JBrost

I take a fishing tackle box full of LEGO pieces for spares/changes/improvements. I don't need them often, but I hate the thought of not having them just in case. Those pieces are sometimes used as spacers for uneven tables too. I also take a large assortment of parts for "infrastructure", i.e. things to make a functional GBC. That includes extension cords & power strips, 9v LEGO train controllers & power adapters, PF to 9v adapters, NXT wires/battery packs/power adapters, PF switches, GBC balls, etc. I also usually try to pack at least a few snacks & drinks as well. Many of the GBC organizers I display with have terrycloth tablecloths and pieces they use for fencing to keep loose balls from falling off the tables & rolling everywhere. I don't have any myself, but it is something I'm considering adding to my collection. And if you're displaying on a concrete floor, some anti-fatigue mats to stand on are awesome. At the larger shows there may be someone who has all the necessary wires & adapters and would rather you use their stuff. But I always take my stuff just in case. Of course I drive to all the events I go to, so I rarely have to worry about an extra box or two or the extra weight involved.

Unfortunately, I don't think anybody is going to be able to give you a solid "will work" or "won't work" answer based just off of the weight. There are way too many other variables that have to be considered. They may work in certain catapult modules while they wouldn't in others. I think it would mostly boil down to how big of a catch area where the balls are landing is build into the module & how accurate/precise the module is in launching the balls. The bigger the catch area where the balls land, the better a module will likely be able to handle non-standard balls. Also keep in mind that non-standard balls are going to behave differently in more than just catapult modules. There are all kinds of modules where a lighter-than-normal ball could perform differently. If you're looking to make some balls to test modules for inclusion in a larger GBC display at a fan event, I would still suggest you get a couple official balls to test with. But if you're just looking for a cheaper alternative you can use when making your own modules for your own enjoyment, by all means, use the 3d printed ones & build the modules so they work with them.

Glad I could help. Happy Building!

The dashed lines indicate that you are trying to wire incompatible variable types. I'm not where I can confirm at the moment, but I believe in your case you are trying to wire two number values into a block that is expecting logic (yes/no) values. I think the default wire output for the light sensor block is the actual light value being read and the default for the ultrasonic block is the distance (in inches or mm) read. To do what you want, you should be able to click on the sensor blocks and get them to expand the wire port options. Try clicking right at the bottom of the square part of the sensor block, just above where you clicked to start your data wire. Done correctly the block will expand downward with a whole bunch more options for things you can wire in & out of the sensor blocks. On each one there should be a logic output wire that you can wire into your logic block. You will also have to set the trigger value of each to determine when the sensor is "triggered" causing it to output a true vs false value. You will be able to do this via the configuration panel at the bottom of the NXT-G screen or via wiring in a variable to the sensor block.

I based my GBC train & stations on Steve Hassenplug's original setup (http://www.teamhassenplug.org/GBC/Train/) that was made back in the RCX days. I use NXTs for mine. One for the loading station & one for the unloading station. I use 9v train track & a 9v train motor rather than the plastic track & PF motors so I don't have to fight with IR control of the train. Each station controls 1/2 of the train track just like it is a motor (using a NXT to 9v converter cable and a 9v to train cable). Two small pieces of electrical tape separate the two sections of track. This allows me to run the two stations independently so the NXTs don't have to communicate with one another& there is no need for wires between the two stations. The train car has a small bump on the side of it that contacts a touch sensor at each station so the train stops at the correct position. It works pretty well if I do say so myself. Over the course of a day as batteries wear down and the train motor heats up I usually have to adjust the power level for the train motor so it stops at the exact position necessary for the unloading station. But I just made the power level configurable in-program from the NXT using the NXT buttons so I can easily adjust it on the fly.

I recall one of the Beyond the Brick GBC walk-through videos having something to that effect in it. Making it worse, it was MY module that the comment was made about-- a module that I cannot recall every having a chain snap(and it has now been to several shows)! Like almost every other LEGO piece, it is all about using it in the right manner and accounting for potential problems. In the case of chain links, they CAN separate relatively easy if they are used in a manner that stresses the links. If that hasn't been taken into account in the design of the GBC module, reliabilty of the module can suffer because of it. In the case of my module, the chain links don't separate because the drive train has a clutch gear in it before the chain. So when a jamb occurred causing the chain to stop, the clutch gear became the "weak link" rather than the chain snapping (pun intended). It's not that you can't use certain parts because they're "not good for GBC", it's just that you have to account for any potential weaknesses in the design of the piece. If a ball can get somewhere and jamb the drivetrain of a module you can either 1) make sure that the drivetrain won't break when the jamb occurs and can be quickly & easily fixed and returned to duty, or 2) re-design the module so that balls can no longer jamb it in the first place. I tend to start with method 1 and work toward method 2 because method 2 requires LOTS of testing. This way I can use a new module in a GBC display with relatively high reliability (module doesn't destroy itself--simply stop module, pick out stuck ball, restart module) while looking for ways to re-design the module to prevent jambs in the first place.

Very nice! I've thought the Xerion would be a nice LEGO build, but never found the time to do it myself. What tires are those? I've been building agricultural tractors and other equipment for a while now and am not completely satisfied with the power puller/off-roader wheels & tires, they just don't have the right size and shape. The ones you're using seem much more realistic. The wheels look like power puller/off-roader wheels. The tires are definitely not LEGO, but they look like they work well. Do you have any problems with them staying in place on the wheels? John

Tom is not a member here on Eurobricks. I do have his contact info, but honestly I don't feel comfortable sharing it here. If you want to send a message to me at john<dot>brost<at>gmail<dot>com, I'll be happy to pass his e-mail to you. I know he'll be happy to answer any questions you might have. I know he's trying to do something special for the 2015 GBC at Brickworld since it is the 10th anniversary of the GBC. In addition, I encourage you to take a look at the Brickworld sub-forum under Events here on Eurobricks. There is usually some good information there. Also be sure to go ahead and register on the Brickworld website (www.brickworld.us) for the convention. Doing so before March allows you some cool benefits. Brickworld doesn't allow registration on-site, so be sure to pre-register. I look forward to meeting you at Brickworld! John