2GodBDGlory

Very cool!

Yeah, I've got a stack of those (2x8, 2x4 and 1x2) that I got years ago at a garage sale. They can be quite useful in anything involving the old 9V system, but nothing like it was ever made for PF, presumably because of the totally different plug design and potential for damage if polarities were reversed.

Thanks! I just took a look, and am pleasantly surprised with how cheap they are! They look very useful, so I'll make a point of picking up some should I be ordering from a seller who has them. Looking at the images on Bricklink, it seems that the rubber continues inside and rubs the ball, adding friction. Is this correct? I had assumed that it was just weird decoration, but maybe not.

Sounds good! I've already thought of a promising alternative, proving once again that constraints catalyze creativity.

Yeah, it's perfectly reasonable to not want lubricant; after all, Lego would never do it! The area I was hoping to use it is in the top of the spoiler on my car. In it, the top section has to slide on transverse axles as the car contracts, but because it is so much higher up than the actuators, it usually binds up. I'm not quite sure how else to build it, but I expect I can think of something, though it may involve compromises.

Working on my [TC21] entry, I found myself needing a small yet tight linear clutch that engaged more smoothly than the official one. Inspiration struck, and I built the one seen below: I haven't seen this design before, though it may have been done, so I thought I'd share it. I reckon this would work and be more compact, but I don't own the socket part, so I can't test it. It could maybe also work as a linear clutch/CV joint combo, I guess.

It does look very nice and light! Do you think removing the rear differential would cause too many problems? As it is, I'd expect that it could get into trouble a lot while off-roading, thanks to the open diff.

It does rather seem like this mold was needed to make this locking function work properly, since there cannot be an axle permanently inside it holding the parts together, because the key has to be able to fit. I'm still not sure where it would be useful in Technic, but at least it's designed for that possibility, rather than making it a blatantly single-use part.

Yeah, I agree. It'll definitely have to be a small set!

Interesting challenge! I kind of want to try in Stud.io. Could you clarify the "rules," though? Does every single part need a unique color, such that a 100-piece set would need 100 different colors, or does just every different mold have to have a unique color, so that all doubles of a given part can be the same color?

At least Lego isn't that fanatical about color coding yet!

Thanks for the thoughtful comment! I'd like to build more colorful stuff, but currently my desire for color is less than my desire to save money... [EDIT] My inspiration won't work after all On another note, I just had a stroke of inspiration for two of the transformation functions: the jet deployment and the roof lowering (not built yet). Both of these need to work immediately when contracting and at the very end when expanding. My idea is to put put these functions going the wrong direction but much faster, so that when expanding, one taps the contraction direction for just a second at the very end of the transformation and when contracting, one taps the expansion direction for a moment right at the start. This ought to prevent binding, if it works as expected. I can't wait to get out of class and work it out practically!

Yeah, that's entirely possible, and while it lacks the precision of a gear it's probably more reliable. There are still gears though, just inside the pullback motors!

Or something square like the 3L axle extender with pinhole (or the axle-based version)? Should I take this to mean Jim had a review copy in hand?

Yeah, that's great! I'll keep it in mind!

I'd expect the pullbacks to have at least one gear for the launch mechanism's ratchet, but your point still stands.

Thanks! I haven't taken any video yet, but I'll think about making one. Yeah, there certainly won't be any interior on this one! Today's build session revealed that I had less space than I was expecting, so stuff will be probably be crammed in desperately. I may have to drop some auxiliary functions, too.

It makes my brain hurt too!

Nice, clean, and simple, with some relatively "big-set" parts in a very little set.

Nice work! I recall seeing concrete pumps at work last summer and thinking it would be cool to see a Technic model of one, what with the huge number of boom joints. I look forward to seeing it finished!

Thanks! I'm glad you like it! You're absolutely right that a different color would make it look way better (Azure, orange, red, or now lime green are all good candidates with the wheel arch available), but of these red is the only color I have any significant number of parts, and even then I'm far from where I'd need to be. I could always order parts, but it'd be a lot, and I'm cheap.

I wouldn't be surprised if there are two pullback motors. The Porsche appears to, at least. As for the focus groups, I expect you're right. The two main audiences for a set like this are kids looking for a play model (where pullbacks are great) and adults looking for a display model (where a lack of real functionality isn't missed, though displaying a model with the wheels steered is nice.) The only audience that really loses out here are those who want their Technic sets to reflect real-world engineering, regardless of the looks or play value, but those seem to be the minority...

Like the Zetros? What would it even show in a set that simple?

Update 6: For this update, I started working to fill in the rear aesthetics and added the deploying "jet engine." The wing is also fairly complicated, because it has to have the top section sliding on the pillars as the width changes, the top had to work as an elevator for the airplane mode, and both pillars had to work as rudders for the airplane. This section was actually designed in Stud.io since I had some time to kill away from my bricks... I still need to hook up these control elements to their inputs, though. I plan on hooking up the rudders to the steering and the elevator to some kind of joystick. Anyways, the jet engine was likely the biggest challenge in this largely aesthetic update. I had originally planned on doing a rear pusher propeller and hooking it up to the drivetrain (variable pitch propellers even existed in my mind!), but I quickly realized that any propeller that could fit simply would be comically small, and more complexity is the last thing I need, so I switched to a simulated jet engine. It was a bit tricky to figure out the right proportions and axis on which to rotate it to allow it to flip between normal rear aesthetics and the engine, but the bigger issue was driving it. It has to rotate very quickly when going from car to airplane mode because any delay will cause the rear deck to contract over it before it can escape. However, when going back to car mode, it has to do its motion at the very end, after the deck has expanded around it. I used two long parallel rubber bands and a bevel gear setup to hook it to the transformation drivetrain, allowing it to slip when its motion is blocked. However, I decided that I didn't want to wear out the rubber bands prematurely, I added a medium-strength linear clutch beforehand, which seems to have an ideal stiffness. However, I will need to add some kind of automatically opening lid over the engine, which may take more torque than it allows. Anyways, I've still got a lot of work to do, but I'm starting to feel like the end may be in sight, if only I can make the transformation reliable. My biggest issue there is that the sliding parts in the rear wing constantly bind up when the contraction is in progress, but we'll see what happens!

Nice! They do already exist from that Mindstorms set, but this should make them quite a bit cheaper!