it into the base design.