Stationary y-Axis motors

[xtonyx]

Instead of mounting the y-axis motors on the gantry ends, why not mount them the the frame? It would save some weight from the moving assembly.

You'd just need to run your belts as a loop, where each end of belt is clamped to the gantry, and your motor is on one end of the y rail and you would have an idler/tensioner at the other end. This idler could be spring loaded to keep constant tension.

But I haven't even put my first one together yet.

[xtonyx]

BJBSquared has done this, now I don't feel so clever.

http://www.shapeoko.com/forum/viewtopic.php?f=11&t=1510

[cvoinescu]

The main reason is that it's cheaper and simpler to have the motors move along an open belt. It also happens to be easier to extend. In CNC milling, where speed is not much of an issue and the gantry is fairly heavy anyway, the weight of two NEMA17 motors doesn't make that much of a difference, so simplicity wins. You have to remember that low cost was one of the goals when Edward created Shapeoko.

[bjbsquared]

BJBSquared has done this, now I don't feel so clever.

I'm sure you are still clever.

The biggest advantage I think is that routing the wires for the Y motors was easy. Direct to the shield.

Weight difference = 2* (motor +motorPlate -carriagePlate)

Cost was more: An extra idler on each side and A LOT more belting.

The design is versatile size wise. Also stock can be slid in the X and Y direction

[xtonyx]

Thanks for the insight, I didn't consider that it might be easier/cheaper the way it was.