I'm sorry if this has been addressed before, but the forum is waaaaaayyy too deep to search is such a short time!

Basically, I have a 4 ft. gantry, chain driven by two slaved motors, one on each side. I still have some amount of racking with this setup and it is driving me stupid!

I am familiar with the moving knot cable system, but the structure of my machine makes it a bit difficult to implement, but not impossible. Another thought I had was that I could couple the two sides together with a shaft. My motors are single ended, so I couldn't do it there, but if I added a shaft with a sprocket on each end and rode the chain over them, it would force them to move together. And this would be the easier of the two options to implement.

Are there any draw backs to the shaft option where the knot cable would be better?

Thanks.