Hm. Maybe I'm having a really dense day, too much time out in the sun this afternoon. Or else I'm missing something -really- fundamental. Let me wallow in ignorance for a moment. (Somebody will thank me someday. I hope.) Sorry in advance for the verbosity here also. (I'm an ex-project manager, and hence incurable.)
OK, the motor mount (and motor) is bolted on at one end of the "drive-line extrusion", yes? The shaft coupler at the motor end supports that end of the ACME rod. At the extreme other end of the ACME rod is another bearing, presumably supported in a block attached to the far end of the extrusion, and that bearing's really just there to support the far end of the spinning rod. Otherwise the far end of the ACME rod would flail around when the gantry is near the motor's end of the system.
Drive line extrusion is attached to the underside of the table. If we make the motor spin, all we have (so far) is a spinning threaded shaft. No attachment to gantry, and therefore no gantry motion.
Your bearing block, the VXB radial bearing, and bearing block cover are a three-part sandwich that is to be attached to the bottom beam of the gantry, right? The "thread follower" components (Dumpster nut and other associated bits) are on either side of the bearing block "sandwich", and something in that lot engages the ACME threads, and thereby serves to push against the bearing block sandwich. That complete assembly moves the gantry back and forth along the ACME rod when said rod rotates. Right?
My problem (perhaps poorly stated earlier) is that the VXB radial bearing in the center of the gantry bearing block "sandwich" will only slide 6 inches down the ACME rod before it jams onto the rod. At this instant I -only- have the 3-part bearing block sandwich installed: no Dumpster nut, which I thought was the part with threads that engage the ACME rod. (None of the thrust washers etc either.) In this condition, I would expect to be able to slide the gantry along its full travel, with the inner circumference of the VXB bearing sliding gracefully and precisely along the ACME rod. It's going to do that in normal operation anyway, yes?
Maybe if I had all of the driveline parts in hand I'd know what it is that I am overlooking...  |