I'm just getting my feet wet in this "build/design" yourself stuff, and I've doodle out a gizmo I want to make. So if I take a piece of 40x40 vslot, do the dimensions and fasteners available let me put a gantry plate on each side of the 40x40 (opposite but parallel) plate, and tie both gantry plates together to move as one? So wheels in both grooves, and something tying both sides together so it moves as one unit. Or would I have to make my own tie rod or somesuch to pull them together. I need (well... want) to hang gizmo's off both sides of a piece of rail, and the large gantry plate gives me enough extra mounting holes to hang the doodads, but it is not clear to me that the fastener parts are available lengthwise. Weight of the gizmo's is relatively balanced. One side will carry about 40% of the load, the other side 60. With that being said, and the moving parts a total of about 4lbs not including the gantry plates and wheels, would going with the linear rail and the delrin wheels be a better choice. The description of the openrail system says "light loads", but I'm not clear on what light is. Are we talking jsut 3d printer heads?
Is this what you're referring to? It's a system used in many of the OpenBuilds CNC machines. Put a 9mm spacer between the wheels and 6mm spacers each side. The additional washer can be added each side but it is generally not necessary. Screw length required is the sum of the parts plus nut thickness. Use 11mm for the wheel thickness. The opposing side with the eccentric spacers works the same way just note you'll need the eccentric spacers going into the plate at both ends of the screw so both wheels can be tightened equally. As far as a 4lb load goes, you should be fine.
The pictures were pulled from the Sketchup file for the LEAD Machine (the Sketchup file can be found under the Files and Drawings tab). A similar detail can be found on both the WorkBee and the Sphinx designs. There's really no need to. That leaves it open in case someone else needs further clarification or has questions.
