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.

CAT D5K


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.

Red Sedan


When I got out of college, I started getting back into LEGO; the end of my “dark ages.”  I wanted to make a large supercar, just like everyone else.  But after my first attempt, there were a couple of things I wanted to improve, and the first car did not really look right.  OK, so what needed to change?  I needed to stretch the car, and make the stance a little better, add some features, and make it as real as possible.

See full gallery here.

I used the dementions of the 2005 BMW 5 series as my template.  From these demensions I used the F1 Racer wheels and tires to set the scale, then I determined the wheelbase, got the width, and I went to work.  I first made the rear suspension unit, and then the dual cam V-8.  Then I linked the two with a 4 speed transmission, and a long driveshaft and added a simple parking brake.  It took a little work, but I then added the front suspensions.  I have found it best to use technic beams to mount the front suspension. The A-arms are then attached to this structure, with the shock absorbers placed on this structure and braced with liftarms.  I then connected this directly to the front of the V-8, and connected it to the rest of the chassis with a simple frame.  I used the old steering mounts of the old 8865 supercar, and connected them to the steering wheel through an upside down mounted steering rack.  Of note, the car was going to be big and heavy.  I had to find a way to get two hard shock absorbers at each wheel which limited the suspensions options I had.  In addition, I added a front and rear sway bar, which took a little more space, but it worked.

Then the body.  I worked first on the doors, and the front bumper.  I used a dual pivot design for the doors so they would open even though bricks do not work well with pivots.  Then I did the front and rear quarterpanels, and set the rear bumper in such a way that a full size spare tire would fit.  I then worked on the interior.  I designed a simple tilt steering using a worm gear, and a universal joint.  I made sure to use the great front seat design by Pixsrv, added a rear bench seat, funished the trunk and added all the little compartments in the center console and glovebox.

I finished with rest of the body work.  The roof had a sun roof, and the trunk would have a damped shock to hold open the  trunklid, and added small details and some mirrors.  It was big, and it was done.  I was pleased with my first large car.  It still my most popular on Brickshelf.com.

All in all it was a great experience to learn about how to make a large car, and all the challenges that go with that.  Frankly, since this design, most of my cars have been a little smaller, as it makes the suspension and steering work a little bigger.  Lessons learned.

The full gallery may be found here.

Mercedes Benz Axor Refuse


I am a big fan of garbage trucks.  For some reason I find the combination of a smaller truck,with many features all with a complicated compaction device is a great basis for a complicated LEGO Technic model.  Plus, trucks are fun.

The hardest part was going to be the rear compaction device, so that is where I started.  I decided to use a Geesink Norba design as it would give me the largest opening for the trash in the rear because the mechanicals would be on the bottom on and the top of the opening.  13 studs wide is not much space.  In addition, this would allow me to have the rear hopper pivot up to let the trash out when it was full.  I would need to have three functions going though the pivoting hopper.  One at the pivot, and two connecting at the base when the hopper was closed.

The dumpster lift would be driven through a knob gear when the hopper was closed on the bottom.  The compation device would be operated with a gear on the bottom and a mini linear actuator on the top.  This mini linear actuator would also function as the opener for the rear compactor.  All the motors would be housed on the bottom, with one motor placed next to thebattery box.  The extractor would be operated by another mini linear actuator using a scissors mechanism to move the ejector plate.

The chassis was constructed with a PF XL in front of the steering axle.  The motor would power both the drive, and the extractor changed by a changeover.  The steering motor is placed on the right of the truck.  On the left, another PF M motor powers both the dumpster lift and the lower hopper compaction device.  All power came from a 8878 rechargeable battery box, through two PF IR receivers, and powered four motors: One XL for drive and the extraction plate, one M for steering, one M for the dumpster lift and lower compaction, and one M for upper extraction and hopper opening.

The model worked well, particularly steering and the drive.  However the extraction and the hopper opening was a little less reliable.  The hopper was too heavy for a single mini linear actuator, and the compaction device was not stiff enough.  It happened to get caught on some of the internal edges on the inside of the hopper.  The next garbage truck will need to be built a little more sturdy.

The full gallery may be seen here.

JCB 930 Forklift


It was time for me to to make something that was a little smaller with a lot of functions.  I kept driving by a JCB forklift on the way to work, and I thought I could make that.  I wanted manual functions, including a working fork tilt and dual stage lift, working steering and drive, and a yellow bodywork.

I always start with the hardest part of a model.  For this model, that was the fork.  I wanted to use a dual stage lift as to get the forks to a substantial height.  This design would require a chain that would wrap over a moving frame, and connect on one side to the forks, and on the other side to the body.  The moving frame would be moved by a screw, thereby lifting the forks.  I used a number of worm gears on two 12l axles, connected through the bottom to move the moving frame.  This setup allowed for a pivot point, and a lifting mecanism that would function much like the real JCB 930.  The moving frame consisted of two rows of liftarms, and the forks tied everything together between the moving frame and the worm gears.  A chain went up and over the full assembly to work move the forks as the moving frame was lifted.  It works like this.

I then worked on the driveline.  I added a 3 cylinder motor in the rear, driven by the front wheels, working to keep the functions out of the way of the fork mechanism.  I added a steering axle on the rear, and gave it a pendular suspension setup.  This allowed for some stability on uneven ground, while keeping the front wheels planted for the load as it had no suspension.

I then built the body after the JCB 930, and as I did, I added a tilt freature to the fork.  This feature did not work too well, but it gave me the ability to adjust the pitch of the forks, which we a design requirement.  It was not too stable.  After a little work to the body, and a HOG steering link out the top of the cab, the model was done.

The model worked well, particularly the lift feature.  I was a little disappointed with the tilt feature, as it was a little too wobbly. The drivetrain worked well, and the steering allowed for tight corners.  The suspension give good stability, and offered a little bit of off-road prowess.

The full gallery is here.

LMTV Mini Truck Trial


As I start this new blog, I thought it may be helpful to post some of my older models to show what I have done, and give a little history to my designs.  In the midst of getting into Trial Trucks, I decided it was time to make a new smaller truck.  I designed a mini truck, to test my abilities with smaller functions based on the Oshkosh LMTV military truck, and to take my mind off the design that was taking most of my time.

I chose the six wheel truck as it would make the suspension of the truck a little more simple than other designs.  The rear axles would be tied together on each side, with a pivot point in between each wheel; one for each side.  A single axle would connect both sides through the dual pivot points, and would be powered by a worm gear directly from the drive motor.  This set-up did not require any additional suspension components, and this would allow the front axle to use an unsuspended pendular set up.  The PF M drive motor was placed above the rear wheels and drove an axle that would go to both the front and rear axles.

Like the rear, the front axle would use a worm gear directly from the motor to drive the wheels.  From the worm gear, a 8z gear was used to drive two 12z double bevel gears for each wheel.  Both 12z gears would drive two more 12z double bevel gears to which allowed for drive through the steering axis.  A simple link connected the two steering wheels, and used a rack and pinion setup to transmit the steering function.  It worked well, and allowed the steering motor to slip at steering lock.  A PF M steering motor was placed above the front axle in the cabin.

I created a small bed, and cabin for the truck and decided to build the truck in blue.  As I was browsing through my Brickshelf folder, I noticed I had too many red vehicles, so something blue would be good.  I placed the 8878 battery box, and PF receiver between the cab and the bed.  This allowed for proper center of mass, and gave me a fully functioning bed.

The model worked well.  For such a small vehicle, it took a lot to stop the truck, in part because of the worm gears.  The steering worked well, but the turning radius was limited, due to the poor steering lock.  I was a fun model, and it is still one of my more popular projects on Flickr.  See the full brickshelf gallery for a more complete view.