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Hello all! I was reading the forum for quite a long now, but it didn't feel quite right to post, without proper introduction. Well, finally, let me present my first MOC here on Eurobricks:
Remotely Controlled Mecalac MTX

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Here is the quick video showing the operation:

More Pictures:

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Description

Statistics:

  • Weight: ~1500 g
  • Part Count: ~1400
  • Dimensions: L x W x H (without boom): 300 x 140 x 220 mm

Remotely Controlled Functions:

  • Driving & Articulated Steering
  • Continuous 360 Slewing
  • Elevation of 1st boom section ( mLA)
  • Elevation of 2nd boom section (LA)
  • Sweep of the 3rd section (mLA)
  • Elevation of the 4th section (mLA)
  • Articulation of a Bucket (mLA)

Power Functions components:

  • 3 x L Motors
  • 1 x Servo Motor
  • 1 x M Motor
  • 3 x IR Receiver
  • 1 x AA Battery Box
  • 1 x 9V Battery Box

The color-coded render showing the drivetrain:

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The functions are distributed by two gearboxes - one located in the chassis with two clutches, and one in the superstructure with three clutches. The chassis gearbox is switched using the M-motor through a worm gear. The same motor controls the deployment of outriggers (Similar idea is used by Pipasseyoyo in his dump truck http://www.brickshelf.com/cgi-bin/gallery.cgi?i=6254101).

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When the outriggers are raised, the two L motors in the chassis provide driving and steering. After the outriggers are deployed, motors drive two clutches in the superstructure gearbox. The third clutch is driven by the L - Motor located in the driver's cabin. The superstructure gearbox is controlled by a Servo. To make it work I have to get rid of most beloved Servo feature - return-to-center. Otherwise, the gearbox will be switched to neutral, each time the controls are released. The solution turned out to be pretty easy:

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One may say, that using the M-Motor for the gearbox would be easier and more compact. But I like the limited degree of rotation provided by the Servo, so I don't need to stop the motor precisely at the right moment. And, to be honest, after I came up with the Servo solution, I liked so much, that I'd decided to implement it besides some shortcomings.

As a result, 8 functions are driven by 3 motors. But the controll requires some practice, since you need to switch the gearboxes often. And as you can see fro the video it is extremely slow. So you can't actually 'play' with it. But it works.

About the development process

(you can skip it, if it is enough reading for you; I haven't found a way to make a cut)

After I had completed my first working MOC - a Unimog truck, I was looking to build something more technically complex, so I can put to a good use all the gears and u-joints I have accumulated in my parts collection. Well I have achieved that. In the course of the project I have ordered the additional u-joints together with a lot of gears four times, and then a little more. The inspiration came from the ingenious brick-sorting excavator by IbrahimFitzGibbon. About the same time I came across Blackbirs's Technicopedia, and was impressed with the old sets, where often several functions will be controlled by a single motor using some crazy switching mechanism. And when while on trip to Germany I saw it. Mecalac 12MTX excavator working on a narrow street in all its glory. This is it. Compact, complex, with tons of functions packed in a small space. I knew, I must build it. After I scaled the blueprints to the medium wheels I had at the moment (68.7x34R), it was obvious that the implementation at this scale will be almost impossible. Will all the motors and gearbox clutches in place where was almost no space for the structure or drive-lines. So I decided to go for it.

It was extremely hard. You know, when you are completely sick of it, but something keeps you going. Every time I would start working on a new mechanism, the first version will be two or three times bigger than it should. And when after dozens of iterations it will fit, but won't work. So optimization, optimization and optimization. I have 58 LDD files for that thing, but they only reflect major changes, when I needed to start from scratch. In total it took almost three years.

The main challenge was the boom. Mecalac boom have five articulation points instead of three in a traditional excavator. That means that I needed to pass four drive lines through the first rotational axis and three through the second one. Anyone who built the excavator knows how difficult it it is. I wasn't able to use u-joint for the first two axes because of the limited articulation.

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Additional challenge was the implementation of the third articulation point, since the axis of rotation is for that one is rotated at 90 degrees to the previous axis, and they are only few studs apart. Figuring out the way to twist the axes took a loong time.

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At the end I am satisfied with the result. But not more than that. It works. But you can't play with it. Because all the arm functions have a very long drive lines with a lot of gears, I had to heavily  gear it down to be able to overcome all the friction. So the arm functions are extremely slow.  But all the ideas work. I I really love same places in the model. Like the Servo with no-return-to-center clutch, chassis gearbox switch coupled with outriggers deployment, three u-joint passing the chassis' articulation axis at angles. There, I finally used that teeth on the old gearbox gears. Coupled with old style half bushes, it allows driving the axle directly (see the orange drive line below).

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And I hate Yellow color now.

Edited by proran
typos

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So many functions packed into such a small space, I especially like the ingenious method of passing three function through the turntable.  I don't think I seen a build in which so many LA's were used so effectively, and its a very detailed model.  Welcome to Eurobricks!

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Oh wow. That is amazingly complex, nice job. I am honestly a little bit frightened by all of the drive lines crisscrossing the body, but it works, and you made it work. I look forward to seeing more things from you.

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Really amazing work, it is perfect for an introduction, the amount of details and functions is outstanding, and you made an excellent work with the renders and the explanation of all the mechanisms, there are so many clever builds on it and you made a great work making it so compact and powerful, i have subscribed to your channel (the first one and i hope the first of lots of new subscribers) and i hope to see more models by you with this level of awesomeness, and to finish, welcome to Eurobricks and thank you for sharing this amazing model.

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Welcome to EB!

 

 

Honestly, this is one of my favorite MOCs in a long time.  This is really well done.  So many things to love, but specifically love the worm gears at angles. 

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That's mind-blowing! I'm a little sorry that the model is not really playable but it would be a joy to build such an engineering marvel.

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Welcome here, what an introduction!

So beautifully ugly MOC, don't get me wrong, the real thing is ugly so You made a very good work on design :wink:, and all the mechanical solutions, gears, axles, actuators everywhere... pure gearhead porn. :pir-wub:  I also miss a bit the playability, but was just a little compromise for functions, good decision in my opinion.

Special thanks for the very detailed presentation, professional and educational.

 

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Welcome to Eurobricks proran.

This is one brilliant build, so many functions crammed into a model of this size. Amazing.

I look forward to your future builds.

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Thank you for all the kind words!

21 hours ago, JGW3000 said:

I especially like the ingenious method of passing three function through the turntable.

JGW3000,I couldn't stop thinking about your userpic, while looking through the windshield:

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I couldn't turn it the right way, since the polarity will be reserved.

About the passing the functions through the turntable. Here, three functions are passed through the body articulation axis. I believe, this is what you mean.

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Still only two functions are passed through the turntable. I am sure it is impossible to pass three through the traditional turntable while maintaining 360 slewing.  Zblj have come up with ingenious solution in his crane truck, but with the slewing limited to 180 degrees. I believe, you can try it with the new rings from 42055 and using the large turntable to pass the third function.

21 hours ago, Saberwing40k said:

I am honestly a little bit frightened by all of the drive lines crisscrossing the body, but it works, and you made it work.

Yes, I frightened by it too. It doesn't feel right. I promised myself, I will try to avoid such a mess in the next MOC, but now looking at the WIP I have, it seems, I subconsciously like it.

20 hours ago, nerdsforprez said:

So many things to love, but specifically love the worm gears at angles. 

Yes, I like them too. They look nice in the render, but actually turned the structure under turntable into a complete mess. But this is the shortest solution I have found to pass the drivetrain into the turntable. Everything more traditional will make the wheel base two long.

 

17 hours ago, agrof said:

 and all the mechanical solutions, gears, axles, actuators everywhere... pure gearhead porn. :pir-wub: 

What a compliment! Thanks. More of that:

800x533.jpg

Edited by proran
typos

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What a beautiful picture, about that really bizarre (i mean rare but amazing) crossing of the axles with all those u-joints in the articulated body, i really like it, i have seen (and made) a lot of models with nice systems with complex designs that work, but this is one of the most amazing of all, it already looks cool, and it also works, which is even greater, about the turntable with 3 functions passing thru it, it is impossible so far (at least for a 360 slewing, as you said), but i like how you solved this problem and you make a superstructure with its own power inside, is a very clever solution, and that arm is just a truly piece of engineering, lots of functions in that compact arm, i bet this model will inspire many people (including me).

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1 minute ago, Lipko said:

I see some illegal connections there :wink:

Oh, there's a number of them, yes.  I should have mentioned it. The most anti-purist thing is the aluminum foil used to connect old 9v battery to the receiver. I couldn't accept it for quite a while, but at the end I needed to decide between realistic cabin or purist solution. Looking at the final result, I can live with it. 

Other than that there is parts under little stress or rubbing each other here and there, but nothing what really bothers me. 

The thing doesn't stand to the TLG standards, that's for sure. I guess this is next level of building skills. I know some of you here guys do that, but I am not quite there yet.

 

 

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You are more "there" in terms of technical and overall skills than many of us.

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You sir, are a genius and a funny one too! It amazes me how people have no contact with online Lego community and than just post an absolutely amazing project. Like, in their third post... ;)

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This is a beauty of dense design. Too bad the friction is so high that you had to gear down (which introduces even more friction I guess).

At the end you mention that you use the old gear + old bushes to couple the gear directly to the axle. But I am at a loss what you mean with that. Can you elaborate?

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3 minutes ago, Jeroen Ottens said:

This is a beauty of dense design. Too bad the friction is so high that you had to gear down (which introduces even more friction I guess).

At the end you mention that you use the old gear + old bushes to couple the gear directly to the axle. But I am at a loss what you mean with that. Can you elaborate?

The old 16t clutch gear with the toothed surface + the old half bush with teeth.

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7 hours ago, Silvio said:

You sir, are a genius and a funny one too! It amazes me how people have no contact with online Lego community and than just post an absolutely amazing project. Like, in their third post... ;)

No, no, no. Probably, I didn't get the feedback, but I cannot say I have no contact with the community. I learn a lot from Eurobricks, Technicopedia and all other resources. Basically the community was the main reason which keep me building. About the genius thing, it doesn't feel that way. I guess, if you a genius ideas just spark in your head. But in my case it was failure after failure. You can call me patient :) 

I honestly think that building to TLG standards requires more skills and efforts. To come up with the idea is one thing, but make it work reliably under all circumstances and make it fool-proof is a totally different story. Okay, I start going off-topic a bit...

1 hour ago, Lipko said:

The old 16t clutch gear with the toothed surface + the old half bush with teeth.

That's right, thanks Lipko.

teeth.png

The problem here, is that the axle in this case is supported only at one end. So you have no connection between the axle with the clutch and the axle with the clutch gear. Theoretically it should be a problem, but in practice they align perfectly, and I never had a problem with it. Speaking of illegal connections, this is a bad one....:wink:

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25 minutes ago, proran said:

I honestly think that building to TLG standards requires more skills and efforts. To come up with the idea is one thing, but make it work reliably under all circumstances and make it fool-proof is a totally different story. Okay, I start going off-topic a bit...

Sorry for taking it even more off, but I think it's just a matter of discipline and focus. You have to make compromises either way you chose, and the TLG standard is no exception. They make reliable and legal builds but sacrifice complexity, functions (sometimes even important/characteristic functions) and/or authenticity. And don't put them to pedestal, they solutions are anything but fool-proof and reliable-under-any-circumstances. Just take a look at the Porsche. Or the ingenious but very flimsy steering in the Claas.

Edited by Lipko

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