Inertia matching.... yep, you just threw me down another rabbit hole. I did some quick math. Accounting for the plate and ballscrew (no pulley, linear slides, or "stiction"), the inertia is about 220,000g*cm^2. The 425oz stepper is 800g*cm^2. With a 4:1 reduction, we're in the neighborhood of 18:1. The reason why I brought up tooth count was just for engagement. For vibration and resonance, I planned on filling the entire machine with glass sand (blasting media) as it's a bit denser than regular sand. Although the machine will be in a stable environment, I didn't want to get into possible thermal differences. After more digging, my conclusion remained. If it didn't work, it's removable and would only be $8 down the drain. As for the pulleys, I did not consider using an non-flanged spur. The 60mm limitation would be the available space between the gantry (x) and above the rear frame support (y) if the ballscrews remained in the same place. I'm trying to move the pulleys outside, but that presents other issues. There isn't enough space between the rails and the ballscrew support. (Ignore the oversized plate.) Without pushing the rear 4040 cross member inwards, this would be the only way I can see this working without redesigning the current frame. I will continue to play with it and see what I can come up with. Keep in mind that this is only for the Y axis. The X axis should be a bit easier. I just want to say that I really do appreciate the feedback from everyone. Once everything is up, running,and proven, I'll be posting everything with the build. EDIT: Would shifting the ballscrew to the side be frowned upon?