CAT 573C Feller


LEGO takes up space.  We all know this, and yet we still seem to try to cram as many working functions into a MOC as we can.  Sometimes it works out well.  Sometimes we have to scrap a few functions.  Other times, the functions are so dense you really cannot believe you got it to work.  This is the story of my wheeled feller.

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CAT 573c Feller

I have been thinking about making a feller for about two years now.  It is a project I have never seen done before, with the exception of two tracked fellers (OK, and my other one).  Over this time, I have been planning, acquiring parts, and making plans, and over the last four months I have been building.  Nothing I have made has been so complicated or so dense.  There is no space left.

As I always do, I stared with the dimensions of the vehicle.  The schematics for the CAT 573C were easily available, so I stared with the chassis.  I knew space would be an issues, so the driveline had to be simple and compact.  The Power Functions XL motor would be geared down 3:1 and mounted just behind the rear axle.  A drive shaft would move through the steering pivot to the front axle.  The rear axle would have simple pendular suspension.  The steering would be completed by two linear actuators placed on either side of the pivot with a PF M motor on top.  Simple enough.

From here, things got complicated quickly.  The MOC would have four remaining functions.  The feller saw, the grapple arms, the feller tilt, and the feller lift.  Since trees are rather heavy, fellers are designed with as many of the system mechanics behind the rear axle.  As such, all of the functions I would add would need to be in the rear, as the front would not have any space.  I quickly learned this would not work.

Eventually, I found what would fit.  The IR Receivers would make up the rear bumper, and the battery box would be directly over them, off to the left.  Two PF Ms would be on the right and would drive two mini Linear Actuators.  These would move two pneumatic valves. These pneumatics would move the lift function and the grapple arms function.  An air tank would supply the pressure from a pneumatic pump placed on the driveline.  Another PF M would be placed over the front axle to give the feller head the tilt functions (it should be noted, 7 designs, and five weeks were spent on this feature alone).  The final PF M was in the feller head, and would drive the feller saw.

After packing, repacking, and packing again, all the features we set.  Then all the cabling and hosing were placed.  No easy task, as I was running out of space, and 25 or so hoses, and 10 cables take up a lot of room.  I added some comfort features to the cable, including a (half) chair and a roll cage.  And so Mr. Technic could get in, a little step.  Then a lot of paneling for the rear, including some access doors on the rear, and the model was done.  Here it is in action.

As you can see in the video, the MOC worked well, but some of the functions did not work as clean as I would have liked.  The drive and steering were fine, with an easy drivability.  There was a lot of mass in the back, so sometimes the torque from the drive motor would cause the back to tip.  The saw worked well enough, and for the most part so did the tilt, but the pneumatic lift struggled.  It was a little overloaded because the saw unit was too heavy.  The grapple arm worked well, but for both pneumatic rams were hard to control.  As always with LEGO pneumatics, they too often are off or on.

Until the next MOC, happy building.

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.

Talon Track


Every once and a while I see something so creative I have to build something like it.  I happened with my HH-65.  It happened with my Zil 132.  And to some extent it happened with my Spitfire.  But when I saw the Urban Buggy from Chrismo, I though I have to make something like it.  It was such a fresh and creative design.  It had such great lines, a perfect stance, and a unique driveline setup.  But while imitation and outright plagiarism are the most sincere forms of flattery, I thought something of my own design would be a better contribution to the LEGO community.  I present my Talon Track Car.

You may find the full gallery here, and the instructions here.

I designed this car to be fast and stable, just like a track car.  I started with a drivetrain that would be reliable and effective.  A PF XL for drive, and a PF M for the steering.  I placed the PF M in the front mounted directly on the suspension unit, with a return to center spring in the middle of the mount.  The system is set up differently than in my Rumble Bee, but uses the same return part.  Each suspension arm would have a single shock absorber.  Directly behind the steering motor was the XL for the drive.  It was geared up with a 20z/12z ratio, with the driveshaft connecting directly to the 20z gear that turned the differential.  The rear suspension used an independent setup that was developed a long time ago for my Red Car Bigger (great name, huh).  If it’s not broke, don’t fix it.  The suspension was planted.  I placed the rechargeable battery box and the IR receiver behind the rear axle.

The car was quick, and didn’t have any problems, but faster would have been cool.  The return to center system worked well, especially for the quickness of the car, and the quickness of the steering.  It was easy to control.  The car was robust, and crashed well.  So go ahead and build your own.  Enjoy.

Spitfire Mk IIa


I am not a very ambitious person.  Sure I made it through college and graduate school, and have managed to work well in job for a while now, but for me to do something challenging, takes a lot of convincing.  It doesn’t happen often.  This project was a little bigger than it should have been, and I got in over my head.  This is not the first time this has happened (1, 2).  The project was interesting enough for me to keep moving forward, even after six months.  I present my 1:12 scale Spitfire Mk IIa.  I hope you enjoy the work.

View the full gallery here, and the work in progress gallery here.  Flickr set is here.

Spitfire 3/4

First, the whole reason I did this project was because of the excellent Baby Twin Otter of Cpt. Postma completed two years ago.  If you have not yet seen this creation, take a look at the above link.  When I first saw this model, I went home a made his variable pitch propeller   This was the first step to my Spitfire, though at the time I did not know it.

I chose to do the Mk IIa version Spitfire for a couple of reasons.  First, the model had to have a three blade prop, because I wanted to use Cpt. Postma’s design.  Spitfires stopped using a three blade prop somewhere in the middle of the MkV series.  Second, I wanted to model a eight gun variant, rather than the cannon variant because I think it has a cleaner look, and I love the red and yellow leading edges on the eight gun variants.  Finally, while it would have been great to do a early model Spitfire with the dark tan camouflage  adding both the dark green and dark tan would have been too expensive, and even more ambitious.  I found a number of pictures of a certain MkIIa with all the features I wanted.  I chose a Spitfire flown by Lt. Tomas Vybiral, who was a Czech pilot with the French Air Force.  The plane was Spitfire P8081 when he flew for the British in Squadron No. 312.  It had simple markings for me to recreate, a camouflage pattern I would be able to do (read afford), and I found some good documents to help my modeling.

Next came the internal planning.  The Spitfire would have working ailerons  flaps, rudder, and elevators (with correlating pilot controls), prop, prop pitch, V-12 engine, and retracting landing gear, all within the 1:12 scale.  Once I had the dimensions calculated, I started placing things in a simple “placeholder” model on my floor.  I constructed the engine, the propeller spinner, pedal/joystick assembly and placed them in the placeholder.  Then I made the placeholder 3D.

It took two months to get the rest of the internals all set.  The required moving various parts of the 3D placeholder, and adding additional parts.  The joystick is connected through various liftarms to the rear elevator, and by axles to the ailerons   The pedals connected though a shaft to the rear rudder.  You can see the gears on the rudder.  The flaps have a simple lever in bottom left side of the cockpit.

The rest of the functions are controlled via Power Functions.  The small 8878 battery box is placed behind the cockpit, as is the IR receiver.  A PF M is housed under the V-12 and drives four mini linear actuators for the landing gear.  It is strong and simple, and works well.  It does not have the correct Spitfire landing gear geometry, but if someone can figure out a way to do it at this scale…well, I can’t figure it out.  A second PF M is used to power the propeller   It is placed directly behind the V-12.  Finally, a third PF M is placed behind the V-12, and works through a system of gears to power two mini linear actuators to move the pitch of the prop.  It’s messy inside, but it has everything I wanted.

After the internals, I had no idea how hard the rest of the Spitfire would be.  LEGO, you need to make more parts in Dark Green.  I know how selfish that sounds, but it would have been more helpful.  Thank to some newer sets, like the 10226 Sopwith Camel, and the  21016 Sungnyemun, it made it much more possible, but still limited me in many places.  I spent the next four months acquiring parts, and placing small plates over the rest of the plane.  With some help on the roundels from Dieterr89, it eventually came together.   The bodywork took a long time.  Too long.  And the lack of some parts in Dark Green forced me to make some concessions.  The canopy frame should be all Dark Green, but it was not going to happen with what is available.  The camouflage is not as clean as I would have liked, and there are some abrupt steps where some plate limitations made the transition for one part to another not smooth enough, such as on the rear fuselage.  Also, try as I might, I could not get the leading edge of the wing to be perfect.  The dihedral did not help either, nor did the yellow leading edge.  Also, the gaps between the control surfaces and the fixed part of the wing and stabilizer was more than I would have liked.  But this has happened before.

I am please with how it turned out, but there are some parts that I wish would be better.  I never seem to remember this when I start a project in this scale, but free moving functions just do not operate well as you hope when you keep adding parts.  The control surfaces work, but they could be smoother and lighter.  The powered functions worked flawlessly. I was very please with the way the markings turned out.  They are not as flush with the plane as painting would cause you to believe, but they make the Spitfire clearly identifiable.

My father would always tell me “never say never,” but it may be a long time before I do another large plane.  But I guess I said that back in 2008.

I hope you enjoy.  Thanks for reading.

3 Speed Sequential Transmission with Changeover


A couple of years ago, I was building a MAN LE with the sole intention of creating a new gearbox.  The tried and true changeover with clutch gears is a great system, and works well in a lot of situations, but I had been disappointed with how it functioned in trucks.  Particularly with the neutral.  I could not have my trucks roll backward.  There had to be a better system.  There were four things I wanted to address:

First, each gear-change had to move seamlessly from one gear to the next.  No neutral.

Second, it had to be easily controllable with power functions.

Third, it had to be sequential.  No first to third gear shifts.

Fourth, it had to work.  Every time.  With no slipping.

The first goal was easy to address.  I came up with a simple sequential gear box, that would move between three ratios all spaced one stud apart.  In order to get to gear three, you had to go through gear two.  To make sure the gears would slip into sync every time, I chose the double bevel gears as the change over gears.  You can see in the video how they slide into gears pretty easily.

The second goal was the most difficult.  I have stuggeled with finding a solution that would allow a motor to move from one great to the next without “overshifting.”  To many designs require you to stop the motor so the gears are perfectly meshed.  After looking at a design from ATRX, I had an idea.  I needed to use the pulley wheels to move the gearbox in three steps.  So, how could I get the pulley wheels to stop at three spots around a half a rotation.  The pulley wheels would be connected via a 24z gear to a differential.  Each side would have M motor, with stops for half a rotation.  One motor would move a half a rotation, transmit the rotation through the differential which would turn it into a quarter rotation, moving the pulley wheels a quarter rotation as well.  One motor would shift from gear 1 to gear 2, then the other motor would shift from gear 2 to gear 3.  It was sequential, and it would only allow you to shift to the adjacent gear.

Finally, it worked.  Every time.  No missed shifts.  I have made a couple of modifications to the gearing and structure to make it a little more compact and with better ratios, but if your looking for a new gear box to use for your next MOC, this might be the ticket.

See the full gallery here.

Used in my Freightliner M2, MAN LE, and ZIL 132.

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.

Flat 6


thirdwigg:

Every once and a while I get picked up by another LEGO blog. I am honored when it happens as it show others value my work. However, it seems to happen when I lease expect it, and in creations I find fun, rather than significant.  Thank you none the less.

Thanks to the Lego Car Blog for posting my Dune Buggy and my Zil 132, and The Brothers Brick for Posting my Rumble Bee.  Spreading thirdwigg is deeply appreciated.

Originally posted on The Lego Car Blog:

Technic Dune Buggy

Porsche Powered Dune Buggy

This monster dune buggy was unearthed by the Elves on MOCpages. K Wigboldy has included steering, all round independent suspension and, best of all, a huge six cylinder engine hanging out the back.

View original

Mack Marble 5T


I confess.  I took the bait, and started on the 2012 You Design It, We Build It before the final rules had been confirmed.  I should know better.  After all my schooling, you would think I have a good idea about how to follow directions.  The first direction is, wait for directions.  But, with all LEGO building, I enjoy what I am creating, and so even after the rules and directions have been given, I still want to contribute to the LEGO community.  So, my next MOC is another Trial Truck, built with the intention of being easy to play with, easy to build, and tough enough to handle child play.  All with instructions, so you can build one.

See Instruction Page

I built this model based on what I thought could be improved on set 9398.  While this new set was a great step forward for the LEGO company, I felt there where a couple of changes that should be made to make the model a better off-roader.  Because I was working with the assumption that this would be something LEGO would produce, I gave myself a couple of constraints.  First, the model had to be less than, or equal to, the cost of 9398.  Second, the model had to have improved off-roading skills.  Third, the model had to have easy playablity, so the drivetrain had to be reliable, the battery should be easy removable, and it should be easy to drive.

I started the frame before the axles.  I placed the battery box directly over the driveshaft.  An XL motor was place behind the BB and three 16z gears above the driveshaft.  One 16z gear went up to the fake motor shaft.  The driveshaft would connect front and rear to the two axles through the new ball joints from 8110.

I then built the two axles, starting with the rear.  To keep the speed of the Mack similar to the 9398, I would gear down the XL motor to about 1:4.  The driveshaft came out of the ball joints and connected to the differential.  I chose two 12z/20z gear sets as the final reduction.  This would keep the driveline a little stronger, and help keep various axles from working their way out of the gears, much like the design of the 9398.  The final gearing was 1:3.89.  It’s not a stump puller, but it could still move up most hills.

The front axle was a little more tricky.  Basically, it had a similar setup, with a PF M motor placed on in it to work the steering.  This was by design.  To keep the driveline reliable, and limit the failure of steering, I kept the steering part of the axle, rather then having components placed in the chassis, and then connected via a shaft to the front axle.  The steering is a little quick for my liking, but it works flawlessly.  To understand more about the axles, check out the instructions.

Through a little trial and error, I connected the suspension, and tweaked it so it would function in a way that was robust, and allow for great movement.  I am still not pleased with how it turned out aesthetically  but it functioned without problems, it supported the model well, and allowed for sufficient articulation, so I left it.

I then added a simple body, a basic rear bed, and added some engine components such as exhaust,  intake, and a simple turbocharger behind the fake motor.  When I was done, I noticed the cab looked a little like an old Unimog.  This seems to be a theme with me, as I love the look of the Unimog.  On the other hand, I do not like the look of too many cabover truck designs, as such, many of my trucks have the slight setback cabover design that is very similar to the Unimog.  My T55 is like this, and this is why I have built so many Unimogs.

The model worked well.  the suspension and stability was perfect.  The truck was stable, and did not roll over, all while being able to handle various terrains.  The gearing was sufficient and would be great for a playing child.  It was easy to change out the 12z/20z gears in the portal axles to a 8z/24z setup which made the truck a little more strong.

It would be a great model for many LEGO fans due to cost, reliability  stability, and playability.  So I have posted instructions for people to enjoy the model as well.  I think it would have been a great LEGO set, then the rules were released.

Next time I’ll wait for the rules.  Thanks for reading.

Full gallery is here.

Sd. Kfz. 173 Jagdpanther Late Version


For some of you, this may come as no surprise, but I like to build with more than only Technic.  I find a lot of enjoyment building with Technic, but as a child I had more fun with the bricks.  My resources (and bricklink.com) now allow me to build some of the things I never could at that time.  To this day I still like making tanks, so I present to you a model of the Sd. Kfz. 173 Jagdpanther.  This is still one of my favorite tanks: simple lines, great stance, decent performance, and for my purposes, able to be made in LEGO.

Building instructions may be found here.

While I love building tanks, I don’t build them often.  Posting a tank to the LEGO community online is asking for trouble.  There are a lot of builders like me who like to build tanks, so it is hard to make a tank that doesn’t take some influence from someone else.  While the design is mine, there are a lot of ideas from others that have influenced this design.  Feel free to take a look as some of the ideas in this gallery.  Thanks to the various builders.

I have some more Technic models in the queue, so until then, enjoy this break from normal.

The full gallery may be viewed here.  Thanks for reading.

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