And I’m still disappointed in the kit.
For some details on how I added a motor, scroll down. For why I’m disappointed, keep reading. I’m torn between 3 and 2 stars. On the positive side, this might be the best Robotime kit I’ve built in terms of quality of parts and tolerances. Almost all the parts popped out of the backing boards easily and cleanly, and almost all of the assemblies pressed together firmly, but not so tightly I worried about breaking things, and nothing fit so loosely I had to glue it.
On the downside, now that it’s assembled it’s not that much fun to watch or operate. I bought it because I was intrigued by the multiple arm mechanism for lifting the balls. And from a design and operation standpoint that’s actually pretty cool. Unfortunately (a) it didn’t work until I modified it, and (b) it only lifts one ball at a time with a long gap in between balls. For (1) see below. For (2), that makes it pretty boring. There are never more than 3 or 4 balls moving ‘downhill’ at the same time, and there’s only 1 50/50 switch to change ball direction, so only two downhill paths that merge together partway down. Boring. Compared to some of the other runs I’ve built where there’s constant motion of multiple balls taking multiple routes, this isn’t at all fun to watch. You can see the motorized version in action here: https://youtu.be/sq6Lj-sOuPs
Also, the instructions could be better. The drawings are so small it’s often hard to tell exactly where parts should go, or in what direction they should face. Sometimes they show you a larger section to indicate direction, but not always. Robotime provides better instructions on some of their kits, but I guess this is an older kit and they haven’t updated them.
Back to (1), what didn’t work? The lift didn’t raise the ball high enough to roll out and into the rest of the run. There’s so much play in the mechanism it just didn’t work. I double and triple checked to make sure it was assembled right, and it definitely is. (I’ve built 8 or 9 marble runs and several other wooden kits, so I’m not a newbie to this.) To fix it, I basically had to ‘shorten’ one of the arms by drilling a new hole about 1/3 of its length from the original hole. Photo of the modification (PIC A) attached.
Oh, and instead of the 60mm steel shaft the instructions specify, my kit had a 55mm shaft. That’s not long enough to assemble per the instructions.
To motorize the kit, I took a lead from the video Robotime has on Amazon and other places, that clearly shows a motor driving the kit. I ordered an extra gear from Robotime (free, but $5 shipping from China). I had an extra motor that was included in another kit that had two in the box for some reason, and I had a tiny gear that fit the shaft of the motor. I then glued the gear from Robotime to that tiny one, and screwed it into the motor shaft. (Pic 1 and 2). I glued some extra parts to the frame to act as a motor support, and put some 3M double sided foam tape on top to help keep the motor from moving. (Pic 3). And then used a couple of zip ties to make sure it stayed in place. (Pic 4)
Since the motor only spins in one direction (pay attention to which way you connect the wires) I removed the pieces that keep you from spinning it backwards, and connected the motor through an inline switch (Pic 5) to a 6 volt wall wart (power supply) I got from Amazon. It works well, and moves the lift faster than I would using the crank, but the mechanism is still just way too slow at lifting balls. I won’t be ordering the other kit that uses this lift design.
