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LEGO

Programming is fine and all, but physically making stuff is extremely satisfying. LEGO is one way to achieve that satisfaction. Let's Technic it up =)

2012-12-03 17:55:52

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

It's a 1327 piece kit with three motors, differentials, counter steering, and a generally nice focus on gears. So let's build this thing!

As with all things: toujours, mise-en-place. It takes a few minutes before you start to sort most of the pieces, but it's really not that much work, and it means you're not spending an hour just looking for parts through the build process =D

2012-12-03 19:40:45

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

This is about 1/3rd into the build. We're on diagram 55, which is page 1 of the second (of three) booklets for constructing this model.

2012-12-15 10:25:07

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

A closeup of the differential gears - wikipedia has a nice description of how this thing works.

2012-12-15 10:26:50

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

A full view from the bottom, where most of the interesting things happen.

2012-12-15 10:28:04

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

A side view of the chassis, minus the wheels.

2012-12-15 10:29:15

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

At this point in the build, the kit is actually 100% functional. The motors are remote-controlled (IR), and everything's connected. I changed the placement of the IR sensor; it's supposed to sit upright, connected at the top of the red bricks, but that setup was too flimsy. Instead I lowered it so that it sits at an angle and you can't really wiggle it around, while keeping the IR sensor clear.

Of course, while 100% functional, the model's still a bit sparse, so you get some "trimming" in the kit to make the car look more like a car.

2012-12-15 10:35:03

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

At this point in the build, the kit is actually 100% functional. The motors are remote-controlled (IR), and everything's connected.

However, it's a bit sparse, so you get some "trimming" in the kit to make the car look nice.

First up, wheel "wells" and door wings. I don't like how they're black/orange at the fron but white at the back, so I might buy the while pieces as black pieces at some point.

2012-12-15 10:35:30

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

At this point in the build, the kit is actually 100% functional. The motors are remote-controlled (IR), and everything's connected.

However, it's a bit sparse, so you get some "trimming" in the kit to make the car look nice. After the wheel "wells", we get to build the canopy. Literally, it's not so much a body as just a canopy. This section doesn't really use all that many pieces, and gets hinge-attached to the chassis.

I don't like how the kit is black/orange at the front but white at the back, so I might buy the while pieces as black pieces at some point. I also changed the front section a little, because the base model doesn't have a bonnet. The "engine" wings are fixed, which is really silly. So I changed it so that the bonnet can be lifted, and sits a little off the lights, level with the ground. It's just that little bit nicer.

2012-12-15 11:02:33

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

Here's how I changed the bonnet - it can lift, and has a crossbar for stability underneath, which also acts as a riser.

This just looks much nicer, although the nose can be improved a little with a connector (3m) and a bushel.

Maybe even a tackle block. But that will come later =)

2012-12-15 10:37:24

Let's build a 4x4 Crawler

After the mobile crane, I figured I'd try a slightly more "Technic" oriented model - the LEGO Technic 4x4 Crawler (model 9398).

Dropping the canopy and snapping it onto the chassis with two clicks, and we have a remote controlled 4x4 "offroad" car.

It's pretty cool, the IR works quite well, but there is a downside to this kit: the motors.

The motors that come in the box are the normal power function motors, rather than the XL motors. For smaller models, those motors are fine, but this model weighs around 2kg... I don't know the exact torque that these motors can deliver, but "a low number" is an understatement. They just don't cut it for this model. There's one motor to two wheels, but even with a low range gear assembly (making the model quite slow) there's just no torque. This thing has issues clearing even small obstacles. And the differentials aren't limited slip diffs, so when one wheel comes off the ground, that's it: all the torque goes to the free wheel.

This model can be improved. A lot. When I find a bag of Technics parts for $25 I'll probably add some improvements. And two XL motors with limited slip diffs.

I also don't like how the kit is black/orange at the front but white at the back, so I might buy the while pieces as black pieces at some point. I know you're supposed to put stickers on the pieces, but I'm not 12. This kit's going to live on its own for a while and then the pieces will go into bins for use in other models. Stickers wreck reusability, so the black/white color choice here is pretty bad.

2013-01-20 10:05:13

Let's customize a LEGO Unimog U400

The LEGO Unimog U400 is a massive Technic model with over 2000 pieces. But there are some things that can be improved. For instance, it has no drive or steering motors, the doors are cosmetic (the worst thing in a Technic model. Something pre-shaped that is just bolted in without any need for construction), and the crane arm kind of dangles because it's only supported by the vehicle frame. Let's change those things!

First up, you'll notice the crane arm has its own set of wheels that can be raised or lowered using a worm gear, effectively fixing them in place.

There's also an IR receiver hanging off the back of the cabin for remote controlled drive and steering, and the stationary motor use has been greatly improved.

2013-01-20 10:06:03

Pneumatics

Also, air tanks! Pneumatics without air tanks is a bit sad, really =(

I got two tanks with a pneumatic parts kit I ordered off of eBay, and they fit the side nicely (the white panel is from the 4x4 Crawler, which has the worst colour scheme in a Tecnic model).

2013-01-20 10:06:22

Pneumatics closeup

In order to get air into the tanks without having to run the compressor via the motor, which honestly takes forever and is very noisy, there's a swivel-out nice and big pneumatic hand pump.

2013-01-20 10:08:01

Better electrical control

On the motor side, a bigger on/off switch, and to control motor direction better: a normal two way switch with a gear poke. The battery pack has the switch and the IR receiver attached, with the switch carrying the stationary motor (for running the pneumatic compressor and front tackle (not attached atm) and crane gearing), and the IR receiver carrying the drive motor (XL) and steering motor (servo).

2013-01-20 10:08:15

Have some doors

Oh em gee, the doors are actually doors now! To explain, the newer Technic models come with preshaped pieces; there are two shapes pieces in the picture, for instance. In the original model, the wing (on the right) is just bolted onto the cabin, serving a purely aesthetic purpose, which is pretty much the opposite of why I buy Technic LEGO. So they had to become real doors, instead.

In fact, after adding hinging, they're even more door than most doors are, using full rotation hinging to open up as far as whatever's behind the cabin allows. With the bucket on, that's 180 degrees of door. That's a lot of door, really.

I could probably motorize them with some mini linear actuators (think pneumatic pump, but electrical, and able to both push *and* pull) but not right now. They're also not the most stable atm, since the hinges are relatively far apart, so there's some shear wobbling that can probably be remedied by adding a third hinge at mid-height.

2013-01-20 10:08:30

A better crane

Adding in an XL motor changed the rear axle and chassis height, the crane needed a bit more length for the "outriggers". Also, supporting wheels! This uses a worm gear for lowering/raising the wheel carrier, in the same vein as the Motorised Crane's outriggers. Works reasonably well, and can probably also be motorised. Much like the crane outriggers, which require turning knobs by hand atm. So much left that can be motorized O_O

2013-01-20 10:09:33

Crane pneumatics

Since the crane can now stand on its own due to the tripod configuration of wheels + outriggers, I added some extra pneumatic hose to keep the crane pneumatically connected to the Unimog.

2013-01-20 10:11:04

Motorized drive, engaged

Motorized drive, using an XL motor. Now it's engaged...

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