Coffee Table With Sand And Magnetic Ball

If you have acquired the OpenBuilds V-Slot kit or bought part that are similar, use the assembly resources from their website as a good guide for assembling the slide. I bought my parts separately so that I could have a “40×20” V-Slot rail laid horizontally instead of the vertical 20×40 arrangement that the OpenBuilds kit suggests using.

Using a horizontal V-Slot arrangement would allow for a slightly stronger attachment point to the metal pipe rotation axis, but it forces you to design the timing belt system on top of the belt. I will go more in depth to how I designed my custom linear slide, but if you choose to use the V-Slot kit from OpenBuilds, you will have to follow their guide for more information.

After choosing and cutting the length for my “40×20” V-slot, I began mounting the necessary hardware for gantry plate slide:

1. I made mounting locations for the one of the pulleys that support the timing belt by drilling a hole close to on end of the slide, between the two V-Slot channels. I then used an M2.5 brass standoff with a threaded screw extension and a lock nut to secure a mounting location for the pulley that is elevated off the V-Slot. I used Loctite glue for added strength to the connection, since this pulley will have a fixed location on the slide. Then, it’s as simple as mounting the ball bearing pulley with screw on to the standoff (make sure that you don’t tighten it too much).
2. The second pulley will be mounted to the stepper motor on the other side of the slide. I bought a separate flat aluminum bracket that was compliant with my “40×20″ setup for mounting the stepper motor on the slide. I mounted the bracket with 2 drop in T-nuts and mounted the motor to the bracket. I used a 1/16” rubber sheet that I cut to the profile shape of the motor to insulate the vibrations from the motor, making the motor quieter.
3. I bought four separate gantry wheels and a larger gantry plate to be compliant with my “40×20” setup. I mounted the gantry plate in the same way that it’s mounted on the 20×40 V-Slot in the OpenBuilds kit. I made sure to adjust the spacing of the wheels by turning the eccentric spacers on 2 of the wheels until the gantry plate firmly secured and would start gliding when the V-Slot was tilted to one side.
4. The timing belt that I used was a roll of GT2 timing belt (not a loop) that cut to the length that I needed. I mounted 3 more pulleys on to the gantry plate using a different length brass standoff in a V-pattern to maintain the tension in the timing belt. To secure the timing belt to the gantry plate, I used a 1″ right-angled piece of scrap aluminum that I cut to about 50 mm in length. I drilled a hole to the same level as the pulleys and used a timing belt fixing bracket to clamp down the two ends of the cut timing belt. I then used belt torsion springs when necessary to increase the tension of the belt.
5. I mounted the 2 end-stop switches to each ends of the slide by 3D printing a mounting bracket that is compliant with the V-Slot channels. I also 3D printed some bumpers for the gantry plate that extend over the edge of the plate, so that they will contact the switch first.