Ngoc Nguyen

Even though I already have this many things to work on I procrastinated and whipped up TWO new Mini 42xxx and this.

I love the Bronco!

Sorry for the late reply, thanks a lot! Thanks for the compliment! Thanks for the support!

Hi everyone, this is a rover review from RacingBrick

Another nice thing about the steering shift that I forgot to mention is that it locks itself. You can't switch mode if the HOG is turning or the wheels are steering. The reason is very simple. Since the HOG shaft (which controls the grey knob gear) and the rear steer shaft (which controls the yellow knob gear) are always parallel, once you turn then when the steering shift is in the back position, the arm/tooth of the knob gears will slightly overlap, and the yellow gear will block the steering shift from moving completely into the front position and subsequently meshing with the yellow knob.

There is virtually no backlash at all. The steering is very responsive. You can see it in action here at 0.37: Thanks a lot!

So, how does the steering work? The steering shaft and mechanism are tied into the structure of the undercarriage, so let's take a look through the whole structure. Since I want the model to have 4x4 drive and 4 wheel steering, this is the most compact legal setup. I'm aware of more compact builds but they are not legal or structurally sound enough. The reason the 28z differential is used is that the drive shaft is transmitted directly up from the driving bevel gear to the fake engine right above the rear wheel. There are 3 possible places to put the transmission: between the two axles, right in front of the rear axle, right behind the rear axle. Since the space between the two axles are for the two mode steering, and the space behind the rear axle is for the outriggers, the only possible place is right in front of the rear axle. That means the drive transmission has to bypass the steering axle, and the only combination that works is 28z differential meshing with a 12z gear, which meshes directly above with a clutch 20z gear. In the photo above you can also see that on two sides are the drivetrains for outriggers and HOG steering knob. To accommodate space for the sideways movement at the two ends, the steering must use a 9L liftarm instead of a 7L gear rack. This setup also makes aligning the front and rear steering positions easier. The outriggers are connected to each other through a horizontal axle. This setup is adopted from Akassin's model. On the left side the axle has an 8z gear that meshes with the worm gear to ensure the outriggers can be locked. This is the how the drivetrain for outriggers look from above, for both axles. In order for the front and rear outriggers to rotate in the same direction, the meshing gear in the legs must be in the same relative position to the horizontal axle instead of in mirrored positions. That means they both have to be behind the driving 12z half gears, as highlighted in the photo. You can also see the steering drivetrain has 2 CV joints. What are they for? The logic of the steering mode is like this. Since the steering angle of each axle is very small, around 10 degree, there's no need for a front wheel steering only. Also, front wheel steering doesn't just involve the steering, it also requires locking the rear wheel steering, which increases the complexity of the problem. Therefore I only need two modes: counter steering and crab steering. In these two modes, the front wheel always steer. Therefore I made the HOG permanently connected to the front wheel steering, through the 3 8z gears in the front, as highlighted in the photo below. Meanwhile, the steering shaft for the rear axle goes into the middle of the chassis, but is independent from the steering shaft of the front axle. On the axle, there is an 8z gear and a knob gear separated by 1 stud. In the space between the two axles, there's a block called steering shift. It is 6L long and is build at the center of a 11L axle, so that there's an axle of 2.5L on each side. The space between the two axles is 7L wide, and since the steering shift needs to slide back and forth, it has to be 6L long only. The CV joints at both sides serve two purposes. First, since they have frictionless axle holders, they allow the steering shift to move back and forth. Second, since the frictionless axle holders is 1.5L deep, the steering shift can move by 1L in one direction while is still connected to the other direction by 0.5L. This setup allows transmission from HOG to front wheel steering is continuous; in other words the front axle always steer when the HOG is rotated. When the steering shift is in the back position, the HOG shaft goes through 3 gears to reach the rear axle steer shaft, while in the front position, the HOG shaft goes through only 2 gears to reach the rear axle steer shaft, therefore driving the rear axle in the opposite direction. Thanks to the new 45 degree offset knob gear, both the HOG shaft and the rear steer shaft are parallel. The steering shift has a fixed 8z gear so that a worm gear when rotated can push that gear along with the whole steering shift back and forth by 1L. And that's how the two mode steering works. I'm very happy and proud that I can pull this off smoothly, especially in such a space that's not just small but is also restricted by many other factors.

Why cant it

Given that Zetros's rare (if not nonexistent) appearances among trial trucks, I thought that this set's version of Zetros is just imaginary, but I've found a real life Zetros trial truck! This is probably what 42129 is modeled after.

Who wants a Sariel Technic review? @Maaboo the Witch does!

There's 42114 but I'm not doing a mini of that, and it's not 42139 either cuz 42139 is already mini lol.

I already have a WIP for it, and development may resume next year the earliest, since it can be built right on top of a current mini 42xxx in development

Sets in development til the end of a year - Mini 42xxx - Mini 42xxx - B model for 42xxx - 42100 RC PF Conversion - 42131 Gearbox PF Conversion - 42176 RC PF Conversion Sets of interest - Mini 8258 - Mini 9397 - Mini 41999 - Mini 42009 - Mini 42052 - Mini 42055 - Mini 42066 - Mini 42070 - Mini 42078 A - Mini 42100 - Mini 42110 - Mini 42114 - Mini 42126 - Mini 42131 - Technic 10317 (Defender) - Technic 21327 On another note, the new 13x3 frames allow me to quickly whip up a base for the mini 42055.

Can you share the file for 9L curved panel

The instruction for this model has just made its 100th sale! I don't know why this model still generates sales every once in a while even when 42128 has retired and I have stopped promoting it. I have no idea where the traffic comes from. According to Rebrickable's analytics there are occasional visits from Eurobricks, but I already removed the link to this set from my signature, and sometimes there are sales with no referral site. When I first released this set in August 2021 I had no idea that it would sell this well. That's why I set it as a free MOC for more than a year. It was not until September 2022 that I set it to premium, because another user copied the whole design of the cab in their instruction without giving me credits. And what a journey it has been. The only thing left for this model that I wish I had is a video showing the functions, which I can't do because I don't have the equipment or the editing skills. Every once in a while I tried looking up on Youtube to see if someone did a review on this, but there hasn't been any. But nevertheless, this model has been successful enough, and it's been great luck for me.

Thanks a lot!

Can someone check if the reel can rotate freely in this setup? I don't have the reel part so I can't check.

The next installment in the mini replica colletion: mini Airbus H175 Rescue Helicopter. DEVELOPMENT Even though it is based on the original 42145, I don't like the original color scheme, because neon yellow is a dreadful color in real life, and white ages horribly. Thanks to the release of the 42154, I can build this color scheme instead. The original 42145 has a body of 11M width, and I want the mini model to be motorized as well, so I made the mini fuselage 9M wide. That means it wraps around the battery box completely. and that is the root of the main challenge of the design process. To ensure structural integrity, I have to essentially build a skeleton that wraps around the connection points of the battery box. I even have to use the switch axle hole to connect the vertical support. I also added the diagonal support for the tail to prevent it from bending down, a phenomenon that happens to the tail of the original 42145. The placement of the motor is also problematic. It has an effective height of 4 studs, but because of the 0.5 stud bumps on both sides. the axle hole is offset by 0.5 stud. And the only place to put it is right above the battery box. The bright side is that thanks to the 0.5 offset, I was able to get a 8/16 gear ratio right off the motor. There is space for only two motorized functions, so I decided to motorize the rotor blades and the landing gear, while the winch will be manual. Since the blades only spin in 1 direction, and I'm not really a fan of the 2-speed gearbox, I gave made the switch for the blade work only in one direction. On the other hand, I want the switch for the landing gears to be bidirectional, so I put a direction reversal in the middle. The transmission for the rotor blades is as follows. The axle from the switch will go through a 20/12 gear ratio to the tail rotors to make it spin faster, while it goes through a ratio of 12/28 to the small turntable that drives the main blades, so there's a noticeable difference between rotation speed. The landing gear function is achieved through a linear actuator that pushes the linkages of the front wheels. The linkages of the front wheels are connector to those of the rear wheels through a 13L beam running in the middle, above the battery box. Both front and back wheels use past-the-midline lock mechanisms. This is the whole thing in one photo. As you can see, even though this model has a fairly generous body width (unlike the mini Osprey), things squeeze pretty tightly together. Every cubic stud is premium, and no space goes to waste. In terms of appearance, I think the original 42145 just looks odd. It doesnt look like or even looks closely like the real H175. Therefore improving the look is also a goal of the design process, and Im very happy that I can pull it off. FUNCTIONS Most functions and details of the original model are replicated: - Motorized landing gears - Motorized rotor blades - Manual side winch - Diagonal front doors - Sliding side doors - Side rescue light - Pitot tubes Demonstration: FREE INSTRUCTION: https://rebrickable.com/mocs/MOC-192494/nguyengiangoc/mini-42145-airbus-h175-rescue-helicopter

I like this Unimog more than the other Unimog. You nailed the bold lines of the front grill perfectly.

The real compactness challenge is when the rear wheels are folded up. The transmission for the tilting nacelle, which drives the worm gear, has to be routed to the back. But at the same time, there's a 20z gear on top and the landing gear mechanism in the bottom. The linkage for the wheel needs a midline block to prevent the wheels from collapsing on itself, hence the existence of the 2L axle hole-pin hole liftarm. The pin hole has a 1/2 pin that serves as a block, so when it is fully retracted, in theory the 1/2 pin will collide with the CV joint. But thanks to the magic of flex, in real life, the CV joints and the universal joints are slightly bent to the right while still capable of rotating smoothly, and since the CV joint has a frictionless axle holder it has a small sideway wiggle room.

This is a cross section of the model to show you the inner working. As you can see, there is barely any unused space. Everything about this model is difficult, and I'm very very happy that it is finally functional. The root of the challenges in the design process is the width of the fuselage. The original 42113 has a fuselage that is 9 studs wide and 9 studs tall. I decided to shrink by 2/3, so that the mini fuselage has a height of 6 studs, but the width has to be an odd number, so it can only be 5 studs. Since the walls already take up 2 studs, the space I have for all the gears and functions have to be squeezed in a space of 3 studs width. The landing gear function uses different gear ratios for the front and for the rear wheels, because when folded, the rear wheels only need to move by 90 degrees, while the front wheel, due to being placed further front, needs to move by a larger degree. The front 20z gear also presents a convenient chance for me to use a worm gear to ensure the positions are locked. The rubber piece is used because the swing arm (4L thin liftarm) together with the block is actually longer than 4 studs, which means it will collide with the front column when it rotates up. Fortunately, the rubber piece can bend backward slightly so that the thin liftarm can do a full swing smoothly. The opposite movements of the two pieces of the rear ramp are achieved through simple linkages. When the knob is turned clockwise, the 2x3 quarter liftarm will push the bottom piece down. The highlight of the design is the arrangement of the rotor and the tilt function. Both of them have to go to the wings at an angle, but the wing only can only accommodate one axle in the middle, so that axle will be for the rotor. The tilting is achieved through a meshing of 8z-28z gears at the turntable at the end of the wings. Because the width is only 3 studs and the axle has to be attached to two universal joints on two ends, there is no space for perpendicular transmission. That's why the transmission for the rotors go by a combo of 4 horizontal spur gears. It's very fortunate that the 16z gears fit perfectly under the slot in the middle of a 3x7 panel, so I can cover the middle part with that panel. The tilting transmission has a worm gear driving a 12z gear. Originally I used a worm gear with a 8z gear, but that doesn't generate enough force, and 12z gear is the only bigger gear that fits into that place. To mesh a worm gear with 1 12z gear, the worm gear was put at a 0.5 offset, which means it needs universal joints to be taken back to grid. In the back the transmission has to be geared down twice further. The final gear ratio from handle to nacell is (12/20) x (12/20) x (1/12) x (8/28) = 0.0085 which is 0.8% reduction. That means the tilting nacelle works very slowly, but it is only through such heavy gearing down that the knob can provide enough force to tilt the nacelle. Anything larger will cause the gears to skip.

Words or photos or my phone can't really show how cool this thing looks in real life. I have it on my work desk and it's a real head turner.

I finally got the pieces and did a demonstration video! Everything works flawlessly!!! Development story is coming later.

Did grohl just speak Yoda