OCTAN Air Racer

OCTAN is one of my favorite longitudinal themes of LEGO. It gives a little color and identity to many of the racing vehicles that have been produced by LEGO since 1994. I don’t know why it took me so long to start making MOCs with an OCTAN theme, but after last summer’s OCTAN F1, I figured I should do another one.

The full gallery including instructions may be seen here.

OCTAN Air Racer

It was time for me to build another airplane, and I figured a0 small air racer would work well in the OCTAN colors. Right from the beginning, I was sure I wanted to make a biplane, and I wanted a radial engine (all real airplanes have propellers). From there everything was on the table. Off to designing.

I started with the radial. It’s not quite a radial, but rather two perpendicular boxer 4 cylinder engines. Each bank of two cylinders are mounted in a different direction; up, down, port, and starboard, and are connect by one common crankshaft. The side banks are one stud forward, and the up and down banks rear, so all eight connecting rods can fit on a common 5l axle. Two engine crankshafts are mounted at each end. The motor spins well, and quite quickly, but the connection is not exactly “legal,” as the pins on the cylinders are a little stressed.

8 Cylinder Radial

Working backwards, I attached the leading edges of the wings, and the worked on the landing gear. Being an air racer (even a biplane), it had to have retractable landing gear. I connected the two wide spaced legs with a simple axle and bevel joint, and added a worm gear to articulate the action. It is a simply solution, and it functions well.

Air Racer Bottom

Just behind and above the worm gear is the joystick. The roll functions are connected to the bottom wing by gears, and the pitch function is connected by liftarms to the rear elevator. The rudder is fixed. The lower ailerons are connected to the upper ailerons by a simple 9L link. When you move the joystick, all four ailerons move. The cockpit is a little cramped, but when you are racing space is not a concern, only speed.

Air Racer Drive


Air Racer Cockpit

After the radial, the bodywork was the priority for the MOC. I have been slowly acquiring white and green parts over the last year. The airplane was designed as primarily white, with red and green accents. The red stripe worked well, as did the red tail, but I could not find a great way to incorporate the green. I added a little to the tips of the wings, and to the wing control surfaces. I used a couple more stickers that I had left over from set 60025, and the MOC was finished.

I was pleased with how the MOC turned out. The airplane looks strong, and the red and green make the white vibrant. I wish I could have found a better place to incorporate the green. The places it was added seems a little haphazard. The radial turned out great, but I feel a little bad about the illegal build. The landing gear works well, as do the control surfaces. I was pleased with how it turned out. Next up, maybe an OCTAN speedboat. Other ideas?

Happy building.


CAT 586C

My favorite constructions vehicles are feller bunchers. The wheeled ones. So I am naturally inclined to make them. I built a small one; I built a large one. I wanted to build a medium one, but I figured I should get out of the box. At least this time.

The full gallery may be seen here.

CAT 586C

The CAT 586C is a site prep tractor. Forgive me for simplifying the work done by the engineers, but the tractor is basically a 573C with a new implement for site preparation, rather than felling. As always, I stared with scaling the full tractor from CAT’s website, and finding a size that would work well with tires, features, and aesthetics. Then I started building.

CAT 586C Rear

I started with the chassis, to get a sense of the size and the layout. I had a good idea of all the features I would want, and I knew some planning would be required. I then finished the mulcher (implement), which is basically a rotating drum with lots of teeth on it. I used a bunch of 24 tooth gears, and connected them to a rotating driveshaft. The chassis was built with four wheel drive, and was connected to the mulcher driveshaft through a series of gears to increase the speed of the drum.

CAT 586C Underside

Then on to the back of the tractor. Feller bunchers and site prep tractors all have their engines in the back; pretty normal for large tractors with large front implements. But to get the weight as far back as possible, the engine is mounted transversely. This presented a couple of challenges for me. I mounted a I-3 engine on the left in the rear with simple gearbox geared up to connect it to the drivetrain. Just in front of the motor are the two cooling fans, which are also driven by the drivetrain. These are also geared up. For those of you keeping score at home, the drivetrain gears up three separate functions, so rolling the MOC on the floor causes a nice whizzing sound.

CAT 586C Driveline

I added some additional features that mirror the real tractor. First, over the mulcher there is a guide bar that allows the tractor to push trees and shrubs down toward the mulcher. In my MOC this is accomplished by a simple worm gear mechanism. Second, I added a small winch on the rear to get the tractor out of sticky situations. Finally, a small mulching door was installed to allow for more or less entry to the mulcher, again just like the real tractor.

CAT 586C Mulcher

The tractor worked well. Functions were smooth, and required no maintenance during play. The many controls on the front were a little dense, and this caused some finger congestion. The number of rotational features connected to the drivetrain made rolling on the floor a little strained. Thought, this kept the MOC from rolling off the table into a lot of pieces. Everything worked well enough, so maybe it is time to make another feller in this scale. Not today, I still have a lot of other projects to complete first.

Happy Building.


At any given time I have about 4-6 projects going on at a time. This is partly the result of the Queue, which is partly the result of my lack of focus. In the midst of all this planning, I find it therapeutic to sit down, and start something small, simple, and without a plan. Two weeks ago, right after finishing the ATS, I sat down, and in a couple of hours, completed a small windrower.

The full gallery including instructions may be found here.


Some of my favorite MOCs are the smaller non-motorized ones I have done over the years, like my Feller, my Octan F1, my 4×4 8081, and my Sod Harvester. I built the Windrower to fit in this theme. A Windrower, or Swather, is basically a large lawnmower. The blades on the front cut down hay, and pull all the cuttings to the center to make a row of cuttings, or windrow, to be picked up later.

My version is rather simple. The two main wheels are connected to a center differental through two 8z portal axles. The differential drives a small I3 motor in the rear, and a PTO driveshaft comes out the front. The PTO drives a simple harvesting head made of four z24 gears which are connected with a number of z12 gears. The harvesting head can be raised and lowered by a simple worm gear setup. A simple steering system was created for the rear wheels, and it was connected by a liftarm to the smoke stack so you could control the steering.

The body work took a couple of Bricklink.com orders. After recently making a couple of MOCs in red, I felt the Case IH coloring would be a little redundant, so John Deere Green it was. My collection of green is growing, but there were still some parts needed. After everything arrived, I replaced all the red, and added some yellow wheels, and everything was set. A simple MOC, with some fun features, and an infrequent color.

Happy Building.



Kenworth T47

The Kenworth T55 is my favorite Trial Truck I have built. It’s not the best looking, or the most capable, or the most reliable, or even the most popular but it’s the one I keep coming back to. My latest truck is a continuation of the Kenworth series of trial trucks. The T55 would pull a stump, the T47 is quicker, has better steering, and more compliant suspension.


Right from the beginning I knew the truck would have a similar cabin at the T55. It would continue with the four wheel steering, and I added an independent suspension. The dimensions would stay close to the same. From there anything else was fair game. I started with the axles. The new suspensions arms made it a little bit easier to make a good independent design. A CV joint was used at the steering knuckle, which allowed for the steering pivot to be near the wheel. Each wheel had about three studs of travel.

The XL motor was placed on the left of the center line and the rechargeable battery box was placed on the right. A newly acquired Servo Motor was placed rear on the centerline directly in front of the rear axle. I had a little more space left, so I added a simple two speed gearbox. A little more space remained so I added a flat six engine.

T47 Engine

Part of my attraction of the T55 has been it’s coloring, and it’s shape. I wanted to keep the attraction similar, but in a way that would differentiate the trucks. I have been acquiring some green lately, so I thought would be a great color. The cab is basically the same, but now it can tilt so you can work on the engine.

The off road performance was not great on the T55, and the T47 was similar. The independent suspension had too much play at the wheels to be great at steering, and the articulation was not very supple. The truck was great to drive around my house, but when I took it outside it did poorly. The suspension design is better than my last independent set up. There was no slipping of the gears. I think my next design will use the same knuckle, but design a different steering connection. This truck again proves the use of knob wheels rather than a differential for a trial truck. Feel free to make your own, and let me know what improvements you developed.

Happy Building.

MAN TGS Tipper Crane

I like to have a LEGO MOC on my desk at work. I find it to be a good conversation starter for visitors. It also gives my fidgety fingers something to do while I am on the phone. Plus it’s just cool. After I finally removed my 4×4 8081, I figured it would be time to add something new.

The full gallery may be found here. Instructions may be purchased for $5 USD.  Buy Now Button


After a little research, I decided to make a MOC based on a MAN TGS tipper crane truck. I knew the MOC would not have any Power Functions, so I had the space to add a number of features. The truck would have 3 axles, a 4 function knuckleboom crane, three way tipper bed with drop sides, working outriggers, and of course working steering.

I started with the crane. It gave me a little trouble, but after trying countless linkages and connections, I came up with a simple design. I worked from the hook down to the truck. I started with the extending boom which was simply a 13L gear rack, and then added it to the main boom. I used a mini linear actuator (I love these) connecting to a simple linkage to the boom could rotate nearly 180 degrees. While the linkage could be a little more sturdy, it functions well and is controlled from a gear on the back of the crane. Finally, I mounted the second mini linear actuator directly on the turntable to lift the crane. This would be controlled with a gear on the back of the truck.

After the crane, I added the outriggers directly to the turntable. After toying with a lot of complex designs, I settled on something simple. Two 13L gear racks would move to out of the truck, and a pin with stop would be connected at the end and would move to stabilize the truck. I worked with the gearing for the stabilizers and the crane, and managed to get a working system. The center of the truck is pretty dense.

Next was the bed. I developed a simple linkage that would allow another mini linear actuator to tip the bed up. I connected the linkage so the bed could tip three ways. The whole system is three studs tall. At each corner of the bed, I added a simple connector so the bed could tip each way. The direction of tip could be adjusted based on which axles are removed. You can also remove a axle for each side, so contents could be dumped in three directions.

Finally, I worked on the body and the finishing of the truck. I think I got the look of the TGS pretty close, and added features like working doors, an exhaust pipe and an intake. Also, every Technic model in this scale needs to have blue seats, so I added them.

I wish the crane on the truck could support a little more, but other than that, I am pleased with the results. I really liked how the bed turned out. It’s simple and effective. And it all looks quite nice on my desk.

Until my next MOC (or MOD?), happy building.

Instructions can be purchased for $5 USD. Send and email to thirdwigg@gmail.com if you want a set.

Cargomaster Crane

We all have our favorite LEGO sets.  Then we also have sets that we think were pretty cool.  Set 6352 from 1991, the Cargomaster Crane was one of these sets for me.  It was a set simple set, it was perfect for a growing child.  Small, playable, yellow, and it could lift things.

Recently, I decided I wanted to make a little Technic crane.  I researched a number of designs, none of which really struck me as something I wanted to pursue.  I kept coming back to 6352. Why not make a crane like that?  Perfect.  I wanted it to be a nice homage to this classic set.  I was going to make is just like 6352.  Double the size, same shape, complete with container and tractor, and of course a driver.  The full gallery may be found here, and instructions can be found here.

6352 Technic

I stared with a simple frame built for the outriggers at both ends.  I knew I was not going to be able to add a more complex outrigger system at this scale that would reflect the original crane, so I made manual outrigigers just like the original.  I added two steering axles so the crane could drive to and from the site, then I placed a turntable right on top of the chassis.

As I started the superstructure, it become very clear very early, that having an offset crane boom like the original model, was not going to be a good idea.  My model was going to look off, and the balance of the offset boom was going to make stability, both for the superstructure, and the crane as a whole, a problem.  I knew the size of the boom, and decided to place it in the center of the crane.  I then placed the cabin, and set it up for the little technic figure.

The boom was relatively simple; two stage, and 23 studs long.  The outside was simple and straightforward, meant to be sturdy and strong.  The pivot was at the rear on top of the winch, and the elevation ram was connected forward under the front of the boom.  There was a simple worm gear under the front that would drive a set of gear racks, to drive the inner boom.  The inner boom would hold the final boom which was only a series of plates.  Each stage was connect by a two cables to make sure all the booms moved together in unison.  It worked well, even under load, as you can see in the video.

The model worked well, and had perfect balance.  The simple boom extension worked well, as did the winch.  The outriggers gave appropriate stability through all positions.  And it looked very similar to the original model, even with the little tractor.

Mini Skidder

My Mini Feller started after I made this MOC.  I wanted to do a small little project, and I wanted to do something fun and simple, and I thought the Mini Feller would be a great partner to the Mini Skidder.  The skidder is a simple design, that uses simple construction techniques, unlike the Feller.  Also, you can build your own.  Feel free to check out the instructions here.

I started with the rear grabber.  I added a simple worm gear to 8z connection that moved one of the arms, and connected it to the other arm with a 16z to 16z connection.  The axle that connected to the worm gear would exit out of the top of the grabber and allow for movement with your hand.  I attached it to an arm that would attach to the MOC.  The arm would be connected by two arms on each side of different lengths, so the grabber would move in an arc, and connected to the chassis.  On the chassis I connected the rear arm to a 24z gear, and placed a worm gear above it.

I connected the rear part of the skidder to the front part with the new small turntable.  This allowed for simple gear connection with a 20z gear to the Hand-Of-God steering.  This worked well, and kept the model simple.  Just in front of the steering mechanism, I added another 24z gear for the plow.  Taking a cue from set 8069, I set the worm gear vertically, and connected it to the exhaust stack; simple and pretty.  I then filled in the space.  A simple body was added, as was the plow, and wheels, though not in the cleanest of ways.

It was fun little design with simple solutions for the functions.  It’s not as complicated or compromised as my Feller, but still a playable MOC.  Also, its easier to build should you feel the need.

The full gallery may be found here.

Thanks for reading.

Mini Feller

Building with Lego is a continuous formation of compromise.  While my ideal of what my Mini Feller would include was significant, what I could actually accomplish was a compromise of space, function, realism, and frankly the amount of frustration I was willing to tolerate.  So while the final result is a watered down version of what I would have liked, it was the result of me compromising amidst the situation.

Instructions can be found here.

I wanted to make a small model go with my Mini Skidder.  The MOC had to be the same scale, have a decent level of fuctions, and work with my Skidder.  A feller seemed like a good option.  As I looked at what function this MOC would have, I ambitiously stated it must have a working blade, working steering, working grapper, and a working tilt function.  All these functions would be controllable on the back or on top of the cab.

The steering was simple enough.  I added a small turntable at the bottom of the chassis to give the frame some support.  The HOG steering axle would come out at the top of the cab, and join the front and the rear with a small link arm.  Simple enough.  Likewise, I added a differential in the rear part of the chassis, geared up the rotation, sent it though a couple of universal joints to the front of the Feller, connected it through a pair of 12z bevel gears, and attached a saw blade.  Again, simple enough I had steering and a working blade.

It got complicated as I tried to add the arm features.  The lifting of the arm would be done with a 8z gear with a worm gear.  Because there was a driveshaft to the front blade, the 8z gear needed to be placed on the axis of the arm, but out of the way of the driveshaft.  The required a 1 stud offset that also needed to be directed back through the steering axis to the rear of the Feller.  I used a CV joint to allow the axle to slip as the feller would steer.

The tilt feature would require a parallel control that would allow the elevation happen while keeping the feller blade parallel to the ground.  This would require another 8z worm gear connection at the lower rear pivot point of the arms.  I was running out of space.  Of the 7 studs to work with, one was used for the universal joint, one was used for the lifting gear, one for the mounting liftarm, and one for the lifting arm.  I could not add another worm gear system, while being able to actually lift the feller blade.  Additionally, adding a link for the gathering arms would also have to work through this pivot point if I wanted to isolate the movement from the lifting and tilting feature.  I had to give.  A compromise was necessary.  I felt the stability of the feller blade had to be paramount, so I added another support arm.  I also felt gathering arms must remain as they are essential to a feller.  Sorry, but the tilt feature got the ax.  It was the correct decision, but it still tasted a little sour.

It was a great little MOC, and I had a good time creating it.  I hope you enjoy building your own.  The full gallery can be viewed here and the instructions can be viewed here.

Thanks for reading.


Construction equipment was pretty much designed for LEGO Technic.  I learned this while designing my MB Axor Refuse Truck.  Yellow bricks are pretty popular and accessible, the equipment usually has many functions which can be replicated, and working models with power functions can be made to reenact various construction projects for great playablility.  After finally getting some large track links, I figured it was time for me to do a bulldozer.

I wanted to model the CAT D5K for a couple of reasons.  First, it used a two wheel track for each side rather than a three wheel track for each side.  Second, I wanted to do something by CAT.  Third, I decided on the D5K because for dozers of this size I think it looked the best due to its stance and overall balance.  Plus, when I started looking at the scale of the dozer I was to model, I learned the D5K would work best with the parts needed such as the tracks and blade, and work with the internal space allowed.

The base D5K really only has three functions: drive, blade lift, and blade angle.  I had no intention to add a ripper, because, frankly, I ran out of space.  Space became an issue very early.  I had 9 studs to work with between the tracks, and I needed to add four motors, a dummy motor, a battery box, and two receivers, all while retaining the appropriate look.  All the gearing had to be compact, and the linear actuators needed to be placed efficiently.  The real D5K has a manual adjustment for the blade pitch, but all of my designs left something more to be desired, so I took it out.

Both tracks would have their own motor, and I wanted to link them to a dummy engine, which required a differential.  I connected the motors directly to a worm gear which drove a 8z gear.  This gear was on the axle for the rear drive wheel, and connected on the other end to a differential which connected both drive wheels.  This differential functioned as a power take off for the dummy motor in the front of the bulldozer.

Two more motors were placed under the dummy motor.  One connected though a 12z/20z gear reduction for the blade angle.  It proved difficult to supply power for the blade angle function through the blade tilt pivot without taking up too much space.  The second motor was used to adjust the blade height.  After a simple reduction, two mini linear actuators were used to move the blade up and down.  It worked well, and was plenty strong.

I added the battery box under the driver’s seat, and placed the two IR receivers in the top of the cab.  It was not optimal aesthetically, but it seemed to work well for control.  And again, I just ran out of space.  I worked on the body, gave the model a working hood, and built a cabin.

The model worked well, but building with tracks is always a little bit frustrating.  Like it or not, LEGO plastic will never be fully smooth, and this is compounded with the track system.  Also, I found that the dummy motor would lose its connection to the drive wheels, as the axles connecting to the differential would slip out every once and a while.  This seems to be a commom problem with Technic builders, so we will see if the new axles will help.  I liked the size of this model, and it had a good amount of functions.  Now I need to use the tracks for something else.

Maybe another tank.

The full gallery may be found here.

Power Functions 4×4 8081

For most LEGO enthusists, when they purchased the set 8081, they quickly modified the set with a Power Functions drivetrain.  It makes sense.  LEGO models are a little more exciting when they are motorized.  But I guess I went a little backwards.  I wanted to do the fun stuff first, and make the most complicated and compact drivetrain I could make.  I posted the instructions here, and they can also be viewed on Rebrickable.com.

But the comments kept coming from people who wanted to see my model motorized.  So I thought it might be a fun addition.  I added a two PF M motors, a 8878 Battary Box, and an IR receiver.  I tried to keep the modifications simple, so I could easily add the motors to the MOD, and take the system out if I wanted to.  The drive motor was placed on a simple mount that connected to the frame.  The power was fed thought a 8z gear to a 24z gear which then connected directly to the V8 driveshaft.  The driveline was unchanged from the V8 down.  The steering motor was mounted laterally in front of the rear seats.  A 20z double bevel gear drove a 16z gear, then a worm gear moved the final 8z gear which was mounted on the existing HOG steering axle.  I removed the passanger seat which is where I placed the battary box, and created a simple mount for the IR receiver.  The added weight required a new shock absorber, so I added that as well.

The model worked alright.  The drivetrain did well to handle the new power, and I could easily control the Crusier.  The steering motor was a little too powerful for the upside down facing steering rack.  It skipped a little under load, which was a problem over rougher terrain.  The drive motor was a little taxed, so a PF XL would have done a little better.  I guess I could add that, but I am ready to move on to my next model.  Stay tuned.

The full gallery may be found here.


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